Combining Early Ischemic Change and Collateral Extent for Functional Outcomes After Endovascular Therapy: An Analysis From AcT Trial

BACKGROUND

Early ischemic change and collateral extent are colinear with ischemic core volume (ICV). We investigated the relationship between a combined score using the Alberta Stroke Program Early Computed Tomography Score and multiphase computed tomography angiography (mCTA) collateral extent, named mCTA-ACE score, on functional outcomes in endovascular therapy-treated patients.

METHODS

We performed a post hoc analysis of a subset of endovascular therapy-treated patients from the Alteplase Compared to Tenecteplase trial which was conducted between December 2019 and January 2022 at 22 centers across Canada. Ten-point mCTA collateral corresponding to M2 to M6 regions of the Alberta Stroke Program Early Computed Tomography Score grid was evaluated as 0 (poor), 1 (moderate), or 2 (normal) and additively combined with the 10-point Alberta Stroke Program Early Computed Tomography Score to produce a 20-point mCTA-ACE score. We investigated the association of mCTA-ACE score with modified Rankin Scale score ≤2 and return to prestroke level of function at 90 to 120 days using mixed-effects logistic regression. In the subset of patients who underwent baseline computed tomography perfusion imaging, we compared the mCTA-ACE score and ICV for outcome prediction.

RESULTS

Among 1577 intention-to-treat population in the trial, 368 (23%; 179 men; median age, 73 years) were included, with Alberta Stroke Program Early Computed Tomography Score, mCTA collateral, and combination of both (mCTA-ACE score: median [interquartile range], 8 [7-10], 9 [8-10], and 17 [16-19], respectively). The probability of modified Rankin scale score ≤2 and return to prestroke level of function increased for each 1-point increase in mCTA-ACE score (odds ratio, 1.16 [95% CI, 1.06-1.28] and 1.22 [95% CI, 1.06-1.40], respectively). Among 173 patients in whom computed tomography perfusion data was assessable, the mCTA-ACE score was inversely correlated with ICV (ρ=-0.46; P<0.01). The mCTA-ACE score was comparable to ICV to predict a modified Rankin scale score ≤2 and return to prestroke level of function (C statistics 0.71 versus 0.69 and 0.68 versus 0.64, respectively).

CONCLUSIONS

The mCTA-ACE score had a significant positive association with functional outcomes after endovascular therapy and had a similar predictive performance as ICV.

Timing of Spot Sign Appearance, Spot Sign Volume, and Leakage Rate among Phases of Multiphase CTA Predict Intracerebral Hemorrhage Growth

BACKGROUND AND PURPOSE

The presence of spot sign is associated with a high risk of hematoma growth. Our aim was to investigate the timing of the appearance, volume, and leakage rate of the spot sign for predicting hematoma growth in acute intracerebral hemorrhage using multiphase CTA.

MATERIALS AND METHODS

In this single-center retrospective study, multiphase CTA in 3 phases was performed in acute intracerebral hemorrhage (defined as intraparenchymal ± intraventricular hemorrhages). Phases of the spot sign first appearance, spot sign volumes (microliter), and leakage rates among phases (microliter/second) were measured. Associations between baseline clinical and imaging variables including spot sign volume parameters (volume and leakage rate divided by median) and hematoma growth (>6 mL) were investigated using regression models. Receiver operating characteristic analysis was used as appropriate.

RESULTS

Two hundred seventeen patients (131 men; median age, 70 years) were included. The spot sign was detected in 21.7%, 30.0%, and 29.0% in the first, second, and third phases, respectively, with median volumes of 19.7, 31.4, and 34.8 μl in these phases. Hematoma growth was seen in 44 patients (20.3%). By means of modeling, the following variables, namely the spot sign appearing in the first phase, first phase spot sign volume, spot sign appearing in the second or third phase, and spot sign positive and negative leakage rates, were associated with hematoma growth. Among patients with a spot sign, the absolute leakage rate accounting for both positive and negative leakage rates was also associated with hematoma growth (per 1-μl/s increase; OR, 1.26; 95% CI, 1.04-1.52). Other hematoma growth predictors were stroke history, baseline NIHSS score, onset-to-imaging time, and baseline hematoma volume (all P values < .05).

CONCLUSIONS

The timing of the appearance of the spot sign, volume, and leakage rate were all associated with hematoma growth. Development of automated software to generate these spot sign volumetric parameters would be an important next step to maximize the potential of temporal intracerebral hemorrhage imaging such as multiphase CTA for identifying those most at risk of hematoma growth.

Association between CT Perfusion Parameters and Hemorrhagic Transformation after Endovascular Treatment in Acute Ischemic Stroke: Results from the ESCAPE-NA1 Trial

BACKGROUND AND PURPOSE

Hemorrhagic transformation can occur as a complication of endovascular treatment for acute ischemic stroke. This study aimed to determine whether ischemia depth as measured by admission CTP metrics can predict the development of hemorrhagic transformation at 24 hours.

MATERIALS AND METHODS

Patients with baseline CTP and 24-hour follow-up imaging from the ESCAPE-NA1 trial were included. RAPID software was used to generate CTP volume maps for relative CBF, CBV, and time-to-maximum at different thresholds. Hemorrhage on 24-hour imaging was classified according to the Heidelberg system, and volumes were calculated. Univariable and multivariable regression analyses assessed the association between CTP lesion volumes and hemorrhage/hemorrhage subtypes.

RESULTS

Among 408 patients with baseline CTP, 142 (35%) had hemorrhagic transformation at 24-hour follow-up, with 89 (63%) classified as hemorrhagic infarction (HI1/HI2), and 53 (37%), as parenchymal hematoma (PH1/PH2). Patients with HI or PH had larger volumes of low relative CBF and CBV at each threshold compared with those without hemorrhage. After we adjustied for baseline and treatment variables, only increased relative CBF <30% lesion volume was associated with any hemorrhage (adjusted OR, 1.14; 95% CI, 1.02-1.27 per 10 mL), as well as parenchymal hematoma (adjusted OR, 1.23; 95% CI, 1.06-1.43 per 10 mL). No significant associations were observed for hemorrhagic infarction.

CONCLUSIONS

Larger "core" volumes of relative CBF <30% were associated with an increased risk of PH following endovascular treatment. This particular metric, in conjunction with other clinical and imaging variables, may, therefore, help estimate the risk of post-endovascular treatment hemorrhagic complications.

Total intracranial hemorrhage volume measurement summating all compartments best in traumatic and nontraumatic intracranial bleeding

BACKGROUND AND PURPOSE

The ANNEXA-4 trial measured hemostatic efficacy of andexanet alfa in patients with major bleeding taking factor Xa inhibitors. A proportion of this was traumatic and nontraumatic intracranial bleeding. Different measurements were applied in the trial including volumetrics to assess for intracranial bleeding depending on the compartment involved. We aimed to determine the most reliable way to measure intracranial hemorrhage (ICrH) volume by comparing individual brain compartment and total ICrH volume.

METHODS

Thirty patients were randomly selected from the ANNEXA-4 database to assess measurement of ICrH volume by compartment and in total. Total and compartmental hemorrhage volumes were measured by five readers using Quantomo software. Each reader measured baseline hemorrhage volumes twice separated by 1 week. Twenty-eight different ANNEXA-4 subjects were also randomly selected to assess intra-rater reliability of total ICrH volume measurement change at baseline and 12-h follow up, performed by three readers twice to assess hemostatic efficacy categories used in ANNEXA-4.

RESULTS

Compartmental minimal detectable change percentages (MDC%) ranged between 9.72 and 224.13, with the greatest measurement error occurring in patients with a subdural hemorrhage. Total ICrH volume measurements had the lowest MDC%, which ranged between 6.57 and 33.52 depending on the reader.

CONCLUSION

Measurement of total ICrH volumes is more accurate than volume by compartment with less measurement error. Determination of hemostatic efficacy was consistent across readers, and within the same reader, as well as when compared to consensus read. Volumetric analysis of intracranial hemostatic efficacy is feasible and reliable when using total ICrH volumes.

Clot composition and recanalization outcomes in mechanical thrombectomy

BACKGROUND

Mechanical thrombectomy (MT) has become standard for large vessel occlusions, but rates of complete recanalization are suboptimal. Previous reports correlated radiographic signs with clot composition and a better response to specific techniques. Therefore, understanding clot composition may allow improved outcomes.

METHODS

Clinical, imaging, and clot data from patients enrolled in the STRIP Registry from September 2016 to September 2020 were analyzed. Samples were fixed in 10% phosphate-buffered formalin and stained with hematoxylin-eosin and Martius Scarlett Blue. Percent composition, richness, and gross appearance were evaluated. Outcome measures included the rate of first-pass effect (FPE, modified Thrombolysis in Cerebral Infarction 2c/3) and the number of passes.

RESULTS

A total of 1430 patients of mean±SD age 68.4±13.5 years (median (IQR) baseline National Institutes of Health Stroke Scale score 17.2 (10.5-23), IV-tPA use 36%, stent-retrievers (SR) 27%, contact aspiration (CA) 27%, combined SR+CA 43%) were included. The median (IQR) number of passes was 1 (1-2). FPE was achieved in 39.3% of the cases. There was no association between percent histological composition or clot richness and FPE in the overall population. However, the combined technique resulted in lower FPE rates for red blood cell (RBC)-rich (P<0.0001), platelet-rich (P=0.003), and mixed (P<0.0001) clots. Fibrin-rich and platelet-rich clots required a higher number of passes than RBC-rich and mixed clots (median 2 and 1.5 vs 1, respectively; P=0.02). CA showed a trend towards a higher number of passes with fibrin-rich clots (2 vs 1; P=0.12). By gross appearance, mixed/heterogeneous clots had lower FPE rates than red and white clots.

CONCLUSIONS

Despite the lack of correlation between clot histology and FPE, our study adds to the growing evidence supporting the notion that clot composition influences recanalization treatment strategy outcomes.

Risk of stroke within 3, 7, 14, 21 and 30 days after influenza vaccination in Alberta, Canada: A population-based study

BACKGROUND AND PURPOSE

Influenza vaccination is associated with a longer-term protective effect against stroke; however, it has a short-term inflammatory response which may increase short-term risk of stroke. The aim was to investigate the association between influenza vaccination and short-term risk of stroke in adults.

METHODS

Administrative data were obtained from the Alberta Health Care Insurance Plan for all adults in Alberta, Canada, from September 2009 to December 2018. The hazard of any stroke (acute ischaemic stroke, intracerebral haemorrhage, subarachnoid haemorrhage and transient ischaemic attack) within 3, 7, 14, 21 and 30 days of influenza vaccination compared to unexposed time was analysed using Andersen-Gill Cox models, with adjustment for age, sex, anticoagulant use, atrial fibrillation, chronic obstructive pulmonary disease, diabetes, hypertension, income quintile, and rural or urban home location.

RESULTS

In the entire cohort consisting of 4,141,209 adults (29,687,899 person-years), 1,769,565 (42.7%) individuals received at least one vaccination. In total 38,126 stroke events were recorded with 1309 occurring within 30 days of a vaccination event. Influenza vaccination was associated with a significantly reduced hazard of stroke within 3 days (hazard ratio [HR] 0.83, 95% confidence interval [CI] 0.73-0.93), 7 days (HR 0.87, 95% CI 0.80-0.95), 14 days (HR 0.87, 95% CI 0.81-0.93), 21 days (HR 0.85, 95% CI 0.80-0.91) and 30 days (HR 0.66, 95% CI 0.65-0.68).

CONCLUSIONS

An increased early risk associated with vaccination was not observed. The risk of stroke was reduced at all time points within 30 days after influenza vaccination.

What Is a Meaningful Difference When Using Infarct Volume as the Primary Outcome?: Results From the HERMES Database

BACKGROUND

Ischemic stroke lesion volume at follow-up is an important surrogate outcome for acute stroke trials. We aimed to assess which differences in 48-hour lesion volume translate into meaningful clinical differences.

METHODS

We used pooled data from 7 trials investigating the efficacy of endovascular treatment for anterior circulation large vessel occlusion in acute ischemic stroke. We assessed 48-hour lesion volume follow-up computed tomography or magnetic resonance imaging. The primary outcome was a good functional outcome, defined as modified Rankin Scale (mRS) scores of 0 to 2. We performed multivariable logistic regression to predict the probability of achieving mRS scores of 0 to 2 and determined the differences in 48-hour lesion volume that correspond to a change of 1%, 5%, and 10% in the adjusted probability of achieving mRS scores of 0 to 2.

RESULTS

In total, 1665/1766 (94.2%) patients (median age, 68 [interquartile range, 57-76] years, 781 [46.9%] female) had information on follow-up ischemic lesion volume. Computed tomography was used for follow-up imaging in 83% of patients. The median 48-hour lesion volume was 41 (interquartile range, 14-120) mL. We observed a linear relationship between 48-hour lesion volume and mRS scores of 0 to 2 for adjusted probabilities between 65% and 20%/volumes <80 mL, although the curve sloped off for lower mRS scores of 0-2 probabilities/higher volumes. The median differences in 48-hour lesion volume associated with a 1%, 5%, and 10% increase in the probability of mRS scores of 0 to 2 for volumes <80 mL were 2 (interquartile range, 2-3), 10 (9-11), and 20 (18-23) mL, respectively. We found comparable associations when assessing computed tomography and magnetic resonance imaging separately.

