Global impact of COVID-19 on stroke care

Background

The COVID-19 pandemic led to profound changes in the organization of health care systems worldwide.

Aims

We sought to measure the global impact of the COVID-19 pandemic on the volumes for mechanical thrombectomy, stroke, and intracranial hemorrhage hospitalizations over a three-month period at the height of the pandemic (1 March–31 May 2020) compared with two control three-month periods (immediately preceding and one year prior).

Methods

Retrospective, observational, international study, across 6 continents, 40 countries, and 187 comprehensive stroke centers. The diagnoses were identified by their ICD-10 codes and/or classifications in stroke databases at participating centers.

Results

The hospitalization volumes for any stroke, intracranial hemorrhage, and mechanical thrombectomy were 26,699, 4002, and 5191 in the three months immediately before versus 21,576, 3540, and 4533 during the first three pandemic months, representing declines of 19.2% (95%CI, −19.7 to −18.7), 11.5% (95%CI, −12.6 to −10.6), and 12.7% (95%CI, −13.6 to −11.8), respectively. The decreases were noted across centers with high, mid, and low COVID-19 hospitalization burden, and also across high, mid, and low volume stroke/mechanical thrombectomy centers. High-volume COVID-19 centers (−20.5%) had greater declines in mechanical thrombectomy volumes than mid- (−10.1%) and low-volume (−8.7%) centers (p < 0.0001). There was a 1.5% stroke rate across 54,366 COVID-19 hospitalizations. SARS-CoV-2 infection was noted in 3.9% (784/20,250) of all stroke admissions.

Conclusion

The COVID-19 pandemic was associated with a global decline in the volume of overall stroke hospitalizations, mechanical thrombectomy procedures, and intracranial hemorrhage admission volumes. Despite geographic variations, these volume reductions were observed regardless of COVID-19 hospitalization burden and pre-pandemic stroke/mechanical thrombectomy volumes.

Association between clot composition and stroke origin in mechanical thrombectomy patients: analysis of the Stroke Thromboembolism Registry of Imaging and Pathology

BACKGROUND

We retrospectively evaluated the composition of retrieved clots from ischemic stroke patients to study the association between histological composition and stroke etiology 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 scarlet blue (MSB) staining, and quantification for red blood cells (RBCs), white blood cells (WBCs), fibrin and platelets was performed using Orbit Image Software. A Wilcoxon test was used for continuous variables and χ² test for categorical variables.

RESULTS

1350 patients were included in this study. The overall rate of Thrombolysis In Cerebral Infarction (TICI) 2c/3 was 68%. 501 patients received tissue plasminogen activator (tPA) (37%). 267 patients (20%) had a large artery atherosclerosis (LAA) source, 662 (49%) a cardioembolic (CE) source, 301 (22%) were cryptogenic, and the remainder had other identifiable sources including hypercoagulable state or dissection. LAA thrombi had a higher mean RBC density (46±23% vs 42±22%, p=0.01) and a lower platelet density (24±18% vs 27±18%, p=0.03) than CE thrombi. Clots from dissection patients had the highest mean RBC density (50±24%) while clots from patients with a hypercoagulable state had the lowest mean RBC density (26±21%).

CONCLUSIONS

Our study found statistically significant but clinically insignificant differences between clots of CE and LAA etiologies. Future studies should emphasize molecular, proteomic and immunohistochemical characteristics to determine links between clot composition and etiology.

Health-Related Quality of Life Among Patients With Acute Ischemic Stroke and Large Vessel Occlusion in the ESCAPE Trial

[Figure: see text].

Abstract P498: Quality of Reperfusion - Association of Stent Retriever Characteristics and Successful Reperfusion in ESCAPE-NA1 Dataset

Background: We evaluated technical aspects of stent retriever use and its relation to reperfusion in ESCAPE NA1 trial.

Methods: ESCAPE-NA1 was a multicenter, international randomized trial assessing the efficacy of nerinetide in ischemic stroke patients who underwent EVT within 12h from onset. The following stent retriever characteristics were evaluated: stent retriever length, diameter, thrombus position in relation to stent retriever - proximal, middle or distal third, bypass effect during stent retriever deployment (Figure 1), and stent retriever placement in the anterior or posterior MCA trunk (in M1 occlusions). Primary outcome was reperfusion grade and the unit of analysis was stent retriever attempt.

