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.

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.

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.

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.

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.

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.