CONCLUSIONS

A difference of 2, 10, and 20 mL in 48-hour lesion volume, respectively, is associated with a 1%, 5%, and 10% absolute increase in the probability of achieving good functional outcome. These results can inform the design of future stroke trials that use 48-hour lesion volume as the primary outcome.

Quality of Life After Intravenous Thrombolysis for Acute Ischemic Stroke: Results From the AcT Randomized Controlled Trial

BACKGROUND

Recent evidence from thrombolysis trials indicates the noninferiority of intravenous tenecteplase to intravenous alteplase with respect to good functional outcomes in patients with acute stroke. We examined whether the health-related quality of life (HRQOL) of patients with acute stroke differs by the type of thrombolysis treatment received. In addition, we examined the association between the modified Rankin Scale score 0 to 1 and HRQOL and patient-reported return to prebaseline stroke functioning at 90 days.

METHODS

Data were from all patients included in the AcT trial (Alteplase Compared to Tenecteplase), a pragmatic, registry-linked randomized trial comparing tenecteplase with alteplase. HRQOL at 90-day post-randomization was assessed using the 5-item EuroQOL questionnaire (EQ5D), which consists of 5 items and a visual analog scale (VAS). EQ5D index values were estimated from the EQ5D items using the time tradeoff approach based on Canadian norms. Tobit regression and quantile regression models were used to evaluate the adjusted effect of tenecteplase versus alteplase treatment on the EQ5D index values and VAS score, respectively. The association between return to prebaseline stroke functioning and the modified Rankin Scale score 0 to 1 and HRQOL was quantified using correlation coefficient (r) with 95% CI.

RESULTS

Of 1577 included in the intention-to-treat analysis patients, 1503 (95.3%) had complete data on the EQ5D. Of this, 769 (51.2%) were administered tenecteplase and 717 (47.7%) were female. The mean EQ5D VAS score and EQ5D index values were not significantly higher for those who received intravenous tenecteplase compared with those who received intravenous alteplase (P=0.10). Older age (P<0.01), more severe stroke assessed using the National Institutes of Health Stroke Scale (P<0.01), and longer stroke onset-to-needle time (P=0.004) were associated with lower EQ5D index and VAS scores. There was a strong association (r, 0.85 [95% CI, 0.81-0.89]) between patient-reported return to prebaseline functioning and modified Rankin Scale score 0 to 1 Similarly, there was a moderate association between return to prebaseline functioning and EQ5D index (r, 0.45 [95% CI, 0.40-0.49]) and EQ5D VAS scores (r, 0.42 [95% CI, 0.37-0.46]).

CONCLUSIONS

Although there is no differential effect of thrombolysis type on patient-reported global HRQOL and EQ 5D-5L index values in patients with acute stroke, sex- and age-related differences in HRQOL were noted in this study.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03889249.

Sex-Based Analysis of Workflow and Outcomes in Acute Ischemic Stroke Patients Treated With Alteplase Versus Tenecteplase

BACKGROUND

Understanding sex differences in stroke care is important in reducing potential disparities. Our objective was to explore sex differences in workflow efficiency, treatment efficacy, and safety in the AcT trial (Alteplase Compared to Tenecteplase).

METHODS

AcT was a multicenter, registry-linked randomized noninferiority trial comparing tenecteplase (0.25 mg/kg) with alteplase (0.9 mg/kg) in acute ischemic stroke within 4.5 hours of onset. In this post hoc analysis, baseline characteristics, workflow times, successful reperfusion (extended Thrombolysis in Cerebral Infarction score ≥2b), symptomatic intracerebral hemorrhage, 90-day functional independence (modified Rankin Scale score, 0-1), and 90-day mortality were compared by sex. Mixed-effects regression analysis was used adjusting for age, stroke severity, and occlusion site for outcomes.

RESULTS

Of 1577 patients treated with intravenous thrombolysis (2019-2022), 755 (47.9%) were women. Women were older (median, 77 [68-86] years in women versus 70 [59-79] years in men) and had a higher proportion of severe strokes (National Institutes of Health Stroke Scale score >15; 32.4% versus 24.9%) and large vessel occlusions (28.7% versus 21.5%) compared with men. All workflow times were comparable between sexes. Women were less likely to achieve functional independence (31.7% versus 39.8%; unadjusted relative risk, 0.80 [95% CI, 0.70-0.91]) and had higher mortality (17.7% versus 13.3%; unadjusted relative risk, 1.33 [95% CI, 1.06-1.69]). Adjusted analysis showed no difference in outcomes between sexes.

CONCLUSIONS

Differences in prognostic factors of age, stroke severity, and occlusion site largely accounted for higher functional dependence and mortality in women. No sex disparities were apparent in workflow quality indicators. Given the integration of the AcT trial into clinical practice, these results provide reassurance that no major sex biases are apparent in acute stroke management throughout participating Canadian centers.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03889249.

Presenting Symptoms and Diffusion-Weighted MRI Positivity by Time After Transient Neurologic Events: A Pooled Analysis of 3 Cohort Studies

BACKGROUND AND OBJECTIVE

The association between focal vs nonfocal presenting symptom and diffusion-weighted imaging (DWI) positivity in relation to onset-to-imaging time in patients with transient neurologic events remains unclear. We hypothesize that episodes consisting of focal symptoms would have proportionally higher DWI-positive imaging at later onset-to-imaging times.

METHODS

Patients with transient neurologic symptoms and a normal neurologic examination who had DWI in the combined data set of 3 cohort studies were included. We used logistic regression models to evaluate the association between each type of presenting symptom (motor weakness, speech impairment, sensory symptoms, vision loss, diplopia, gait instability, dizziness, headache, presyncope, and amnesia) and DWI positivity after adjusting for clinical variables (age, sex, history of stroke, dyslipidemia, coronary artery disease, atrial fibrillation, symptoms duration [<10, 10-59, ≥60 minutes, or unclear], and study source). We stratified the results by onset-to-imaging time categories (<6 hours, 6-23 hours, and ≥24 hours).

RESULTS

Of the total 2,411 patients (1,345 male, median age 68 years), DWI-positive lesions were detected in 598 patients (24.8%). The prevalence of DWI positivity was highest in those with motor weakness (34.7%), followed by speech impairment (33.5%). In a multivariable analysis, the presence of motor weakness, speech impairment, and sensory symptoms was associated with DWI positivity, while vision loss and headache were associated with lower odds of DWI positivity, but nevertheless had 13.6% and 15.3% frequency of DWI positive. The odds of being DWI positive varied by onset-to-imaging time categories for motor weakness, with greater odds of being DWI positive at later imaging time (<6 hours: odds ratio [OR] 1.25, 95% confidence interval [CI] 0.84-1.87; 6-23 hours: OR 2.24, 95% CI 1.47-3.42; and ≥24 hours: OR 2.42, 95% CI 1.74-3.36; interaction p = 0.033). Associations of other symptoms with DWI positivity did not vary significantly by time categories.

DISCUSSION

We found that onset-to-imaging time influences the relationship between motor weakness and DWI positivity in patients with transient neurologic events. Compared with motor, speech, and sensory symptoms, visual or nonfocal symptoms carry a lower but still a substantive association with DWI positivity.

Predicting outcome in acute stroke with large vessel occlusion-application and validation of MR PREDICTS in the ESCAPE-NA1 population

BACKGROUND

Predicting outcome after endovascular treatment for acute ischemic stroke is challenging. We aim to investigate differences between predicted and observed outcomes in patients with acute ischemic stroke treated with endovascular treatment and to evaluate the performance of a validated outcome prediction score.

PATIENTS AND METHODS

MR PREDICTS is an outcome prediction tool based on a logistic regression model designed to predict the treatment benefit of endovascular treatment based on the MR CLEAN and HERMES populations. ESCAPE-NA1 is a randomized trial of nerinetide vs. placebo in patients with acute stroke and large vessel occlusion. We applied MR PREDICTS to patients in the control arm of ESCAPE-NA1. Model performance was assessed by calculating its discriminative ability and calibration.

RESULTS

Overall, 556/1105 patients (50.3%) in the ESCAPE-NA1-trial were randomized to the control arm, 435/556 (78.2%) were treated within 6 h of symptom onset. Good outcome (modified Rankin scale 0-2) at 3 months was achieved in 275/435 patients (63.2%), the predicted probability of good outcome was 52.5%. Baseline characteristics were similar in the study and model derivation cohort except for age (ESCAPE-NA1: mean: 70 y vs. HERMES: 66 y), hypertension (72% vs. 57%), and collaterals (good collaterals, 15% vs. 44%). Compared to HERMES we observed higher rates of successful reperfusion (TICI 2b-3, ESCAPE-NA1: 87% vs. HERMES: 71%) and faster times from symptom onset to reperfusion (median: 201 min vs. 286 min). Model performance was good, indicated by a c-statistic of 0.76 (95%confidence interval: 0.71-0.81).

CONCLUSION

Outcome-prediction using models created from HERMES data, based on information available in the emergency department underestimated the actual outcome in patients with acute ischemic stroke and large vessel occlusion receiving endovascular treatment despite overall good model performance, which might be explained by differences in quality of and time to reperfusion. These findings underline the importance of timely and successful reperfusion for functional outcomes in acute stroke patients.

Symptomatic Non-stenotic Carotid Disease in Embolic Stroke of Undetermined Source : Analysis of the ESCAPE-NA1 Trial

PURPOSE

Non-stenotic (< 50%) carotid disease may play an important etiological role in ischemic stroke classified as embolic stroke of undetermined source (ESUS). We aimed to assess the prevalence of non-stenotic carotid disease and its association with ipsilateral ischemic stroke.

METHODS

Data are from ESCAPE-NA1, a randomized controlled trial investigating the neuroprotectant nerinetide in patients with acute ischemic stroke and large vessel occlusion (LVO). The degree of stenosis of the extracranial internal carotid artery (ICA) and high-risk plaque features were assessed on baseline computed tomography (CT) angiography. We evaluated the association of non-stenotic carotid disease and ipsilateral stroke by age-adjusted and sex-adjusted logistic regression and calculated the attributable risk of ipsilateral stroke caused by non-stenotic carotid disease.

RESULTS

After excluding patients with non-assessable imaging, symptomatic > 50% carotid stenosis and extracranial dissection, 799/1105 (72.1%) patients enrolled in ESCAPE-NA1 remained for this analysis. Of these, 127 (15.9%) were classified as ESUS. Non-stenotic carotid disease occurred in 34/127 ESUS patients (26.8%) and was associated with the presence of ipsilateral ischemic stroke (odds ratio, OR 1.6, 95% confidence interval, CI 1.0-2.6, p = 0.049). The risk of ipsilateral ischemic stroke attributable to non-stenotic carotid disease in ESUS was estimated to be 19.7% (95% CI -5.7% to 39%), the population attributable risk was calculated as 4.3%. Imaging features such as plaque thickness, plaque irregularity or plaque ulceration were not different between non-stenotic carotids with vs. without ipsilateral stroke.

CONCLUSION

Non-stenotic carotid disease frequently occurs in patients classified as ESUS and is associated with ipsilateral ischemic stroke. Our findings support the role of non-stenotic carotid disease as stroke etiology in ESUS, but further prospective research is needed to prove a causal relationship.

Prevalence of high-risk aortic arch atherosclerosis features on computed tomography angiography in embolic stroke of undetermined source

INTRODUCTION

Embolic stroke of undetermined source (ESUS) comprises a heterogenous group. There is a need to further identify etiologies within this group to guide management strategies. We examined the prevalence of aortic arch atherosclerosis (AAA) on CT angiography (CTA) in patients with embolic stroke of undetermined source (ESUS) to characterize high-risk plaque features.

METHODS

All patients from two prospective multicenter acute ischemic stroke studies (INTERRSeCT and PRove-IT) were included if the CTA adequately imaged the proximal aortic arch and the stroke etiology was recorded. Three readers blinded to stroke etiology analyzed the following AAA plaque features on baseline CTA at the time of stroke: 1) thickness in millimetres (mm); 2) morphology (none, smooth, ulcerated, or protruding); 3) location within the aortic arch (proximal, transverse, or distal); and 4) calcification (none, single small, multiple small, single large, or diffuse extensive).

RESULTS

We included 1063 patients, of which 293 (27.6%) had ESUS (mean age 67.5 years; 46.4% men; median NIHSS 12; 80.6% large vessel occlusion). Mean AAA thickness was significantly larger in ESUS patients (3.8 mm) compared to non-ESUS patients (3.0 mm; p<0.0001) and to a subgroup of patients with large artery atherosclerosis (2.9 mm; p=0.003). ESUS patients had a significantly higher proportion of ulcerated or protruding plaques (17.4% vs 10.3%; risk ratio 1.7, 95% C.I. 1.2-2.4, p=0.002). The location of AAA in the ESUS group was the ascending aorta in 37.9%, transverse arch in 42.3%, and descending aorta in 84.6%. Although AAA was mostly located in the distal aortic arch, ulcerated or protruding plaques were least common in the distal arch (p=0.002). There was no difference between ESUS and non-ESUS patients in plaque location (p=0.23) or calcification grade (p=0.092).

CONCLUSION

ESUS patients in our study had thicker AAA and a higher prevalence of ulcerated or protruding plaques located more proximally within the aortic arch. High-risk plaque features may suggest a causal role of AAA in the ESUS population with visible intracranial occlusions.