Results: Data from 1062 patients were evaluated. Angiographic data for up to three passes were analyzed as only 8.9% of patients required >3 passes. Stent retriever was used in 1241 passes in 808 patients. The occlusion sites were terminal ICA (14.9%), M1 MCA (58.7%), M2 MCA (23.7%), other (2.1%). A successful reperfusion attempt (mTICI 2b-3) was associated with the presence of bypass effect (OR 1.7; 95%CI 1.07-2.72), and positioning of stent retriever so the thrombus was in the proximal and middle third of stent retriever (OR 2.06; 95%CI 1.24-3.40 and OR 1.92; 95%CI 1.16-3.15, respectively). The position of the thrombus in the middle third of stent retriever was a significant predictor of bypass effect (OR 2.71; 95%CI 1.61-4.58). Stent retriever length, diameter, or choice of MCA trunk did not predict successful attempts, Table 1.

Conclusion: Bypass effect and positioning of stent retriever so the thrombus was in proximal 2/3rds are predictors of successful reperfusion attempts.

Abstract P524: Impact of Intra-Procedural Workflow and Time Metrics of Establishing Fast Reperfusion on Clinical Outcomes in the ESCAPE-NA1 Trial

Background: Time from imaging to establishing reperfusion is a major influencer of clinical outcomes and over the years thrombectomy techniques have evolved rapidly. This has led to improvements in achieving fast and complete reperfusion. We analyzed the impact of various intra-procedural techniques and tools on the speed of reperfusion and correlated procedural duration with probability of achieving good clinical outcomes.

Methods: We analyzed intra-procedural time metrics and examined factors leading to delays during EVT. The relationship between outcome (mRS Scale) and procedural time from arterial puncture to time of achieving mTICI 2b-3 First Reperfusion (FRE) was modeled using logistic regression.

Results: The various procedural time metrics are summarized in Figure 1. Every 10-minute increase in FRE time reduced the probability of achieving functional independence(90-day modified Rankin Scale 0-2) by 6.7% (P=0.021, adjusted). The medianFRE timewas 25min (IQR 17-39) and was significantly longer in patients with tandem occlusions(median 34min, p 0.0005). General anesthesia vs procedural sedation vs no sedation use did not significantly alter the FRE time (p = 0.1453). The use of BGC (54.2%) was nominally longer FRE (median 26min “IQR 18-38” vs 23ming, “IQR 16-38”; p 0.095)while the use of contact aspiration (n=213) vs retrievable stents (n=676) as the first approach was associated with a shorter FRE time (21min “IQR 14-35” vs 26 min “IQR18-40”, p =0.001).

Conclusions: Puncture to first reperfusion time is a significant predictor of clinical outcome in theESCAPE-NA1 trial. Various procedural and anatomical factors influence this timemetric.

Figure: Intra-Procedural workflow time metrics expressed in medians and 90th percentiles. The cumulative times are calculated for each major milestone in the procedure for upto three attempts. First reperfusion duration where TICI 2b was achieved is shown in comparison to other procedural time metrics.

Abstract P334: Multiphase Computed Tomography Angiography-Perfusion for Quantitative Measurement of Ischemic Volumes

Introduction: Proficiency required to execute CT perfusion (CTP) protocols is a limiting factor in its use in acute stroke. We propose to calculate perfusion parametric maps and measure ischemic volumes using readily available non-contrast CT (NCCT) and multiphase CT angiography (mCTA) images.

Materials and Methods: Twenty-five patients presenting with acute ischemic stroke were included in this study. Our proposed dynamic sequence (multiphase CT angiography-perfusion, mCTA-P) consisted of the NCCT as the pre-contrast baseline and three phases of mCTA, which corresponded to the peak arterial, peak venous, and late venous phases at 8 s intervals. CTP was acquired after mCTA and consisted of 22 dynamic images acquired over 60 s at 2.8 s intervals. A prototype model-based deconvolution algorithm (CT Perfusion 4D, GE Healthcare) was used to calculate cerebral blood flow (CBF) and Tmax maps for each series. Infarct was classified as voxels that satisfied both a time-dependent relative CBF threshold and Tmax > 8 s while penumbral voxels satisfied either threshold but not both.

Results: Median (interquartile range) 24-hour follow-up infarct volume was 18.6 (4.7 to 34.3) ml and median stroke onset-to-CTP time was 124.0 (70.5 to 201.5) min. Bland-Altman analysis revealed good agreement between CTP and mCTA-P volume measurements as mean differences (limits of agreement) were -1.0 (-14.9 to 12.9) ml for infarct and 8.4 (-42.4 to 59.1) ml for penumbra. Intraclass correlation (95% confidence interval, p < 0.05) between CTP and mCTA-P volumes were 0.72 (0.46 to 0.87) for infarct and 0.68 (0.41 to 0.85) for penumbra, indicating good to moderate reliability.

Conclusion: Quantitative perfusion can be estimated from NCCT and mCTA without introducing additional scan time, radiation dose, and contrast injections associated with CTP. Our technique allows assessments of early ischemic changes and collaterals to be augmented with quantitative perfusion measurements of ischemic volumes.

Abstract P550: Incidence, Predictors and Impact of Emboli in New Territory in Escape NA1 Trial

Introduction: Emboli in new territory (ENT) are known potential complication of endovascular thrombectomy. We explored their incidence and predictors in ESCAPE-NA-1 trial.

Methods: We included patients from the ESCAPE-NA1: a multicenter, international randomized study that assessed the efficacy of intravenous nerinetide in patients with acute ischemic stroke who underwent EVT within 12 hours from onset. All the imaging was reassessed, and ENT was defined as angiographic evidence of emboli in vascular territories other than the MCA, which was not present in the initial CT angiogram. We collected details of management and its influence on outcomes.

Results: We analyzed 1095 patients from the ESCAPE NA1. ENT occurred in 40 patients (3.6%, mean age 69.5 years, 50% females). There were no significant differences at baseline in groups with and without ENT. Most common ENT site was ACA (38,95%). Thrombolysis, use of balloon guide catheter, nerinetide treatment, and initial occlusion site did not predict ENT. Seven ENTs (17.5%) were pursued with endovascular therapy: retrievable stents in 6 patients and intra-arterial thrombolysis in 1 patient. Patients with ENT had longer total arterial puncture to first reperfusion times (65 vs 40.5 minutes, P<0.001), and a higher final median infarct volume compared to those without ENT (77.9 vs 24.2, P<0.001). On multivariable analysis, presence of ENT was a negative predictor of clinical outcome (mRS 0-2) after adjustment for age, sex, NIHSS, ASPECTS and successful reperfusion (OR 0.26, 95%CI 0.13-0.55).

Conclusion: The incidence of ENT was low in ESCAPE NA1 trial but associated with poorer clinical outcomes.

Abstract 17: Time-Benefit Association is Magnified in Door-To-Puncture Window: Lose 1 Second, Lose 2.2 Hours of Healthy Life

Background: The benefits of endovascular thrombectomy (EVT) are time dependent. Prior studies may have underestimated the magnitude of the time-benefit relation because time of onset (last known well ”LKW”) is imprecisely known, and analyses including late-arriving patients have under-representation of “fast-progressors.”

Methods: Patient level data were pooled by the HERMES Investigators from all 7 RCTs of stent retriever thrombectomy devices (entirely or predominantly) versus medical therapy. Analysis was confined to early-treated patients (LKW-to-puncture≤4h). Exposures: last known well-to-door (LKWTD) time; door-to-puncture (DTP) time; door-to-reperfusion (DTR) time. Outcomes: stroke-related quality of life at 3m (utility-weighted modified Rankin Scale); years of healthy life lost [disability-adjusted life years (DALYs)].

Results: Among the 781 EVT-treated patients, 406 (52.0%) were treated within 4h of LKW, with LKW-to-Door time median 188 minutes (IQR 151-215) and DTP time 105 minutes (IQR 76-135). Among the 295/372 (79.3%) with substantial reperfusion, DTR time was median 145 minutes (IQR 111-186). Care process delays were more strongly associated with worse clinical outcomes in the DTP and DTR epochs than the LKW-To-Door epoch (Table 1A), e.g., for each 10 minute delay, healthy life-years lost were: DTP 1.8 months vs LKW-to-Door 0.0 months, p < 0.0001. Considering granular time increments, the amount of healthy life-years lost associated with each 1 second of delay was: DTP 2.2 hours, DTR 2.1 hours.(Table 1B)

Conclusion: Post-arrival care delays are strongly associated with worse EVT patient outcomes in the early post-arrival time period. With every 1 second of delay in EVT delivery, patients lose 2.2 hours of healthy life-years. Continuous quality improvement to minimize delays in DTP and DTR for endovascular thrombectomy is warranted.

Abstract P535: Quality of Reperfusion and Clinical Outcome in ESCAPE-NA1 Trial

Background: We evaluated clinical outcome in relation to the degree of reperfusion in ESCAPE-NA1 trial.

Methods: ESCAPE-NA1 was a multicenter, international randomized trial assessing the efficacy of nerinetide in ischemic stroke patients who underwent EVT within 12h from onset. Independent clinical outcome [90-days modified Rankin Scale (mRS) 0-2], excellent clinical outcome (90-days mRS 0-1), isolated subarachnoid hemorrhage with no parenchymal hemorrhage (iSAH) or symptomatic hemorrhage (sICH) on follow-up imaging, and death were compared between a treatment group and control group with respect to the level of reperfusion defined as mTICI. Univariable and multivariable logistic regression analyses were performed.