Effect of Time to Thrombolysis on Clinical Outcomes in Patients With Acute Ischemic Stroke Treated With Tenecteplase Compared to Alteplase: Analysis From the AcT Randomized Controlled Trial

BACKGROUND

The AcT (Alteplase Compared to Tenecteplase) randomized controlled trial showed that tenecteplase is noninferior to alteplase in treating patients with acute ischemic stroke within 4.5 hours of symptom onset. The effect of time to treatment on clinical outcomes with alteplase is well known; however, the nature of this relationship is yet to be described with tenecteplase. We assessed whether the association of time to thrombolysis treatment with clinical outcomes in patients with acute ischemic stroke differs by whether they receive intravenous tenecteplase versus alteplase.

METHODS

Patients included were from AcT, a pragmatic, registry-linked, phase 3 randomized controlled trial comparing intravenous tenecteplase to alteplase in patients with acute ischemic stroke. Eligible patients were >18 years old, with disabling neurological deficits, presenting within 4.5 hours of symptom onset, and eligible for thrombolysis. Primary outcome was modified Rankin Scale score 0 to 1 at 90 days. Safety outcomes included 24-hour symptomatic intracerebral hemorrhage and 90-day mortality rates. Mixed-effects logistic regression was used to assess the following: (a) the association of stroke symptom onset to needle time; (b) door (hospital arrival) to needle time with outcomes; and (c) if these associations were modified by type of thrombolytic administered (tenecteplase versus alteplase), after adjusting for age, sex, baseline stroke severity, and site of intracranial occlusion.

RESULTS

Of the 1538 patients included in this analysis, 1146 (74.5%; 591 tenecteplase and 555 alteplase) presented within 3 hours versus 392 (25.5%; 196: TNK and 196 alteplase) who presented within 3 to 4.5 hours of symptom onset. Baseline patient characteristics in the 0 to 3 hours versus 3- to 4.5-hour time window were similar, except patients in the 3- to 4.5-hour window had lower median baseline National Institutes of Health Stroke Severity Scale (10 versus 7, respectively) and lower proportion of patients with large vessel occlusion on baseline CT angiography (26.9% versus 18.7%, respectively). Type of thrombolytic agent (tenecteplase versus alteplase) did not modify the association between continuous onset to needle time (Pinteraction=0.161) or door-to-needle time (Pinteraction=0.972) and primary clinical outcome. Irrespective of the thrombolytic agent used, each 30-minute reduction in onset to needle time was associated with a 1.8% increase while every 10 minutes reduction in door-to-needle time was associated with a 0.2% increase in the probability of achieving 90-day modified Rankin Scale score 0 to 1, respectively.

CONCLUSIONS

The effect of time to tenecteplase administration on clinical outcomes is like that of alteplase, with faster administration resulting in better clinical outcomes.

REGISTRATION

URL: https://classic.

CLINICALTRIALS

gov; Unique identifier: NCT03889249.

Study of Rivaroxaban for Cerebral Venous Thrombosis: A Randomized Controlled Feasibility Trial Comparing Anticoagulation With Rivaroxaban to Standard-of-Care in Symptomatic Cerebral Venous Thrombosis

BACKGROUND

Emerging data suggest that direct oral anticoagulants may be a suitable choice for anticoagulation for cerebral venous thrombosis (CVT). However, conducting high-quality trials in CVT is challenging as it is a rare disease with low rates of adverse outcomes such as major bleeding and functional dependence. To facilitate the design of future CVT trials, SECRET (Study of Rivaroxaban for Cerebral Venous Thrombosis) assessed (1) the feasibility of recruitment, (2) the safety of rivaroxaban compared with standard-of-care anticoagulation, and (3) patient-centered functional outcomes.

METHODS

This was a phase II, prospective, open-label blinded-end point 1:1 randomized trial conducted at 12 Canadian centers. Participants were aged ≥18 years, within 14 days of a new diagnosis of symptomatic CVT, and suitable for oral anticoagulation; they were randomized to receive rivaroxaban 20 mg daily, or standard-of-care anticoagulation (warfarin, target international normalized ratio, 2.0-3.0, or low-molecular-weight heparin) for 180 days, with optional extension up to 365 days. Primary outcomes were annual rate of recruitment (feasibility); and a composite of symptomatic intracranial hemorrhage, major extracranial hemorrhage, or mortality at 180 days (safety). Secondary outcomes included recurrent venous thromboembolism, recanalization, clinically relevant nonmajor bleeding, and functional and patient-reported outcomes (modified Rankin Scale, quality of life, headache, mood, fatigue, and cognition) at days 180 and 365.

RESULTS

Fifty-five participants were randomized. The rate of recruitment was 21.3 participants/year; 57% of eligible candidates consented. Median age was 48.0 years (interquartile range, 38.5-73.2); 66% were female. There was 1 primary event (symptomatic intracranial hemorrhage), 2 clinically relevant nonmajor bleeding events, and 1 recurrent CVT by day 180, all in the rivaroxaban group. All participants in both arms had at least partial recanalization by day 180. At enrollment, both groups on average reported reduced quality of life, low mood, fatigue, and headache with impaired cognitive performance. All metrics improved markedly by day 180.

CONCLUSIONS

Recruitment targets were reached, but many eligible participants declined randomization. There were numerically more bleeding events in patients taking rivaroxaban compared with control, but rates of bleeding and recurrent venous thromboembolism were low overall and in keeping with previous studies. Participants had symptoms affecting their well-being at enrollment but improved over time.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03178864.

CT Perfusion Does Not Modify the Effect of Reperfusion in Patients with Acute Ischemic Stroke Undergoing Endovascular Treatment in the ESCAPE-NA1 Trial

BACKGROUND AND PURPOSE

Although reperfusion is associated with improved outcomes in patients with acute ischemic stroke undergoing endovascular treatment, many patients still do poorly. We investigated whether CTP modifies the effect of near-complete reperfusion on clinical outcomes, ie, whether poor clinical outcomes despite near-complete reperfusion can be partly or fully explained by CTP findings.

MATERIALS AND METHODS

Data are from the Safety and Efficacy of Nerinetide in Subjects Undergoing Endovascular Thrombectomy for Stroke (ESCAPE-NA1) trial. Admission CTP was processed using RAPID software, generating relative CBF and CBV volume maps at standard thresholds. CTP lesion volumes were compared in patients with-versus-without near-complete reperfusion. Associations between each CTP metric and clinical outcome (90-day mRS) were tested using multivariable logistic regression, adjusted for baseline imaging and clinical variables. Treatment-effect modification was assessed by introducing CTP lesion volume × reperfusion interaction terms in the models.

RESULTS

CTP lesion volumes and reperfusion status were available in 410/1105 patients. CTP lesion volumes were overall larger in patients without near-complete reperfusion, albeit not always statistically significant. Increased CBF <34%, CBV <34%, CBV <38%, and CBV <42% lesion volumes were associated with worse clinical outcome (ordinal mRS) at 90 days. CTP core lesion volumes did not modify the treatment effect of near-complete recanalization on clinical outcome.

CONCLUSIONS

CTP did not modify the effect of near-complete reperfusion on clinical outcomes. Thus, CTP cannot explain why some patients with near-complete reperfusion have poor clinical outcomes.

Endovascular therapy in acute ischemic stroke with poor reperfusion is associated with worse outcomes compared with best medical management: a HERMES substudy

BACKGROUND

Functional outcomes in patients with acute ischemic stroke (AIS) with large vessel occlusion (LVO) undergoing endovascular treatment (EVT) with poor reperfusion were compared with patients with AIS-LVO treated with best medical management only.

METHODS

Data are from the HERMES collaboration, a patient-level meta-analysis of seven randomized EVT trials. Baseline characteristics and functional outcomes (modified Rankin Scale (mRS) score at 90 days) were compared between patients with poor reperfusion (defined as modified Thrombolysis in Cerebral Infarction Score 0-1 on the final intracranial angiography run as assessed by the central imaging core laboratory) and patients in the control arm with multivariable logistic ordinal logistic regression adjusted for pre-specified baseline variables.

RESULTS

972 of 1764 patients from the HERMES collaboration were included in the analysis: 893 in the control arm and 79 in the EVT arm with final mTICI 0-1. Patients with poor reperfusion who underwent EVT had higher baseline National Institutes of Health Stroke Scale than controls (median 19 (IQR 15.5-21) vs 17 (13-21), P=0.011). They also had worse mRS at 90 days compared with those in the control arm in adjusted analysis (median 4 (IQR 3-6) vs median 4 (IQR 2-5), adjusted common OR 0.59 (95% CI 0.38 to 0.91)). Symptomatic intracranial hemorrhage was not different between the two groups (3.9% vs 3.5%, P=0.75, adjusted OR 0.94 (95% CI 0.23 to 3.88)).

CONCLUSION

Poor reperfusion after EVT was associated with worse outcomes than best medical management, although no difference in symptomatic intracranial hemorrhage was seen. These results emphasize the need for additional efforts to further improve technical EVT success rates.

Development and Validation of a Postprocedural Model to Predict Outcome After Endovascular Treatment for Ischemic Stroke

Importance

Outcome prediction after endovascular treatment (EVT) for ischemic stroke is important to patients, family members, and physicians.

Objective

To develop and validate a model based on preprocedural and postprocedural characteristics to predict functional outcome for individual patients after EVT.

Design, Setting, and Participants

A prediction model was developed using individual patient data from 7 randomized clinical trials, performed between December 2010 and December 2014. The model was developed within the Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke Trials (HERMES) collaboration and external validation in data from the Dutch Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands (MR CLEAN) Registry of patients treated in clinical practice between March 2014 and November 2017. Participants included patients from multiple centers throughout different countries in Europe, North America, East Asia, and Oceania (derivation cohort), and multiple centers in the Netherlands (validation cohort). Included were adult patients with a history of ischemic stroke from an intracranial large vessel occlusion in the anterior circulation who underwent EVT within 12 hours of symptom onset or last seen well. Data were last analyzed in July 2022.

Main Outcome(s) and Measure(s)

A total of 19 variables were assessed by multivariable ordinal regression to predict functional outcome (modified Rankin Scale [mRS] score) 90 days after EVT. Variables were routinely available 1 day after EVT. Akaike information criterion (AIC) was used to optimize model fit vs model complexity. Probabilities for functional independence (mRS 0-2) and survival (mRS 0-5) were derived from the ordinal model. Model performance was expressed with discrimination (C statistic) and calibration.

Results

A total of 781 patients (median [IQR] age, 67 [57-76] years; 414 men [53%]) constituted the derivation cohort, and 3260 patients (median [IQR] age, 72 [61-80] years; 1684 men [52%]) composed the validation cohort. Nine variables were included in the model: age, baseline National Institutes of Health Stroke Scale (NIHSS) score, prestroke mRS score, history of diabetes, occlusion location, collateral score, reperfusion grade, NIHSS score at 24 hours, and symptomatic intracranial hemorrhage 24 hours after EVT. External validation in the MR CLEAN Registry showed excellent discriminative ability for functional independence (C statistic, 0.91; 95% CI, 0.90-0.92) and survival (0.89; 95% CI, 0.88-0.90). The proportion of functional independence in the MR CLEAN Registry was systematically higher than predicted by the model (41% vs 34%), whereas observed and predicted survival were similar (72% vs 75%). The model was updated and implemented for clinical use.

Conclusion and relevance

The prognostic tool MR PREDICTS@24H can be applied 1 day after EVT to accurately predict functional outcome for individual patients at 90 days and to provide reliable outcome expectations and personalize follow-up and rehabilitation plans. It will need further validation and updating for contemporary patients.

Effect of Needle-To-Puncture Time on Reperfusion Outcome in Acute Ischemic Stroke

INTRODUCTION

The aim of the study was to investigate the impact of time interval between start of intravenous thrombolysis (IVT) to start of endovascular thrombectomy (EVT) on stroke outcomes.

METHODS

Data from the Quality Improvement and Clinical Research (QuICR) provincial stroke registry from Alberta, Canada, were used to identify stroke patients who received IVT and EVT from January 2015 to December 2019. We assessed the impact of the time interval between IVT bolus to EVT puncture (needle-to-puncture times [NPT]) on outcomes. Radiological outcomes included successful initial recanalization (revised Arterial Occlusive Lesion 2b-3), successful initial and final reperfusion (modified thrombolysis in cerebral infarction 2b-3). Clinical outcomes were 90-day modified Rankin Scale (mRS) and mortality.

RESULTS

Of the 680 patients, 233 patients (median age: 73, 41% females) received IVT + EVT. Median NPT was 38 min (IQR, 24-60). Arrival during working hours was independently associated with shorter NPT (p < 0.001). Successful initial recanalization and initial and final reperfusion were observed in 12%, 10%, and 83% of patients, respectively. NPT was not associated with initial successful recanalization (OR 0.97 for every 10-min increase of NPT, 95% CI: 0.91-1.04), initial successful reperfusion (OR 1.01, 95% CI: 0.96-1.07), or final successful reperfusion (OR: 1.03, 95% CI: 0.97-1.08). Every 10-min delay in NPT was associated with lower odds of functional independence at 90 days (mRS ≤2; OR: 0.93; 95% CI, 0.88-0.97). Patients with shorter NPT (≤38 min) had lower 90-day mRS scores (median 1 vs. 3; OR: 0.54 [0.31-0.91]) and had lower mortality (6.1% vs. 21.2%; OR, 0.23 [0.10-0.57]) than the longer NPT group.

CONCLUSION

Shorter NPT did not impact reperfusion outcomes but was associated with better clinical outcome.