Results: Data from 1090 patients were assessed. The occlusion locations were terminal ICA (18.3%), M1 MCA (61.8%,) M2 MCA (15.1%), other - e.g. M3 (3.7%). Final mTICI 0-1 was achieved in 5.5% of patients, mTICI 2a in 7.5%, mTICI 2b in 40.8%, mTICI 2c in 26.6% and mTICI 3 in 19.5%. Isolated SAH was present in 1.7% and sICH in 3%. There was no significant difference between the nerinetide and control groups in the reperfusion grade, presence of iSAH or sICH, or in clinical outcome. Odds of independent outcomes (mRS 0-2) and odds of excellent outcome (mRS 0-1) were significantly increasing with each improved reperfusion grade, Table 1. Sixty percent of patients with final mTICI 2b, 70% with mTICI 2c and 69% with mTICI 3 achieved good clinical outcome in comparison to 30% of patients with mTICI 0-2a. The incidence of iSAH was significantly lower in the NA1 arm (OR 0.28, 95%CI: 0.09-0.86, p=.027) adjusting for reperfusion status.

Conclusion: Degrees of better reperfusion are strongly associated with better outcomes and reduced mortality. mTICI 2c-3 reperfusion should be a standard goal of EVT.

Abstract P339: Evaluating Ga68 Regional Distribution as a New Pet Tracerfor Diagnosis Cerebral Amyloid Angiopathy

Introduction: The deposition of β-amyloid in cerebral vessels is an important sign of CAA. Recently, the 68Ga-P14-032 has been used in animal research. It has the ability to selectively bind a β on the cerebral vessel wall, and may become a tracer for CAA.

hypothesis: We aimed to investigate the distribution of [ 68 Ga]Ga-P14-032, a novel PET ligand that binds to vascular amyloid, in patients diagnosed clinically with probable cerebral amyloid angiopathy (CAA).

Methods: This longitudinal cohort study of 7 subjects (2 probable CAA patients, 2 AD patients, 3 normal subjects) recruited from clinics in China. All participants were aged at least 55 years with underwent [ 68 Ga]Ga-P14-032 PET/CT and PET/MR, a Montreal Cognitive Assessment (Moca) score on initial assessment. The brain PET/CT and PET/MR scans assessed through quantitative analysis. The mean cortical standardized uptake value ratio (SUVr) was calculated using cerebellum as reference. The cortex and white matter were segmented with ITK-Snap based on a T1-weighed image as the mask, leaving the scalp and the blood vessels out of the regions of interest. The corresponding PET volumes were extracted according to the masks obtained on MR and were fused with the MR images, using a MATLAB script. The images were read and interpreted by 2 doctors in nuclear medicine.Plasma levels of total-tau, amyloid-b40 and amyloid-b42 were measured by a single molecule array (Simoa) SR-X analyzer (Quanterix).

Results: Positive expression can be seen in the pathological part of microvascular in 2 CAA patients of whom had an ICH. No significant signal was seen in AD subjects or controls. Plasma levels of total-tau, amyloid-b40 and amyloid-b42 were not different among the groups.

Conclusions: Our results provide early evidence that the [68Ga]Ga-P14-032 PET probe binds preferentially to vascular amyloid, and may be a useful tracer to diagnostic of CAA. The PET marker was more sensitive to group differences than plasma assays of tau and amyloid.

Economic Evaluation of Andexanet Versus Prothrombin Complex Concentrate for Reversal of Factor Xa-Associated Intracranial Hemorrhage

[Figure: see text].

Abstract P338: Incidence, Predictors and Impact of Infarct in New Territory in Escape Na1 Trial

Introduction: Infarct in new territory (INT) is a known complication of endovascular therapy. We assessed the prevalence, predictors and clinical relevance of INT

Methods: We included patients from the ESCAPE-NA1: a multicenter, international randomized study that assessed the efficacy of intravenous nerinetide in patients with acute ischemic stroke who underwent EVT within 12 hours from onset. All imaging was re-evaluated, and INT was defined by presence of infarct in new vascular territory, outside the baseline target occlusion(s) on follow up CT and MRI. INT’s were classified by maximum diameter (<2mm, 2-20mm and >20mm) and location.

Results: Of 1099 analyzed patients in ESCAPE NA1, 107 had INT (9.7%, mean age 67 years, 51.4% females). There were no differences at baseline in those with vs without INT. Most INTs (75.7%) were angiographically occult and 41(38.3%) were > 20mm. The most common INT territory was the ACA alone or in combination with MCA/PCA (30.3%). The presence of emboli in new territory angiographically was significantly associated with INT (OR 16.39, 95%CI 8.14-33.09). Alteplase use, balloon guide catheter use, nerinetide and initial occlusion site did not predict INT. INT patients had higher final median infarct volumes compared to non-INT (44.5cc vs 23.3cc, P<0.001). Large INT (diameter of >20mm) were associated with poor clinical outcome compared to INT (<2mm) OR (mRS 0-2) 0.17, 95%CI 0.05-0.55).

Conclusion: Infarcts in new territory are common and are associated with poor outcome.

Abstract P485: Predictors and Clinical Impact of Deep Grey Matter Infarction After Endovascular Treatment for Large Vessel Occlusion Stroke: Results From the Escape-NA1 Trial

Purpose: In this post-hoc analysis of the ESCAPE-NA1 trial, we investigated the prevalence of deep grey matter infarcts and their influence on clinical outcome.

Methods: Infarcts on 24 hour follow up imaging (non contrast head CT or diffusion-weighted MRI) were categorized as predominantly deep grey matter infarcts (caudate and/or lentiform nucleus infarcts with sparing of the superficial grey matter and white matter) vs. other infarcts. Total infarct volume was manually segmented in all patients. When MRI follow-up was available, deep grey matter and grey matter infarct volumes were segmented separately. Multivariable logistic regression with adjustment for key minimization variables and by infarct volume was used to assess the association of predominantly deep grey matter infarcts and good outcome.

Results: Of the 1026 included patients, 316 (30.8%) had predominantly deep grey matter infarcts. Cumulative proportions of good outcome for overall, grey matter, deep grey matter, and superficial grey matter infarct volumes are shown in the figure. Good outcomes were more frequently achieved in patients with predominantly deep grey matter infarcts (239/316 [75.6%] vs. 374/704 [53.1%]). Deep infarcts were tightly correlated with infarct volume (Pearson rho -0.35) and in multivariable analysis deep grey matter infarcts were predictive of outcome overall; when examined in volume percentiles, there was no effect of deep infarct location.

Conclusion: Predominantly deep grey matter infarcts are associated with good outcomes. Deep grey matter infarct location favorable prognosis is associated with small overall infarct size.

Abstract P538: A Detailed Analysis of Intracranial Hemorrhage After Endovascular Treatment in Acute Ischemic Stroke Due to Large Vessel Occlusion in the Escape-NA1 Trial

Purpose: We investigated the prevalence and prognostic impact on outcome of any intracranial hemorrhage, hemorrhage morphology, type and volume in acute ischemic stroke patients undergoing mechanical thrombectomy.

Methods: Prevalence of intracranial hemorrhage, hemorrhage type, morphology and volume was determined on 24h follow-up imaging (non contrast head CT or gradient-echo/susceptibility-weighted MRI). Proportions of good outcome (mRS 0-2 at 90 days) were reported for patients with vs. without any intracranial hemorrhage. Multivariable logistic regression with adjustment for key minimization variables and total infarct volume was performed to obtain adjusted effect size estimates for hemorrhage type and volume on good outcome.

Results: Hemorrhage on follow up-imaging was seen in 372/1097 (33.9%) patients, among them 126 (33.9%) with hemorrhagic infarction (HI) type 1, 108 (29.0%) with HI-2, 72 /19.4%) with parenchymal hematoma (PH) type 1, 37 (10.0) with PH2, 8 (2.2%) with remote PH and 21 (5.7%) with extra-parenchymal/intraventricular hemorrhage. Good outcomes were less often achieved by patients with hemorrhage on follow-up imaging (164/369 [44.4%] vs. 500/720 [69.4%]). Any type of intracranial hemorrhage was strongly associated with decreased chances of good outcome ( adj OR 0.62 [CI 95 0.44 - 0.87]). The effect of hemorrhage was driven by both PH hemorrhage sub-type [PH-1 ( adj OR 0.39 [CI 95 0.21 - 0.72]), PH-2 ( adj OR 0.15 [CI 95 0.05 - 0.50])] and extra-parenchymal/intraventricular hemorrhage ( adj OR 0.60 (0.20-1.78) Petechial hemorrhages (HI-1 and HI-2) were not associated with poorer outcomes. Hemorrhage volume ( adj OR 0.97 [CI 95 0.05 - 0.99] per ml increase) was significantly associated with decreased chances of good outcome.