Effect of incomplete reperfusion patterns on clinical outcome: insights from the ESCAPE-NA1 trial

BACKGROUND

Incomplete reperfusion (IR) after mechanical thrombectomy (MT) can be a consequence of residual occlusion, no-reflow phenomenon, or collateral counterpressure. Data on the impact of these phenomena on clinical outcome are limited.

METHODS

Patients from the ESCAPE-NA1 trial with IR (expanded Thrombolysis In Cerebral Infarction (eTICI) 2b) were compared with those with complete or near-complete reperfusion (eTICI 2c-3) on the final angiography run. Final runs were assessed for (a) an MT-accessible occlusion, or (b) a non-MT-accessible occlusion pattern. The primary clinical outcome was modified Rankin Scale (mRS) 0-2 at 90 days. Our imaging outcome was infarction in IR territory on follow-up imaging. Unadjusted and adjusted incidence rate ratios (aIRR) with 95% confidence intervals (95% CI) were obtained.

RESULTS

Of 1105 patients, 443 (40.1%) with IR and 506 (46.1%) with complete or near-complete reperfusion were included. An MT-accessible occlusion was identified in 147/443 patients (33.2%) and a non-MT-accessible occlusion in 296/443 (66.8%). As compared with patients with near-complete/complete reperfusion, patients with IR had significantly lower chances of achieving mRS 0-2 at 90 days (aIRR 0.82, 95% CI 0.74 to 0.91). Rates of mRS 0-2 were lower in the MT-accessible occlusion group as compared with the non-MT-accessible occlusion pattern group (aIRR 0.71, 95% CI 0.60 to 0.83, and aIRR 0.89, 95% CI 0.81 to 0.98, respectively). More patients with MT-accessible occlusion patterns developed infarcts in the non-reperfused territory as compared with patients with non-MT occlusion patterns (68.7% vs 46.3%).

CONCLUSION

IR was associated with worse clinical outcomes than near-complete/complete reperfusion. Two-thirds of our patients with IR had non-MT-accessible occlusion patterns which were associated with better clinical and imaging outcomes compared with those with MT-accessible occlusion patterns.

Effects of a Province-wide Triaging System for TIA: The ASPIRE Intervention

BACKGROUND AND OBJECTIVES

Urgent transient ischemic attack (TIA) management to reduce stroke recurrence is challenging, particularly in rural and remote areas. In Alberta, Canada, despite an organized stroke system, data from 1999 to 2000 suggested that stroke recurrence after TIA was as high as 9.5% at 90 days. Our objective was to determine whether a multifaceted population-based intervention resulted in a reduction in recurrent stroke after TIA.

METHODS

In this quasi-experimental health services research intervention study, we implemented a TIA management algorithm across the entire province, centered around a 24-hour physician's TIA hotline and public and health provider education on TIA. From administrative databases, we linked emergency department discharge abstracts to hospital discharge abstracts to identify incident TIAs and recurrent strokes at 90 days across a single payer system with validation of recurrent stroke events. The primary outcome was recurrent stroke; with a secondary composite outcome of recurrent stroke, acute coronary syndrome, and all-cause death. We used an interrupted time series regression analysis of age-adjusted and sex-adjusted stroke recurrence rates after TIA, incorporating a 2-year preimplementation period (2007-2009), a 15-month implementation period, and a 2-year postimplementation period (2010-2012). Logistic regression was used to examine outcomes that did not fit the time series model.

RESULTS

We assessed 6,715 patients preimplementation and 6,956 patients postimplementation. The 90-day stroke recurrence rate in the pre-Alberta Stroke Prevention in TIA and mild Strokes (ASPIRE) period was 4.5% compared with 5.3% during the post-ASPIRE period. There was neither a step change (estimate 0.38; p = 0.65) nor slope change (parameter estimate 0.30; p = 0.12) in recurrent stroke rates associated with the ASPIRE intervention implementation period. Adjusted all-cause mortality (odds ratio 0.71, 95% CI 0.56-0.89) was significantly lower after the ASPIRE intervention.

DISCUSSION

The ASPIRE TIA triaging and management interventions did not further reduce stroke recurrence in the context of an organized stroke system. The apparent lower mortality postintervention may be related to improved surveillance after events identified as TIAs, but secular trends cannot be excluded.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that a standardized population-wide algorithmic triage system for patients with TIA did not reduce recurrent stroke rate.

Infarcts in a New Territory: Insights From the ESCAPE-NA1 Trial

BACKGROUND

Infarct in a new territory (INT) is a known complication of endovascular stroke therapy. We assessed the incidence of INT, outcomes after INT, and the impact of concurrent treatments with intravenous thrombolysis and nerinetide.

METHODS

Data are from ESCAPE-NA1 trial (Safety and Efficacy of Nerinetide [NA-1] in Subjects Undergoing Endovascular Thrombectomy for Stroke), a multicenter, international randomized study that assessed the efficacy of intravenous nerinetide in subjects with acute ischemic stroke who underwent endovascular thrombectomy within 12 hours from onset. Concurrent treatment and outcomes were collected as part of the trial protocol. INTs were identified on core lab imaging review of follow-up brain imaging and defined by the presence of infarct in a new vascular territory, outside the baseline target occlusion(s) on follow-up brain imaging (computed tomography or magnetic resonance imaging). INTs were classified by maximum diameter (<2, 2-20, and >20 mm), number, and location. The association between INT and clinical outcomes (modified Rankin Scale and death) was assessed using standard descriptive techniques and adjusted estimates of effect were derived from Poisson regression models.

RESULTS

Among 1092 patients, 103 had INT (9.3%, median age 69.5 years, 49.5% females). There were no differences in baseline characteristics between those with versus without INT. Most INTs (91/103, 88.3%) were not associated with visible occlusions on angiography and 39 out of 103 (37.8%) were >20 mm in maximal diameter. The most common INT territory was the anterior cerebral artery (27.8%). Almost half of the INTs were multiple (46 subjects, 43.5%, range, 2-12). INT was associated with poorer outcomes as compared to no INT on the primary outcome of modified Rankin Scale score of 0 to 2 at 90 days (adjusted risk ratio, 0.71 [95% CI, 0.57-0.89]). Infarct volume in those with INT was greater by a median of 21 cc compared with those without, and there was a greater risk of death as compared to patients with no INT(adjusted risk ratio, 2.15 [95% CI, 1.48-3.13]).

CONCLUSIONS

Infarcts in a new territory are common in individuals undergoing endovascular thrombectomy for acute ischemic stroke and are associated with poorer outcomes. Optimal therapeutic approaches, including technical strategies, to reduce INT represent a new target for incremental quality improvement of endovascular thrombectomy.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT02930018.

Cost-effectiveness of testing for CYP2C19 loss-of-function carriers following transient ischemic attack/minor stroke: A Canadian perspective

BACKGROUND

The CHANCE-2 study compared 3 weeks of aspirin-ticagrelor to aspirin-clopidogrel in CYP2C19 loss-of-function (LOF) allele carriers following a transient ischemic attack (TIA)/minor stroke and demonstrated a modestly lower risk of stroke recurrence with aspirin-ticagrelor. This stroke protection was largely for minor stroke and came at an increased risk of bleeding. The cost-effectiveness of implementing testing for LOF allele status to personalize antiplatelet regimen for secondary stroke prevention after a TIA/minor stroke in the Canadian health care context is unknown.

METHODS

Cost-effectiveness analysis using a decision-analytic Markov cohort model with a lifetime horizon was performed to determine the costs and health benefits of testing for LOF allele status compared with no testing (current standard of care). The population of interest was patients living in Canada who suffered a TIA/minor stroke. Outcomes of interest were life-years gained (LYG), quality-adjusted life years (QALY) gained, costs (reported in 2022 Canadian dollars), and the incremental cost-effectiveness ratio (ICER). We adopted the perspective of the Federal, Provincial, and Territorial Ministries of Health and used a 1.5% annual discount rate. Sensitivity analyses were performed to assess uncertainty.

RESULTS

Compared to standard of care, LOF allele testing leads to 0.14 LYG (undiscounted), 0.12 QALYs gained (undiscounted), and additional lifetime costs of CAD$432 (discounted) per patient. The ICER of the LOF allele testing strategy is CAD$4310 per QALY gained compared with standard of care. The probabilistic sensitivity analyses demonstrated that LOF allele testing was cost-effective in more than 99.99% of simulations using a willingness-to-pay threshold of CAD$50,000 per QALY.

CONCLUSION

Based on available evidence, testing for LOF allele followed by short duration 3 weeks of aspirin-ticagrelor compared to standard-of-care aspirin-clopidogrel can lead to prolonged life and improved quality of life and can be considered very cost-effective when compared with other well-accepted technologies in health and medicine.

Admission systolic blood pressure and effect of endovascular treatment in patients with ischaemic stroke: an individual patient data meta-analysis

BACKGROUND

Current guidelines for ischaemic stroke treatment recommend a strict, but arbitrary, upper threshold of 185/110 mm Hg for blood pressure before endovascular thrombectomy. Nevertheless, whether admission blood pressure influences the effect of endovascular thrombectomy on outcome remains unknown. Our aim was to study the influence of admission systolic blood pressure (SBP) on functional outcome and on the effect of endovascular thrombectomy.

METHODS

We used individual patient data from seven randomised controlled trials (MR CLEAN, ESCAPE, EXTEND-IA, SWIFT PRIME, REVASCAT, PISTE, and THRACE) that randomly assigned patients with anterior circulation ischaemic stroke to endovascular thrombectomy (predominantly using stent retrievers) or standard medical therapy (control) between June 1, 2010, and April 30, 2015. We included all patients for whom SBP data were available at hospital admission. The primary outcome was functional outcome (modified Rankin Scale) at 90 days. We assessed the association of SBP with outcome in both the endovascular thrombectomy group and the control group using multilevel regression analysis and tested for non-linearity and for interaction between SBP and effect of endovascular thrombectomy, taking into account treatment with intravenous thrombolysis.

FINDINGS

We included 1753 patients (867 assigned to endovascular thrombectomy, 886 assigned to control) after excluding 11 patients for whom SBP data were missing. We found a non-linear association between SBP and functional outcome with an inflection point at 140 mm Hg (732 [42%] of 1753 patients had SBP <140 mm Hg and 1021 [58%] had SBP ≥140 mm Hg). Among patients with SBP of 140 mm Hg or higher, admission SBP was associated with worse functional outcome (adjusted common odds ratio [acOR] 0·86 per 10 mm Hg SBP increase; 95% CI 0·81-0·91). We found no association between SBP and functional outcome in patients with SBP less than 140 mm Hg (acOR 0·97 per 10 mm Hg SBP decrease, 95% CI 0·88-1·05). There was no significant interaction between SBP and effect of endovascular thrombectomy on functional outcome (p=0·96).

INTERPRETATION

In our meta-analysis, high admission SBP was associated with worse functional outcome after stroke, but SBP did not seem to negate the effect of endovascular thrombectomy. This finding suggests that admission SBP should not form the basis for decisions to withhold or delay endovascular thrombectomy for ischaemic stroke, but randomised trials are needed to further investigate this possibility.

FUNDING

Medtronic.

Mechanical Thrombectomy Global Access For Stroke (MT-GLASS): A Mission Thrombectomy (MT-2020 Plus) Study

BACKGROUND

Despite the well-established potent benefit of mechanical thrombectomy (MT) for large vessel occlusion (LVO) stroke, access to MT has not been studied globally. We conducted a worldwide survey of countries on 6 continents to define MT access (MTA), the disparities in MTA, and its determinants on a global scale.

METHODS

Our survey was conducted in 75 countries through the Mission Thrombectomy 2020+ global network between November 22, 2020, and February 28, 2021. The primary end points were the current annual MTA, MT operator availability, and MT center availability. MTA was defined as the estimated proportion of patients with LVO receiving MT in a given region annually. The availability metrics were defined as ([current MT operators×50/current annual number of estimated thrombectomy-eligible LVOs]×100 = MT operator availability) and ([current MT centers×150/current annual number of estimated thrombectomy-eligible LVOs]×100= MT center availability). The metrics used optimal MT volume per operator as 50 and an optimal MT volume per center as 150. Multivariable-adjusted generalized linear models were used to evaluate factors associated with MTA.

RESULTS

We received 887 responses from 67 countries. The median global MTA was 2.79% (interquartile range, 0.70-11.74). MTA was <1.0% for 18 (27%) countries and 0 for 7 (10%) countries. There was a 460-fold disparity between the highest and lowest nonzero MTA regions and low-income countries had 88% lower MTA compared with high-income countries. The global MT operator availability was 16.5% of optimal and the MT center availability was 20.8% of optimal. On multivariable regression, country income level (low or lower-middle versus high: odds ratio, 0.08 [95% CI, 0.04-0.12]), MT operator availability (odds ratio, 3.35 [95% CI, 2.07-5.42]), MT center availability (odds ratio, 2.86 [95% CI, 1.84-4.48]), and presence of prehospital acute stroke bypass protocol (odds ratio, 4.00 [95% CI, 1.70-9.42]) were significantly associated with increased odds of MTA.

CONCLUSIONS

Access to MT on a global level is extremely low, with enormous disparities between countries by income level. The significant determinants of MT access are the country's per capita gross national income, prehospital LVO triage policy, and MT operator and center availability.

Risk factors of unexplained early neurological deterioration after treatment for ischemic stroke due to large vessel occlusion: a post hoc analysis of the HERMES study

BACKGROUND

Early neurological deterioration (END) after endovascular treatment (EVT) in patients with anterior circulation acute ischemic stroke (AIS) is associated with poor outcome. END may remain unexplained by parenchymal hemorrhage (UnEND). We aim to analyze the risk factors of UnEND in the medical management (MM) and EVT arms of the HERMES study.

METHODS

We conducted a post-hoc analysis of anterior AIS patients who underwent EVT for proximal anterior occlusions. Risk factors of UnEND, defined as a worsening of ≥4 points between baseline National Institutes of Health Stroke Scale (NIHSS) and NIHSS at 24 hours without hemorrhage, were compared between both arms using mixed logistic regression models adjusted for baseline characteristics. An interaction analysis between the EVT and MM arms for risk factors of UnEND was conducted.

RESULTS

Among 1723 patients assessable for UnEND, 160 patients experienced an UnEND (9.3%), including 9.1% (78/854) in the EVT arm and 9.4% (82/869) in the MM arm. There was no significant difference in the incidence of UnEND between the two study arms. In the EVT population, independent risk factors of UnEND were lower baseline NIHSS, higher baseline glucose, and lower collateral grade. In the MM population, the only independent predictor of UnEND was higher baseline glucose. However, we did not demonstrate an interaction between EVT and MM for baseline factors as risk factors of UnEND. UnEND was, similarly in both treatment groups, a significant predictor of unfavorable outcome in both the EVT (p<0.001) and MM (p<0.001) arms.

CONCLUSIONS

UnEND is not an uncommon event, with a similar rate which ever treatment arm is considered. In the clinical scenario of AIS due to large vessel occlusion, no patient-related factor seems to increase the risk for UnEND when treated by EVT compared with MM.

Clinical outcome of patients with mild pre-stroke morbidity following endovascular treatment: a HERMES substudy

BACKGROUND

Analyses of the effect of pre-stroke functional levels on the outcome of endovascular therapy (EVT) have focused on the course of patients with moderate to substantial pre-stroke disability. The effect of complete freedom from pre-existing disability (modified Rankin Scale (mRS) 0) versus predominantly mild pre-existing disability/symptoms (mRS 1-2) has not been well delineated.

METHODS

The HERMES meta-analysis pooled data from seven randomized trials that tested the efficacy of EVT. We tested for a multiplicative interaction effect of pre-stroke mRS on the relationship between treatment and outcomes. Ordinal regression was used to assess the association between EVT and 90-day mRS (primary outcome) in the subgroup of patients with pre-stroke mRS 1-2. Multivariable regression modeling was then used to test the effect of mild pre-stroke disability/symptoms on the primary and secondary outcomes (delta-mRS, mRS 0-2/5-6) compared with patients with pre-stroke mRS 0.

RESULTS

We included 1764 patients, of whom 199 (11.3%) had pre-stroke mRS 1-2. No interaction effect of pre-stroke mRS on the relationship between treatment and outcome was observed. Patients with pre-stroke mRS 1-2 had worse outcomes than those with pre-stroke mRS 0 (adjusted common OR (acOR) 0.53, 95% CI 0.40 to 0.70). Nonetheless, a significant benefit of EVT was observed within the mRS 1-2 subgroup (cOR 2.08, 95% CI 1.22 to 3.55).

CONCLUSIONS

Patients asymptomatic/without disability prior to onset have better outcomes following EVT than patients with mild disability/symptoms. Patients with pre-stroke mRS 1-2, however, more often achieve good outcomes with EVT compared with conservative management. These findings indicate that mild pre-existing disability/symptoms influence patient prognosis after EVT but do not diminish the EVT treatment effect.

Outcome prediction in large vessel occlusion ischemic stroke with or without endovascular stroke treatment: THRIVE-EVT

INTRODUCTION

The THRIVE score and the THRIVE-c calculation are validated ischemic stroke outcome prediction tools based on patient variables that are readily available at initial presentation. Randomized controlled trials (RCTs) have demonstrated the benefit of endovascular treatment (EVT) for many patients with large vessel occlusion (LVO), and pooled data from these trials allow for adaptation of the THRIVE-c calculation for use in shared clinical decision making regarding EVT.

METHODS

To extend THRIVE-c for use in the context of EVT, we extracted data from the Virtual International Stroke Trials Archive (VISTA) from 7 RCTs of EVT. Models were built in a randomly selected development cohort using logistic regression that included the predictors from THRIVE-c: age, NIH Stroke Scale (NIHSS) score, presence of hypertension, diabetes mellitus, and/or atrial fibrillation, as well as randomization to EVT and, where available, the Alberta Stroke Program Early CT Score (ASPECTS).

RESULTS

Good outcome was achieved in 366/787 (46.5%) of subjects randomized to EVT and in 236/795 (29.7%) of subjects randomized to control (P < 0.001), and the improvement in outcome with EVT was seen across age, NIHSS, and THRIVE-c good outcome prediction. Models to predict outcome using THRIVE elements (age, NIHSS, and comorbidities) together with EVT, with or without ASPECTS, had similar performance by ROC analysis in the development and validation cohorts (THRIVE-EVT ROC area under the curve (AUC) = 0.716 in development, 0.727 in validation, P = 0.30; THRIVE-EVT + ASPECTS ROC AUC = 0.718 in development, 0.735 in validation, P = 0.12).

CONCLUSION

THRIVE-EVT may be used alongside the original THRIVE-c calculation to improve outcome probability estimation for patients with acute ischemic stroke, including patients with or without LVO, and to model the potential improvement in outcomes with EVT for an individual patient based on variables that are available at initial presentation. Online calculators for THRIVE-c estimation are available at www.thrivescore.org and www.mdcalc.com/thrive-score-for-stroke-outcome.

Effects of intensive blood pressure lowering on cerebral ischaemia in thrombolysed patients: insights from the ENCHANTED trial

Background

Intensive blood pressure lowering may adversely affect evolving cerebral ischaemia. We aimed to determine whether intensive blood pressure lowering altered the size of cerebral infarction in the 2196 patients who participated in the Enhanced Control of Hypertension and Thrombolysis Stroke Study, an international randomised controlled trial of intensive (systolic target 130-140 mm Hg within 1 h; maintained for 72 h) or guideline-recommended (systolic target <180 mm Hg) blood pressure management in patients with hypertension (systolic blood pressure >150 mm Hg) after thrombolysis treatment for acute ischaemic stroke between March 3, 2012 and April 30, 2018.

Methods

All available brain imaging were analysed centrally by expert readers. Log-linear regression was used to determine the effects of intensive blood pressure lowering on the size of cerebral infarction, with adjustment for potential confounders. The primary analysis pertained to follow-up computerised tomography (CT) scans done between 24 and 36 h. Sensitivity analysis were undertaken in patients with only a follow-up magnetic resonance imaging (MRI) and either MRI or CT at 24-36 h, and in patients with any brain imaging done at any time during follow-up. This trial is registered with ClinicalTrials.gov, number NCT01422616.

Findings

There were 1477 (67.3%) patients (mean age 67.7 [12.1] y; male 60%, Asian 65%) with available follow-up brain imaging for analysis, including 635 patients with a CT done at 24-36 h. Mean achieved systolic blood pressures over 1-24 h were 141 mm Hg and 149 mm Hg in the intensive group and guideline group, respectively. There was no effect of intensive blood pressure lowering on the median size (ml) of cerebral infarction on follow-up CT at 24-36 h (0.3 [IQR 0.0-16.6] in the intensive group and 0.9 [0.0-12.5] in the guideline group; log Δmean -0.17, 95% CI -0.78 to 0.43). The results were consistent in sensitivity and subgroup analyses.

Interpretation

Intensive blood pressure lowering treatment to a systolic target <140 mm Hg within several hours after the onset of symptoms may not increase the size of cerebral infarction in patients who receive thrombolysis treatment for acute ischaemic stroke of mild to moderate neurological severity.

Funding

National Health and Medical Research Council of Australia; UK Stroke Association; UK Dementia Research Institute; Ministry of Health and the National Council for Scientific and Technological Development of Brazil; Ministry for Health, Welfare, and Family Affairs of South Korea; Takeda.

Time Course of Early Hematoma Expansion in Acute Spot-Sign Positive Intracerebral Hemorrhage: Prespecified Analysis of the SPOTLIGHT Randomized Clinical Trial

BACKGROUND

In the SPOTLIGHT trial (Spot Sign Selection of Intracerebral Hemorrhage to Guide Hemostatic Therapy), patients with a computed tomography (CT) angiography spot-sign positive acute intracerebral hemorrhage were randomized to rFVIIa (recombinant activated factor VIIa; 80 μg/kg) or placebo within 6 hours of onset, aiming to limit hematoma expansion. Administration of rFVIIa did not significantly reduce hematoma expansion. In this prespecified analysis, we aimed to investigate the impact of delays from baseline imaging to study drug administration on hematoma expansion.

METHODS

Hematoma volumes were measured on the baseline CT, early post-dose CT, and 24 hours CT scans. Total hematoma volume (intracerebral hemorrhage+intraventricular hemorrhage) change between the 3 scans was calculated as an estimate of how much hematoma expansion occurred before and after studying drug administration.

RESULTS

Of the 50 patients included in the trial, 44 had an early post-dose CT scan. Median time (interquartile range) from onset to baseline CT was 1.4 hours (1.2-2.6). Median time from baseline CT to study drug was 62.5 (55-80) minutes, and from study drug to early post-dose CT was 19 (14.5-30) minutes. Median (interquartile range) total hematoma volume increased from baseline CT to early post-dose CT by 10.0 mL (-0.7 to 18.5) in the rFVIIa arm and 5.4 mL (1.8-8.3) in the placebo arm (P=0.96). Median volume change between the early post-dose CT and follow-up scan was 0.6 mL (-2.6 to 8.3) in the rFVIIa arm and 0.7 mL (-1.6 to 2.1) in the placebo arm (P=0.98). Total hematoma volume decreased between the early post-dose CT and 24-hour scan in 44.2% of cases (rFVIIa 38.9% and placebo 48%). The adjusted hematoma growth in volume immediately post dose for FVIIa was 0.998 times that of placebo ([95% CI, 0.71-1.43]; P=0.99). The hourly growth in FFVIIa was 0.998 times that for placebo ([95% CI, 0.994-1.003]; P=0.50; Table 3).

CONCLUSIONS

In the SPOTLIGHT trial, the adjusted hematoma volume growth was not associated with Factor VIIa treatment. Most hematoma expansion occurred between the baseline CT and the early post-dose CT, limiting any potential treatment effect of hemostatic therapy. Future hemostatic trials must treat intracerebral hemorrhage patients earlier from onset, with minimal delay between baseline CT and drug administration.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT01359202.

Generalizability of the REDUCE-IT trial to South Asians with cardiovascular disease

BACKGROUND

South Asians (SAs) represent ∼25% of the world's population and account for >50% of global cardiovascular (CV) deaths, yet they continue to be underrepresented in contemporary clinical trials. The REDUCE-IT study demonstrated in a high-risk and predominantly White population that icosapent ethyl (IPE) lowered major adverse cardiovascular events by 25%. We sought to determine the generalizability of these results to a high-risk population of SAs with established CV disease living in Canada.

METHODS

This was a cross-sectional observational study of 200 statin-treated SAs (≥45 years) with atherosclerotic CV disease (ASCVD) (NCT05271591). SA ethnicity was self-identified as being of Anglo-Indian, Bangladeshi, Bengali, Bhutanese, Goan, Gujarati, Indian, Jatt, Kashmiri, Maharashtrian, Malayali, Nepali, Pakistani, Punjabi, Sindhi, Sinhalese, Sri Lankan, Tamil, Telugu, or other SA. ASCVD was defined as the presence of coronary, carotid, or peripheral atherosclerosis.

FINDINGS

Mean age of the cohort was 67 years, where 82% were men and 57% had diabetes. The predominant ASCVD phenotype was coronary artery disease (94%). Mean (SD) baseline LDL-C and triglycerides were 1.70 (0.8) mmol/L and 1.42 (1.0) mmol/L, respectively. Three-quarters were on high-intensity statin therapy. According to the Health Canada/Canadian Cardiovascular Society Guidelines and FDA-approved indication, 33% and 25% of the participants were, respectively, eligible for IPE.

CONCLUSIONS

A large proportion of high-intensity, statin-treated, high-risk patients with ASCVD and of self-reported SA ethnicity are eligible for IPE. These data have important translational implications for SAs who are at a disproportionately higher risk of CV morbidity and mortality.

FUNDING

This study was funded by an unrestricted grant provided by HLS Therapeutics Inc, Canada.

Abstract WP113: Feasibility Of Non-invasive Brain Temperature Measurement In Acute Ischemic Stroke: A Comparison Study Of MR Thermometry Vs. Zero-Heat-Flux Sensors

Introduction: Brain-selective hypothermia is a promising neuroprotectant in acute ischemic stroke. However, a non-invasive bedside method to monitor brain temperature during cooling is lacking. We tested the feasibility and accuracy of measuring brain temperature non-invasively using sensors designed to monitor core body temperature.

Methods: In this prospective single-center study, 20 patients with large or medium vessel occlusion strokes were enrolled. Patients underwent a 3T MR spectroscopy imaging (MRSI, the reference standard) and zero heat flux (ZHF) core temperature sensor measurements (3M TM Bair Hugger TM ) within 12-72 hours from admission. Two ZHF sensors were placed on each side of the forehead on the side of stroke and contralateral side and the temperatures were checked before and after MRSI. A 2x2x2 cm voxel was centered on the infarct and matching contralateral location using diffusion weighted imaging. Brain temperature on MRSI was calculated using the relative chemical shifts of water and N-acetyl aspartate. Temperature measurements of the ZHF sensors were compared to MRSI measurements.