Conclusion: Presence of any hemorrhage on follow-up imaging was seen in one third of patients and strongly associated with decreased chances of good outcome.

Abstract MP3: Low Dose versus Standard Dose Alteplase in Acute Lacunar Ischemic Stroke

Objective: To identify any differential efficacy and safety of low- versus standard-dose intravenous alteplase for lacunar versus non-lacunar acute ischemic stroke (AIS) in the alteplase dose-arm of the Enhanced Control of Hypertension and Thrombolysis Stroke Study (ENCHANTED).

Methods: In a cohort of 3297 ENCHANTED participants, we identified those with lacunar or non-lacunar AIS with different levels of confidence (definite/probable/possible) according to pre-specified definitions based on clinical and adjudicated imaging findings. Logistic regression models were used to determine associations of lacunar AIS with 90-day outcomes (primary, modified Rankin scale [mRS] scores 2-6; secondary, other mRS scores, intracerebral hemorrhage [ICH], and early neurologic deterioration [END] or death) and treatment effects of low- versus standard-dose alteplase across lacunar and non-lacunar AIS with adjustment for baseline covariables.

Results: Of 2588 participants with available imaging and clinical data, we classified cases as definite or probable lacunar (n=490) or non-lacunar AIS (n=2098) for primary analyses. Regardless of the alteplase dose received, lacunar AIS participants had favorable functional (mRS 2-6, adjusted odds ratio [95% CI] 0.60 [0.47-0.77]) and other clinical or safety outcomes, compared to participants with non-lacunar AIS. Overall, low-dose alteplase (compared to standard) had no differential effect on the functional outcome (mRS 2-6, 1.04 [0.87-1.24]) but reduced the risk of ICH. There were no differential treatment effects of low- versus standard-dose alteplase on all outcomes across lacunar and non-lacunar AIS (all P interaction ≥0.07).

Conclusions: We found no clear evidence from the ENCHANTED trial that low-dose alteplase had any advantages over standard-dose for definite/probable lacunar AIS.

Abstract P375: Cortical Venous Opacification Patterns and Outcome in Patients With Tandem Carotid Occlusion - Results From the ESCAPE NA1-Trial

Background: The degree of cortical venous opacification could reflect the degree of ischemia in tandem occlusions strokes. We assessed the association between asymmetric cortical vein opacification and outcome among patients with acute ischemic stroke and tandem occlusion.

Methods: ESCAPE NA1 was a multicenter randomized-controlled trial comparing medical treatments nerinetide vs. placebo in patients with acute ischemic stroke and large vessel occlusion who underwent EVT. Tandem carotid occlusion was defined as complete occlusion of the ICA on catheter angiography. We assessed cortical venous opacification on baseline CTA using the COVES score (Jansen, et al. Radiology 2019, ranging from 0-6 with lower numbers indicating poor cortical venous filling, and dichotomized to 0 vs. 1-6). The influence of cortical venous opacification on functional outcome was analyzed using regression modelling with adjustment for age, baseline NIHSS and ASPECTS, thrombolysis and treatment allocation.

Results: We assessed 115 patients with tandem occlusion. Median COVES score was 2 (IQR 1-3) with 9 patients (8%) scoring 0 (complete absence of cortical venous filling). Patients with COVES 0 were less likely to have good leptomeningeal collaterals (good collaterals: COVES 0: 0/9 (0%) vs. COVES 1-6: 19/102 (18%), p = 0.007). Patients with COVES 0 were less likely to achieve good outcome (mRS 0-2, COVES 0: 3/9 patients (33%) vs. COVES 1-6: 79/106 (74%), p=0.016). Cortical venous filling was significantly associated with good functional outcome on univariable analysis (OR 5.9, 95%CI 1.4 - 25.0), and after adjustment for baseline variables (OR 8.6, 95%CI 1.4 - 51.0). Cervical carotid angioplasty and/or stenting did not modify functional outcome after adjustment for COVES score.

Conclusion: Impaired venous drainage is a marker of poor pial collaterals and is associated with poorer outcome in tandem occlusion patients.

Abstract P542: Management and Outcome of Stroke Patients With Tandem Carotid Occlusion in the ESCAPE NA1-Trial

Background: The optimal treatment for stroke patients with tandem cervical carotid occlusion is debated. We analyzed the treatment strategies and outcomes of tandem occlusion patients in the ESCAPE NA1 trial.

Methods: ESCAPE NA1 was a multicenter international randomized trial of nerinetide vs. placebo in patients with acute ischemic stroke who underwent EVT. We defined tandem occlusions as complete occlusion of the cervical ICA on catheter angiography. The influence of tandem occlusions on outcome was analyzed using regression modeling with adjustment for age, sex, baseline NIHSS and ASPECTS, occlusion location, thrombolysis and treatment allocation.