Results: The brain temperature of stroke and contralateral sides were similar using MRSI or using ZHF sensors when each modality was compared to itself by hemisphere (all p>0.05). However, there was a significant difference for the ipsilateral side: median (SD) temperatures using MRSI was 36.0°C (1.8) vs 36.8°C (0.5) for sensor measurement. Bland-Altman plots showed that 95% of the observations fell within upper and lower limits of agreement of -2.1 to +3.7°C while 61% of observations fell within an agreement limit of +/- 1°C. There was an indication of an overall higher temperature measurements using the ZHF sensors compared to MRSI (Figure 1).

Conclusions: More studies are needed to validate the use of ZHF thermometry in ischemic stroke including studies implementing hypothermia.

Figure 1. Boxplot of stroke side MRSI compared to zero-heat-flux sensors.

Abstract 99: Clot Composition And Reperfusion Outcomes In 1430 Mechanical Thrombectomy Patients: Analysis Of The Stroke Thromboembolism Registry Of Imaging And Pathology

Background: Understanding clot composition may allow for better technical planning and improved outcomes in mechanical thrombectomy (MT). We sought to correlate clot composition with reperfusion outcomes in MT.

Methods: Clinical, imaging, and clot data from patients enrolled in the STRIP Registry from September 2016 to September 2020 were analyzed. Samples were fixed in 10% phosphate-buffered formalin and stained with hematoxylin and eosin and Martius Scarlett Blue. Percent composition, richness, and gross appearance were evaluated. Outcome measures included the rate of First-Pass Effect (mTICI2c/3, FPE) and the number of device passes.

Results: A total of 1430 patients (mean age, 68.4±13.5years; median [IQR] baseline NIHSS,17.2 [10.5-23]; IV-tPA use, 36%; Stent-Retrievers [SR], 27%; Contact Aspiration [CA], 27%; Combined SR + CA, 43%) were included. The median [IQR] number of passes was 1 [1-2]. FPE was achieved in 39.3% of the cases. There was no association between percent histological composition or clot richness and FPE in the overall population. However, the combined technique resulted in lower FPE rates for RBC-rich (P<0.0001), platelet-rich (P=0.003), and mixed (P<0.0001) clots. Fibrin-rich and platelet-rich clots required a higher number of passes compared to RBC-rich and mixed clots (median, 2 and 1.5 vs.1, respectively, P=0.02). CA displayed a trend towards a higher number of passes with fibrin-rich clots (2 vs.1, P=0.12). By gross appearance, mixed/heterogeneous clots had lower FPE rates than red and white clots.

Conclusion: Despite the lack of correlation between clot histology and FPE in the overall population, our study adds to the growing body of evidence supporting the notion that clot composition influences reperfusion treatment strategy outcomes. Additional studies are needed.

Abstract WP126: Predictors Of Intracranial Hemorrhage Volume Expansion In Patients Receiving Factor Xa Inhibitors In The Annexa-4 Trial

Introduction: Andexanet, a specific reversal agent for FXa inhibitors, showed an effective hemostasis in 82% of patients with major bleeding in the ANNEXA-4 trial. However, little is known about the predictors associated with hematoma expansion in patients with FXa inhibitor-associated intracranial hemorrhage (ICrH) receiving andexanet.

Methods: ANNEXA-4 was a prospective, single-arm, open-label study of andexanet in patients with acute major bleeding within 18h after taking a FXa inhibitor. Hematoma volumes at baseline and 12h after andexanet treatment were measured utilizing a computerized-assisted volumetric method. Univariate and multivariate logistic regression analyses of baseline clinical and non-clinical parameters were performed to identify factors predictive of different volumes of hematoma expansion.

Results: A total of 305 patients with both baseline and follow-up imaging were included (mean age 80 years; 60.2% with intracerebral hemorrhage; 55.4% taking apixaban; 32.5% taking rivaroxaban). Overall median baseline hematoma volume was 10.4 mls (IQR 2.7-28.1) and time from symptom onset to baseline CT was 3.3h (1.5-6.8). Mean baseline anti-FXa activity levels were 148 ng/mL (SD 107.5). In follow up scans, 48 cases (15.7%) showed evidence of ICrH expansion ≥6 mls. Utilizing a four category ICrH Expansion Scale as the dependent variable, ordinal logistic regression identified Glasgow Coma Scale (GCS) score (OR 0.79; 95% CI 0.64-0.97), baseline ICrH volume (OR 1.02; 95% CI 1.01-1.04) and time from symptom onset to CT (OR 0.73 (0.53-0.99) as significant predictors of ICrH expansion. Baseline anti-FXA activity (OR 1.54; 95% CI 0.95-2.51; p value 0.08) and multiple compartment ICrH (OR 2.32; 95% CI 0.98-5.51; p value 0.06) showed trend as predictors of ICrH expansion. ICrH expansion dichotomized by ≥6 mls or <6 mls as dependent variable, identified similar predictors of ICrH expansion.

Conclusions: Shorter time from onset of symptoms to CT, lower GCS score and larger hematoma volumes at presentation increased the probability of ICrH expansion in FXa-associated ICrH treated with andexanet. These findings can inform the eligibility criteria of clinical trials targeting hemostatic efficacy in patients with FXa-associated ICrH.

Association Between Duration of Transient Neurological Events and Diffusion-Weighted Brain Lesions

Background The relationship between duration of transient neurological events and presence of diffusion-weighted lesions by symptom type is unclear. Methods and Results This was a substudy of SpecTRA (Spectrometry for Transient Ischemic Attack Rapid Assessment), a multicenter prospective cohort of patients with minor ischemic cerebrovascular events or stroke mimics at academic emergency departments in Canada. For this study we included patients with resolved symptoms and determined the presence of diffusion-weighted imaging (DWI) lesion on magnetic resonance imaging within 7 days. Using logistic regression, we evaluated the association between symptom duration and DWI lesion, assessing for interaction with symptom type (focal only versus nonfocal/mixed), and adjusting for age, sex, education, comorbidities, and systolic blood pressure. Of 658 patients included, a DWI lesion was present in 232 (35.1%). There was a significant interaction between symptom duration and symptom type. For those with focal-only symptoms, there was a continuous increase in DWI probability up to 24 hours in duration (ranging from ≈40% to 80% probability). In stratified analyses, the increase in probability of DWI lesion with increased duration of focal symptoms was seen in women but not men. For those with nonfocal or mixed symptoms, predicted probability of DWI lesion was ≈35% and was greater in men, but did not increase with longer duration. Conclusions Increased duration of neurological deficits is associated with greater probability of DWI lesion in those with focal symptoms only. For individuals with nonfocal or mixed symptoms, about one-third had DWI lesions, but the probability did not increase with duration. These results may be important to improve risk stratification of transient neurological events.

Cost-Effectiveness of Endovascular Treatment in Large Vessel Occlusion Stroke With Mild Prestroke Disability: Results From the HERMES Collaboration

BACKGROUND

The clinical and economic benefit of endovascular treatment (EVT) in addition to best medical management in patients with stroke with mild preexisting symptoms/disability is not well studied. We aimed to investigate cost-effectiveness of EVT in patients with large vessel occlusion and mild prestroke symptoms/disability, defined as a modified Rankin Scale score of 1 or 2.

METHODS

Data are from the HERMES collaboration (Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke Trials), which pooled patient-level data from 7 large, randomized EVT trials. We used a decision model consisting of a short-run model to analyze costs and functional outcomes within 90 days after the index stroke and a long-run Markov state transition model (cycle length of 12 months) to estimate expected lifetime costs and outcomes from a health care and a societal perspective. Incremental cost-effectiveness ratio and net monetary benefits were calculated, and a probabilistic sensitivity analysis was performed.

RESULTS

EVT in addition to best medical management resulted in lifetime cost savings of $2821 (health care perspective) or $5378 (societal perspective) and an increment of 1.27 quality-adjusted life years compared with best medical management alone, indicating dominance of additional EVT as a treatment strategy. The net monetary benefits were higher for EVT in addition to best medical management compared with best medical management alone both at the higher (100 000$/quality-adjusted life years) and lower (50 000$/quality-adjusted life years) willingness to pay thresholds. Probabilistic sensitivity analysis showed decreased costs and an increase in quality-adjusted life years for additional EVT compared with best medical management only.

CONCLUSIONS

From a health-economic standpoint, EVT in addition to best medical management should be the preferred strategy in patients with acute ischemic stroke with large vessel occlusion and mild prestroke symptoms/disability.

Quantification of clot spatial heterogeneity and its impact on thrombectomy

BACKGROUND

Compositional and structural features of retrieved clots by thrombectomy can provide insight into improving the endovascular treatment of ischemic stroke. Currently, histological analysis is limited to quantification of compositions and qualitative description of the clot structure. We hypothesized that heterogeneous clots would be prone to poorer recanalization rates and performed a quantitative analysis to test this hypothesis.

METHODS

We collected and did histology on clots retrieved by mechanical thrombectomy from 157 stroke cases (107 achieved first-pass effect (FPE) and 50 did not). Using an in-house algorithm, the scanned images were divided into grids (with sizes of 0.2, 0.3, 0.4, 0.5, and 0.6 mm) and the extent of non-uniformity of RBC distribution was computed using the proposed spatial heterogeneity index (SHI). Finally, we validated the clinical significance of clot heterogeneity using the Mann-Whitney test and an artificial neural network (ANN) model.

RESULTS

For cases with FPE, SHI values were smaller (0.033 vs 0.039 for grid size of 0.4 mm, P=0.028) compared with those without. In comparison, the clot composition was not statistically different between those two groups. From the ANN model, clot heterogeneity was the most important factor, followed by fibrin content, thrombectomy techniques, red blood cell content, clot area, platelet content, etiology, and admission of intravenous tissue plasminogen activator (IV-tPA). No statistical difference of clot heterogeneity was found for different etiologies, thrombectomy techniques, and IV-tPA administration.

CONCLUSIONS

Clot heterogeneity can affect the clot response to thrombectomy devices and is associated with lower FPE. SHI can be a useful metric to quantify clot heterogeneity.

Significance of Baseline Ischemic Core Volume on Stroke Outcome After Endovascular Therapy in Patients Age ≥75 Years: A Pooled Analysis of Individual Patient Data From 7 Trials

Background:

Age and infarct volume are strong predictors of outcome in patients with ischemic stroke who underwent endovascular therapy (EVT). We aimed to investigate the impact of ischemic core volume (ICV) on stroke outcome after EVT in elderly.

Methods:

Using the HERMES (Highly Effective Reperfusion Using Multiple Endovascular Devices) collaboration, a patient-level meta-analysis of 7 randomized trials in which patients were enrolled from December 2010 to April 2015) dataset, we categorized patients into those aged <75 and ≥75 years. ICV was calculated on computed tomography perfusion or magnetic resonance diffusion-weighted imaging. The association between ICV and the benefit of EVT over best medical treatment on outcome (modified Rankin Scale [mRS] at 90 days) and an ICV threshold for high likelihood (≥90%) of very poor outcome (mRS score ≥5) after EVT were investigated.

Results:

A total of 899 patients who had baseline ICV data, 247 patients aged ≥75 years, of which 118 were randomized in the EVT arm. Patients aged ≥75 years required smaller ICV to achieve mRS score ≤3 than those aged <75 years in the EVT arm (median 10.7 mL versus 23.9 mL, P <0.001). In patients aged ≥75 years, modeling of outcome in both treatment arms revealed potential loss of effect for EVT at ICV of ≥50 mL or ≥85 mL for achieving mRS score ≤3 or ≤4, respectively. Treatment effect of EVT was significant in ICV <50 mL for mRS ≤3 (odds ratio 2.38, 95% confidence interval 1.35–4.22). ICV ≥132 mL was a threshold for high likelihood of very poor outcome after EVT. However, EVT still predicted at least 30% rate of mRS ≤3 at 150 mL ICV if near-complete or complete reperfusion was achieved.

Conclusions:

Baseline ICV has an impact on stroke outcome after EVT in the elderly, but elderly patients with large ICV may still benefit from EVT if near-complete or complete reperfusion is achieved. Young patients seem to benefit from EVT regardless of ICV status.

Factor XIa inhibition with asundexian after acute non-cardioembolic ischaemic stroke (PACIFIC-Stroke): an international, randomised, double-blind, placebo-controlled, phase 2b trial

BACKGROUND

Asundexian (Bayer AG, Leverkusen, Germany), an oral small molecule factor XIa (FXIa) inhibitor, might prevent thrombosis without increasing bleeding. Asundexian's effect for secondary prevention of recurrent stroke is unknown.

METHODS

In this randomised, double-blind, placebo-controlled, phase 2b dose-finding trial (PACIFIC-Stroke), patients with acute (within 48 h) non-cardioembolic ischaemic stroke were recruited from 196 hospitals in 23 countries. Patients were eligible if they were aged 45 years or older, to be treated with antiplatelet therapy, and able to have a baseline MRI (either before or within 72 h of randomisation). Eligible participants were randomly assigned (1:1:1:1), using an interactive web-based response system and stratified according to anticipated antiplatelet therapy (single vs dual), to once daily oral asundexian (BAY 2433334) 10 mg, 20 mg, or 50 mg, or placebo in addition to usual antiplatelet therapy, and were followed up during treatment for 26-52 weeks. Brain MRIs were obtained at study entry and at 26 weeks or as soon as possible after treatment discontinuation. The primary efficacy outcome was the dose-response effect on the composite of incident MRI-detected covert brain infarcts and recurrent symptomatic ischaemic stroke at or before 26 weeks after randomisation. The primary safety outcome was major or clinically relevant non-major bleeding as defined by International Society on Thrombosis and Haemostasis criteria. The efficacy outcome was assessed in all participants assigned to treatment, and the safety outcome was assessed in all participants who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov, NCT04304508, and is now complete.

FINDINGS

Between June 15, 2020, and July 22, 2021, 1880 patients were screened and 1808 participants were randomly assigned to asundexian 10 mg (n=455), 20 mg (n=450), or 50 mg (n=447), or placebo (n=456). Mean age was 67 years (SD 10) and 615 (34%) participants were women, 1193 (66%) were men, 1505 (83%) were White, and 268 (15%) were Asian. The mean time from index stroke to randomisation was 36 h (SD 10) and median baseline National Institutes of Health Stroke Scale score was 2·0 (IQR 1·0-4·0). 783 (43%) participants received dual antiplatelet treatment for a mean duration of 70·1 days (SD 113·4) after randomisation. At 26 weeks, the primary efficacy outcome was observed in 87 (19%) of 456 participants in the placebo group versus 86 (19%) of 455 in the asundexian 10 mg group (crude incidence ratio 0·99 [90% CI 0·79-1·24]), 99 (22%) of 450 in the asundexian 20 mg group (1·15 [0·93-1·43]), and 90 (20%) of 447 in the asundexian 50 mg group (1·06 [0·85-1·32]; t statistic -0·68; p=0·80). The primary safety outcome was observed in 11 (2%) of 452 participants in the placebo group versus 19 (4%) of 445 in the asundexian 10 mg group, 14 (3%) of 446 in the asundexian 20 mg group, and 19 (4%) of 443 in the asundexian 50 mg group (all asundexian doses pooled vs placebo hazard ratio 1·57 [90% CI 0·91-2·71]).

INTERPRETATION

In this phase 2b trial, FXIa inhibition with asundexian did not reduce the composite of covert brain infarction or ischaemic stroke and did not increase the composite of major or clinically relevant non-major bleeding compared with placebo in patients with acute, non-cardioembolic ischaemic stroke.

FUNDING

Bayer AG.

Prediction of 90 day home time among patients with low baseline ASPECTS undergoing endovascular thrombectomy: results from Alberta's Provincial Stroke Registry (QuICR)

BACKGROUND

The benefit of endovascular thrombectomy (EVT) in stroke patients with a low baseline Alberta Stroke Program Early CT Score (ASPECTS, ≤5) is uncertain. We aim to use random forest regression modeling to predict 90 day home time in patients with low ASPECTS.

METHODS

We used the Quality Improvement and Clinical Research (QuICR) provincial stroke registry and administrative data from southern Alberta to identify patients who underwent EVT in our center from July 2015 to November 2020. Baseline ASPECTS on non-contrast CT and CT angiography data were scored by a two physician consensus. The primary outcome was the predicted 90 day home time (the number of nights a patient is back at their premorbid living situation without an increase in level of care within 90 days of the stroke) using random forests regression. Estimates were generated using 200 bootstrapped datasets. Covariate contribution to home time was determined using partial dependence plots.

RESULTS

Of 657 EVT patients, 85 (12.9%) had baseline ASPECTS ≤5 (mean age 70.9 years, 44.7% women, 93.9% good-moderate collaterals, 60% M1-middle cerebral artery occlusion). Using partial dependence estimates, mean predicted home times were similar in the low ASPECTS (44.3 days) versus higher ASPECTS (43.1) groups. Factors predicting lower 90 day home time in this population were diabetes mellitus (-8.8 days), hypertension (-5.7 days), and atrial fibrillation (-3.6 days). There was no meaningful difference in predicted 90 day home time by sex, baseline National Institutes of Health Stroke Severity Scale score, occlusion site, tandem lesion, collateral grade or thrombolysis.

CONCLUSIONS

Patients with low ASPECTS who are selected for EVT using demographic and clinical profiles similar to higher ASPECTS patients achieved comparable outcomes.

Prediction of 90 day home time among patients with low baseline ASPECTS undergoing endovascular thrombectomy: results from Alberta's Provincial Stroke Registry (QuICR)

BACKGROUND

The benefit of endovascular thrombectomy (EVT) in stroke patients with a low baseline Alberta Stroke Program Early CT Score (ASPECTS, ≤5) is uncertain. We aim to use random forest regression modeling to predict 90 day home time in patients with low ASPECTS.

METHODS

We used the Quality Improvement and Clinical Research (QuICR) provincial stroke registry and administrative data from southern Alberta to identify patients who underwent EVT in our center from July 2015 to November 2020. Baseline ASPECTS on non-contrast CT and CT angiography data were scored by a two physician consensus. The primary outcome was the predicted 90 day home time (the number of nights a patient is back at their premorbid living situation without an increase in level of care within 90 days of the stroke) using random forests regression. Estimates were generated using 200 bootstrapped datasets. Covariate contribution to home time was determined using partial dependence plots.

RESULTS

Of 657 EVT patients, 85 (12.9%) had baseline ASPECTS ≤5 (mean age 70.9 years, 44.7% women, 93.9% good-moderate collaterals, 60% M1-middle cerebral artery occlusion). Using partial dependence estimates, mean predicted home times were similar in the low ASPECTS (44.3 days) versus higher ASPECTS (43.1) groups. Factors predicting lower 90 day home time in this population were diabetes mellitus (-8.8 days), hypertension (-5.7 days), and atrial fibrillation (-3.6 days). There was no meaningful difference in predicted 90 day home time by sex, baseline National Institutes of Health Stroke Severity Scale score, occlusion site, tandem lesion, collateral grade or thrombolysis.

CONCLUSIONS

Patients with low ASPECTS who are selected for EVT using demographic and clinical profiles similar to higher ASPECTS patients achieved comparable outcomes.

Intravenous tenecteplase compared with alteplase for acute ischaemic stroke in Canada (AcT): a pragmatic, multicentre, open-label, registry-linked, randomised, controlled, non-inferiority trial

BACKGROUND

Intravenous thrombolysis with alteplase bolus followed by infusion is a global standard of care for patients with acute ischaemic stroke. We aimed to determine whether tenecteplase given as a single bolus might increase reperfusion compared with this standard of care.

METHODS

In this multicentre, open-label, parallel-group, registry-linked, randomised, controlled trial (AcT), patients were enrolled from 22 primary and comprehensive stroke centres across Canada. Patients were eligible for inclusion if they were aged 18 years or older, with a diagnosis of ischaemic stroke causing disabling neurological deficit, presenting within 4·5 h of symptom onset, and eligible for thrombolysis per Canadian guidelines. Eligible patients were randomly assigned (1:1), using a previously validated minimal sufficient balance algorithm to balance allocation by site and a secure real-time web-based server, to either intravenous tenecteplase (0·25 mg/kg to a maximum of 25 mg) or alteplase (0·9 mg/kg to a maximum of 90mg; 0·09 mg/kg as a bolus and then a 60 min infusion of the remaining 0·81 mg/kg). The primary outcome was the proportion of patients who had a modified Rankin Scale (mRS) score of 0-1 at 90-120 days after treatment, assessed via blinded review in the intention-to-treat (ITT) population (ie, all patients randomly assigned to treatment who did not withdraw consent). Non-inferiority was met if the lower 95% CI of the difference in the proportion of patients who met the primary outcome between the tenecteplase and alteplase groups was more than -5%. Safety was assessed in all patients who received any of either thrombolytic agent and who were reported as treated. The trial is registered with ClinicalTrials.gov, NCT03889249, and is closed to accrual.

FINDINGS

Between Dec 10, 2019, and Jan 25, 2022, 1600 patients were enrolled and randomly assigned to tenecteplase (n=816) or alteplase (n=784), of whom 1577 were included in the ITT population (n=806 tenecteplase; n=771 alteplase). The median age was 74 years (IQR 63-83), 755 (47·9%) of 1577 patients were female and 822 (52·1%) were male. As of data cutoff (Jan 21, 2022), 296 (36·9%) of 802 patients in the tenecteplase group and 266 (34·8%) of 765 in the alteplase group had an mRS score of 0-1 at 90-120 days (unadjusted risk difference 2·1% [95% CI - 2·6 to 6·9], meeting the prespecified non-inferiority threshold). In safety analyses, 27 (3·4%) of 800 patients in the tenecteplase group and 24 (3·2%) of 763 in the alteplase group had 24 h symptomatic intracerebral haemorrhage and 122 (15·3%) of 796 and 117 (15·4%) of 763 died within 90 days of starting treatment INTERPRETATION: Intravenous tenecteplase (0·25 mg/kg) is a reasonable alternative to alteplase for all patients presenting with acute ischaemic stroke who meet standard criteria for thrombolysis.

FUNDING

Canadian Institutes of Health Research, Alberta Strategy for Patient Oriented Research Support Unit.

Functional Outcomes of Patients ≥85 Years With Acute Ischemic Stroke Following EVT: A HERMES Substudy

BACKGROUND

Observational studies have shown endovascular treatment (EVT) for acute ischemic stroke to be effective in the elderly, despite resulting in poorer outcomes and higher rates of mortality compared with younger patients. Randomized data on the effect of advanced age on outcomes following EVT are, however, lacking. Our aim was to assess the EVT effect for ischemic stroke in patients aged ≥85 years and the influence of age on outcome in a large, randomized trial dataset.

METHODS

Data were from the HERMES (Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke Trials) collaboration, a meta-analysis of 7 randomized trials published between January 1, 2010, and May 31, 2017, that tested the efficacy of EVT. A possible multiplicative interaction effect of age on the relationship between treatment and outcome was investigated. Ordinal logistic regression tested the association between EVT and 90-day functional outcome (modified Rankin Scale, primary outcome) in patients ≥85 years. Multivariable binary logistic regression was performed to compare primary and secondary outcomes (modified Rankin Scale score of 0-2/5-6) of patients ≥85 years versus those <85 years.

RESULTS

We included 1764 patients in the analysis, of whom 77 (4.4%) were ≥85 years old. A significant interaction of age and treatment on poor outcome (modified Rankin Scale score of 5-6, P=0.020) and mortality (P=0.031) was observed, with older adults having worse functional outcomes at 90 days compared with younger patients (adjusted common odds ratio, 0.20 [95% CI, 0.13-0.33]). However, a benefit of EVT was observed in the ≥85-year-old patient subgroup (common odds ratio, 4.20 [95% CI, 1.56-11.32]). Age ≥85 years was not significantly associated with differing rates of symptomatic intracerebral hemorrhage or reperfusion (adjusted odds ratio, 1.92 [95% CI, 0.71-5.15] and adjusted odds ratio, 0.91 [95% CI, 0.40-2.06], respectively).

CONCLUSIONS

Patients ≥85 years old with independent premorbid function more often achieve good functional outcomes and have lower rates of mortality when treated with EVT compared with conservative management, with an observed treatment effect modification of age on outcome. EVT should therefore not be withheld in this subgroup.

Correlation of von Willebrand factor and platelets with acute ischemic stroke etiology and revascularization outcome: an immunohistochemical study

BACKGROUND

Platelets and von Willebrand factor (vWF) are key components of acute ischemic stroke (AIS) emboli. We aimed to investigate the CD42b (platelets)/vWF expression, its association with stroke etiology and the impact these components may have on the clinical/procedural parameters.

METHODS

CD42b/vWF immunostaining was performed on 288 emboli collected as part of the multicenter STRIP Registry. CD42b/VWF expression and distribution were evaluated. Student's t-test and χ² test were performed as appropriate.

RESULTS

The mean CD42b and VWF content in clots was 44.3% and 21.9%, respectively. There was a positive correlation between platelets and vWF (r=0.64, p<0.001**). We found a significantly higher vWF level in the other determined etiology (p=0.016*) and cryptogenic (p=0.049*) groups compared with cardioembolic etiology. No significant difference in CD42b content was found across the etiology subtypes. CD42b/vWF patterns were significantly associated with stroke etiology (p=0.006*). The peripheral pattern was predominant in atherosclerotic clots (36.4%) while the clustering (patchy) pattern was significantly associated with cardioembolic and cryptogenic origin (66.7% and 49.8%, respectively). The clots corresponding to other determined etiology showed mainly a diffuse pattern (28.1%). Two types of platelets were distinguished within the CD42b-positive clusters in all emboli: vWF-positive platelets were observed at the center, surrounded by vWF-negative platelets. Thrombolysis correlated with a high platelet content (p=0.03*). vWF-poor and peripheral CD42b/vWF pattern correlated with first pass effect (p=0.03* and p=0.04*, respectively).

CONCLUSIONS

The vWF level and CD42b/vWF distribution pattern in emboli were correlated with AIS etiology and revascularization outcome. Platelet content was associated with response to thrombolysis.