Results: 115 of 1105 patients (10.4%) had tandem occlusions. 73/115 tandem patients (66.0%) received treatment for the cervical occlusion: 21.9% were stented before thrombectomy, 68.5% were stented after thrombectomy, and 8.2% had angioplasty alone. Successful reperfusion was significantly higher in patients who had thrombectomy first followed by carotid treatment (eTICI 2b-3: 40/40 (100.0%)) or carotid angioplasty before and cervical stent after intracranial thrombectomy (9/10 (90.0%)) compared to carotid intervention before intracranial thrombectomy: (19/23 (82.1%), p=0.016). 90-day mRS 0-2 was achieved in 82/115 patients (71.3%) with tandem occlusions (treated occlusions: 74.0%, untreated: 66.7%) compared to 579/981 (59.5%) patients without tandem occlusions. In adjusted analysis, tandem occlusion was not predictive of outcome. In the subgroup of tandem patients, cervical stent-treatment was nominally associated with better outcomes (OR 2.2, 95% CI 0.5 - 9.2).

Conclusion: Cervical carotid stenting may improve outcomes for EVT patients with tandem occlusions, but these results are limited by the sample size and non-randomized selection of patients for stenting.

Abstract P490: Influence of Balloon Guide Catheter Use on Procedural & Clinical Outcomes in the Escape-NA1 Trial

Purpose: We assessed whether balloon guide catheter (BGC) use during endovascular thrombectomy (EVT) influences procedural and clinical outcomes in the ESCAPE-NA1 trial.

Methods: ESCAPE-NA1 was an international multicenter trial that randomized large vessel occlusion stroke patients who underwent endovascular thrombectomy (EVT) to receive Nerinetide vs. placebo. Information on EVT techniques and devices was extracted from angiographic images and procedure report forms. Effect estimates of BGC use on angiographic and clinical outcomes were obtained with logistic regression with adjustment for age, ASPECTS, baseline NIHSS, occlusion site, alteplase and study drug treatment.

Results: Detailed information on EVT devices and technique was available for 891/1105 (80.6%) patients. A BGC was used in 599/891 patients (67.2%). BGC use was most common with a retrievable stent use (with or without distal access catheter) as the first-line approach (in 252/266 cases [94.7%] vs. combined approach (both aspiration and SR): 288/414 [69.6%], vs. contact aspiration: 37/159 cases [23.3%]). Overall, eTICI 2b/3 rates with vs. without BGC did not differ significantly (525/598 [87.8%] vs. 260/292 [89.0%]), but eTICI 2c/3 rates were significantly higher when a BGC was used (304/598 [50.8%] vs. 126/292 [43.2%], adjusted OR 1.39 [95%CI 1.05 - 1.9]). Good outcomes (mRS 0-2) were not associated with BGC use (adjusted OR 1.07 [95%CI 0.78 - 1.48]).

Conclusion: BGC use was associated with a greater proportion of near-complete reperfusion, while there was no significant association with clinical outcomes.

Low-Dose vs Standard-Dose Alteplase in Acute Lacunar Ischemic Stroke: The ENCHANTED Trial

OBJECTIVE

To determine any differential efficacy and safety of low- vs standard-dose IV alteplase for lacunar vs nonlacunar acute ischemic stroke (AIS), we performed post hoc analyzes from the Enhanced Control of Hypertension and Thrombolysis Stroke Study (ENCHANTED) alteplase dose arm.

METHODS

In a cohort of 3,297 ENCHANTED participants, we identified those with lacunar or nonlacunar AIS with different levels of confidence (definite/according to prespecified definitions based on clinical and adjudicated imaging findings. Logistic regression models were used to determine associations of lacunar AIS with 90-day outcomes (primary, modified Rankin Scale [mRS] scores 2-6; secondary, other mRS scores, intracerebral hemorrhage [ICH], and early neurologic deterioration or death) and treatment effects of low- vs standard-dose alteplase across lacunar and nonlacunar AIS with adjustment for baseline covariables.

RESULTS

Of 2,588 participants with available imaging and clinical data, we classified cases as definite/probable lacunar (n = 490) or nonlacunar AIS (n = 2,098) for primary analyses. Regardless of alteplase dose received, lacunar AIS participants had favorable functional (mRS 2-6, adjusted odds ratio [95% confidence interval] 0.60 [0.47-0.77]) and other clinical or safety outcomes compared to participants with nonlacunar AIS. Low-dose alteplase (versus standard) had no differential effect on functional outcomes (mRS 2-6, 1.04 [0.87-1.24]) but reduced the risk of symptomatic ICH in all included participants. There were no differential treatment effects of low- vs standard-dose alteplase on all outcomes across lacunar and nonlacunar AIS (all p _interaction ≥0.07).