Correlation Between Computed Tomography-Based Tissue Net Water Uptake and Volumetric Measures of Cerebral Edema After Reperfusion Therapy

BACKGROUND

Cerebral edema after large hemispheric infarction is associated with poor functional outcome and mortality. Net water uptake (NWU) quantifies the degree of hypoattenuation on unenhanced-computed tomography (CT) and is increasingly used to measure cerebral edema in stroke research. Hemorrhagic transformation and parenchymal contrast staining after thrombectomy may confound NWU measurements. We investigated the correlation of NWU measured postthrombectomy with volumetric markers of cerebral edema and association with functional outcomes.

METHODS

In a pooled individual patient level analysis of patients presenting with anterior circulation large hemispheric infarction (core 80-300 mL or Alberta Stroke Program Early CT Score ≤5) in the HERMES (Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke trials) data set, cerebral edema was defined as the volumetric expansion of the ischemic hemisphere expressed as a ratio to the contralateral hemisphere(rHV). NWU and midline-shift were compared with rHV as the reference standard on 24-hour follow-up CT, adjusted for hemorrhagic transformation and the use of thrombectomy. Association between edema markers and day 90 functional outcomes (modified Rankin Scale) was assessed using ordinal logistic regression.

RESULTS

Overall (n=144), there was no correlation between NWU and rHV (r_s=0.055, P=0.51). In sub-group analyses, a weak correlation between NWU with rHV was observed after excluding patients with any degree of hemorrhagic transformation (r_s=0.211, P=0.015), which further improved after excluding thrombectomy patients (r_s=0.453, P=0.001). Midline-shift correlated strongly with rHV in all sub-group analyses (r_s>0.753, P=0.001). Functional outcome at 90 days was negatively associated with rHV (adjusted common odds ratio, 0.46 [95% CI, 0.32-0.65]; P<0.001) and midline-shift (adjusted common odds ratio, 0.85 [95% CI, 0.78-0.92]; P<0.001) but not NWU (adjusted common odds ratio, 1.00 [95% CI, 0.97-1.03]; P=0.84), adjusted for age, baseline National Institutes of Health Stroke Scale, and thrombectomy. Prognostic performance of NWU improved after excluding patients with hemorrhagic transformation and thrombectomy (adjusted odds ratio, 0.90 [95% CI, 0.80-1.02]; P=0.10).

CONCLUSIONS

NWU correlated poorly with conventional markers of cerebral edema and was not associated with clinical outcome in the presence of hemorrhagic transformation and thrombectomy. Measuring NWU postthrombectomy requires validation before implementation into clinical research. At present, the use of NWU should be limited to baseline CT, or follow-up CT only in patients without hemorrhagic transformation or treatment with thrombectomy.

Association of Iatrogenic Infarcts With Clinical and Cognitive Outcomes in the Evaluating Neuroprotection in Aneurysm Coiling Therapy Trial

BACKGROUND AND OBJECTIVES

Small iatrogenic brain infarcts are often seen on diffusion-weighted MRI (DWI) following surgical or endovascular procedures, but there are few data on their clinical effects. We examined the association of iatrogenic infarcts with outcomes in the ENACT (Evaluating Neuroprotection in Aneurysm Coiling Therapy) randomized controlled trial of nerinetide in patients undergoing endovascular repair of intracranial aneurysms.

METHODS

In this post hoc analysis, we used multivariable models to evaluate the association of the presence and number of iatrogenic infarcts on DWI with neurologic impairment (NIH Stroke Scale [NIHSS]), functional status (modified Rankin Scale [mRS]), and cognitive and neuropsychiatric outcomes (30-minute test battery) at 1-4 days and 30 days postprocedure. We also related infarct number to a z score-derived composite outcome score using quantile regression.

RESULTS

Among 184 patients (median age 56 years [interquartile range (IQR) 50-64]), 124 (67.4%) had postprocedural DWI lesions (median 4, IQR 2-10.5). Nerinetide treatment was associated with fewer iatrogenic infarcts but no overall significant clinical treatment effects. Patients with infarcts had lower Mini-Mental State Examination (MMSE) scores at 2-4 days (median 28 vs 29, adjusted coefficient [acoef] -1.11, 95% CI -1.88 to -0.34, p = 0.005). Higher lesion counts were associated with worse day 1 NIHSS (adjusted odds ratio for NIHSS ≥1: 1.07, 1.02-1.12, p = 0.009), day 2-4 mRS (adjusted common odds ratio [acOR] 1.05, 1.01-1.09, p = 0.005), and day 2-4 MMSE (acoef -0.07, -0.13 to -0.003, p = 0.040) scores. At 30 days, infarct number remained associated with worse mRS (acOR 1.04, 1.01-1.07, p = 0.016) and Hopkins Verbal Learning Test (HVLT) delayed recall scores (acoef -0.21, -0.39 to -0.03, p = 0.020). Patients with infarcts trended towards lower 30-day Digit Symbol Substitution Test (DSST) scores (acoef -3.73, -7.36 to -0.10, p = 0.044). Higher lesion count was associated with worse composite outcome scores at both 1-4 days and 30 days (30-day acoef -0.12, 95% CI -0.21 to -0.03, p = 0.008). Among those with infarcts, day 1 NIHSS and day 2-4 mRS correlated with 30-day NIHSS, DSST, HVLT, and mRS scores, whereas day 2-4 MMSE correlated with 30-day NIHSS and DSST scores (Spearman ρ 0.47, p = 0.001).

DISCUSSION

Iatrogenic brain infarcts were associated with subtle differences in postprocedural (1-4 days) and 30-day outcomes on different measures in this middle-aged cohort, with earlier dysfunction correlating with later differences.

TRIAL REGISTRATION INFORMATION

Clinical trials registration NCT00728182.

Thrombectomy With and Without Computed Tomography Perfusion Imaging in the Early Time Window: A Pooled Analysis of Patient-Level Data

BACKGROUND

The optimal imaging paradigm for endovascular thrombectomy (EVT) patient selection in early time window (0-6 hours) treated acute ischemic stroke patients remains uncertain. We aimed to compare post-EVT outcomes between patients who underwent prerandomization basic (noncontrast computed tomography [CT], CT angiography only) versus additional advanced imaging (computed tomography perfusion [CTP] imaging) and to determine the association of performance of prerandomization CTP imaging with clinical outcomes.

METHODS

The HERMES collaboration (Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke Trials) pooled patient-level data from randomized controlled trials comparing EVT with usual care for acute ischemic stroke due to anterior circulation large vessel occlusion. Good functional outcome, defined as modified Rankin Scale score 0 to 2 at 90 days, was compared between randomized patients with and without CTP baseline imaging. Univariable and multivariable binary logistic regression analysis was performed to determine the association of baseline CTP imaging and good functional outcome.

RESULTS

We analyzed 1348 patients 610 (45.3%) of whom underwent CTP prerandomization. The benefit of EVT compared with best medical management was maintained irrespective of the baseline imaging paradigm (90-day modified Rankin Scale score 0-2 in EVT versus control patients: with CTP: 46.0% (137/298) versus 28.9% (88/305), without CTP: 44.1% (162/367) versus 27.3% (100/366). Performance of CTP baseline imaging compared with baseline noncontrast CT and CT angiography only yielded similar rates of good outcome (odds ratio, 1.05 [95% CI, 0.82-1.33], adjusted odds ratio, 1.04, [95% CI, 0.80-1.35]).

CONCLUSIONS

Rates of good functional outcome were similar among patients in whom CTP was or was not performed, and EVT treatment effect in the 0- to 6-hour time window was similar in patients with and without baseline CTP imaging.

Histological composition of retrieved emboli in acute ischemic stroke is independent of pre-thrombectomy alteplase use

BACKGROUND AND PURPOSE

Given recent evidence suggesting the clot composition may be associated with revascularization outcomes and stroke etiology, clot composition research has been a topic of growing interest. It is currently unclear what effect, if any, pre-thrombectomy thrombolysis has on clot composition. Understanding this association is important as it is a potential confounding variable in clot composition research. We retrospectively evaluated the composition of retrieved clots from ischemic stroke patients who did and did not receive pre-treatment tPA to study the effect of tPA on clot composition.

MATERIALS AND METHODS

Consecutive patients enrolled in the Stroke Thromboembolism Registry of Imaging and Pathology (STRIP) were included in this study. All patients underwent mechanical thrombectomy and retrieved clots were sent to a central core lab for processing. Histological analysis was performed using Martius Scarlett Blue (MSB) staining and area of the clot was also measured on the gross photos. Student's t test was used for continuous variables and chi-squared test for categorical variables.

RESULTS

A total of 1430 patients were included in this study. Mean age was 68.4±13.5 years. Overall rate of TICI 2c/3 was 67%. A total of 517 patients received tPA (36%) and 913 patients did not (64%). Mean RBC density for the tPA group was 42.97±22.62% compared to 42.80±23.18% for the non-tPA group (P=0.89). Mean WBC density for the tPA group was 3.74±2.60% compared to 3.42±2.21% for the non-tPA group (P=0.012). Mean fibrin density for the tPA group was 26.52±15.81% compared to 26.53±15.34% for the non-tPA group (P=0.98). Mean platelet density for the tPA group was 26.22±18.60% compared to 26.55±19.47% for the non-tPA group (P=0.75). tPA group also had significantly smaller clot area compared to non-tPA group.

CONCLUSIONS

Our study 1430 retrieved emboli and ischemic stroke patients shows no interaction between tPA administration and clot composition. These findings suggest that tPA does not result in any histological changes in clot composition.

Abstract WMP51: Outcome Prediction In Late-Window Endovascular Treatment - Application Of MR PREDICTS To Patients Treated Beyond 6 Hours

Introduction: Outcome prediction tools for large vessel occlusion (LVO) stroke patients receiving endovascular treatment (EVT) focus on patients treated within 6h from onset. We aimed to apply a validated tool to EVT-treated patients in the late window (beyond 6h from onset) and to investigate any outcome differences according to the imaging paradigm used for selection.

Methods: MR PREDICTS is a prediction tool of the effect and benefit of EVT on functional outcome based on MR CLEAN and HERMES data sets. We applied the algorithm to patients treated with late-window EVT from three multicenter international trials (ESCAPE, ESCAPE-NA1, and ProVe-IT). We assessed the model performance by calculating its discrimination and calibration for the overall patient sample and for the subset of patients who underwent CTP.

Results: We included 152 patients: 93 (61.2%) from the control arm of ESCAPE-NA1, 35 (23.0%) from ProVe-IT, and 24 (15.8%) from ESCAPE. Median age was 68.0 years (IQR: 58.0 - 77.2), median baseline NIHSS was 16 (IQR: 12 - 20) and 72.4% had M1-occlusions. Median time from onset to groin puncture was 592min (IQR: 496 - 666). Good functional outcome (mRS 0-2) at 3 months was achieved in 72/152 patients (47.4%). The averaged predicted probability of mRS 0-2 was 47.6%. In the CTP-subgroup 44/94 patients (46.8%) achieved mRS 0-2, the averaged predicted probability of mRS 0-2 was 46.5%. Evaluation of model performance resulted in a reasonable discriminative ability (Harrel’s c-statistic: overall 0.75, 95%CI 0.67 - 0.82, CTP-subgroup: 0.73, 95%CI 0.62 - 0.82, figure 1).

Conclusions: The outcome-prediction model performed reasonably well when applied to EVT patients in the late time window. Our data supports the use of available prediction tools in patients treated beyond 6h of symptom onset until specific models are developed for late-window patients.

Abstract TP186: Heterogeneity Of Endovascular Treatment Effect: A Comparison Of Subgroup Identification Methods In Acute Stroke Trials

Background: Trials’ data are increasingly re-analyzed to identify treatment effect heterogeneity: that is, subgroups of patients who have either enhanced or adverse effects in a trial. This study investigates the robustness of subgroup identification methods in an acute stroke trial.

Methods and Analysis: The Model-based recursive partitioning (MOB), Stochastic Subgroup Identification based on Differential Effects Search (Stochastic SIDEScreen), and Virtual Twin (VT) methods would be used to detect heterogeneity in Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion with Emphasis on Minimizing CT to Recanalization Times (ESCAPE) trial.

Results: In the ESCAPE trial, patients in the intervention group had a higher rate of functional independence (90-day mRS 0-2) than those in the control group (OR=2.6; p<0.001, and 95% CI=1.7–3.8). The three methods identified patients with differential treatment effects. The MOB identified 2-terminal subgroups, with the NIHSS > 11 group showing a significant treatment effect (OR=3.67; p<0.001 and 95% CI=2.11–6.40), while the subgroup of with a maximum NIHSS score of 11 did not (OR=1.63; p=0.463 and 95% CI=0.44–6.05). The stochastic SIDEScreen identified 4-terminal subgroups, but the group of patients with NIHSS greater than 9 and older than 54 years had a significant treatment effect (OR=4.92; p<0.001, and 95% CI= 2.66–9.10). Other three subgroups, like patients with a maximum NIHSS score of 9 and older than 54 years (OR=2.17, p=0.34, and 95% CI=0.44–10.65), did not have a significant treatment effect. VT identified 6-terminal subgroups; the subgroup consisting of patients older than 56 years and NIHSS > 11 had significant treat effect (OR=5.11; p<0.001 and 95% CI=2.68–9.73). As other renaming 4 subgroups, the subgroup consisting of younger patients and with a maximum NIHSS score of 11 did not show a treatment effect (OR=1.60, p=0.64, and 95% CI=0.39–6.30).

Conclusion: Data-driven subgroup identification methods provide insight into the heterogeneity of treatment effects in acute stroke trials. Information about the identified subgroups might inform the development of clinical practice guidelines for acute stroke management.