CONCLUSIONS

We found no evidence from the ENCHANTED trial that low-dose alteplase had any advantages over standard dose for definite/probable lacunar AIS.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that for patients with lacunar AIS, low-dose alteplase had no additional benefit or safety over standard-dose alteplase.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov identifier NCT01422616.

Thrombus Migration and Fragmentation After Intravenous Alteplase Treatment: The INTERRSeCT Study

BACKGROUND AND PURPOSE

There is interest in what happens over time to the thrombus after intravenous alteplase. We study the effect of alteplase on thrombus structure and its impact on clinical outcome in patients with acute stroke.

METHODS

Intravenous alteplase treated stroke patients with intracranial internal carotid artery or middle cerebral artery occlusion identified on baseline computed tomography angiography and with follow-up vascular imaging (computed tomography angiography or first run of angiography before endovascular therapy) were enrolled from INTERRSeCT study (Identifying New Approaches to Optimize Thrombus Characterization for Predicting Early Recanalization and Reperfusion With IV Alteplase and Other Treatments Using Serial CT Angiography). Thrombus movement after intravenous alteplase was classified into complete recanalization, thrombus migration, thrombus fragmentation, and no change. Thrombus migration was diagnosed when occlusion site moved distally and graded according to degrees of thrombus movement (grade 0-3). Thrombus fragmentation was diagnosed when a new distal occlusion in addition to the primary occlusion was identified on follow-up imaging. The association between thrombus movement and clinical outcome was also evaluated.

RESULTS

Among 427 patients in this study, thrombus movement was seen in 54% with a median time of 123 minutes from alteplase administration to follow-up imaging, and sub-classified as marked (thrombus migration grade 2-3 + complete recanalization; 27%) and mild to moderate thrombus movement (thrombus fragmentation + thrombus migration grade 0-1; 27%). In patients with proximal M1/internal carotid artery occlusion, marked thrombus movement was associated with a higher rate of good outcome (90-day modified Rankin Scale, 0-2) compared with mild to moderate movement (52% versus 27%; adjusted odds ratio, 5.64 [95% CI, 1.72-20.10]). No difference was seen in outcomes between mild to moderate thrombus movement and no change. In M1 distal/M2 occlusion, marked thrombus movement was associated with improved 90-day good outcome compared with no change (70% versus 56%; adjusted odds ratio, 2.54 [95% CI, 1.21-5.51]).

CONCLUSIONS

Early thrombus movement is common after intravenous alteplase. Marked thrombus migration leads to good clinical outcomes. Thrombus dynamics over time should be further evaluated in clinical trials of acute reperfusion therapy.

Computed Tomography Perfusion-Based Machine Learning Model Better Predicts Follow-Up Infarction in Patients With Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Prediction of infarct extent among patients with acute ischemic stroke using computed tomography perfusion is defined by predefined discrete computed tomography perfusion thresholds. Our objective is to develop a threshold-free computed tomography perfusion-based machine learning (ML) model to predict follow-up infarct in patients with acute ischemic stroke.

METHODS

Sixty-eight patients from the PRoveIT study (Measuring Collaterals With Multi-Phase CT Angiography in Patients With Ischemic Stroke) were used to derive a ML model using random forest to predict follow-up infarction voxel by voxel, and 137 patients from the HERMES study (Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke Trials) were used to test the derived ML model. Average map, T_max, cerebral blood flow, cerebral blood volume, and time variables including stroke onset-to-imaging and imaging-to-reperfusion time, were used as features to train the ML model. Spatial and volumetric agreement between the ML model predicted follow-up infarct and actual follow-up infarct were assessed. Relative cerebral blood flow <0.3 threshold using RAPID software and time-dependent T_max thresholds were compared with the ML model.

RESULTS

In the test cohort (137 patients), median follow-up infarct volume predicted by the ML model was 30.9 mL (interquartile range, 16.4-54.3 mL), compared with a median 29.6 mL (interquartile range, 11.1-70.9 mL) of actual follow-up infarct volume. The Pearson correlation coefficient between 2 measurements was 0.80 (95% CI, 0.74-0.86, P<0.001) while the volumetric difference was -3.2 mL (interquartile range, -16.7 to 6.1 mL). Volumetric difference with the ML model was smaller versus the relative cerebral blood flow <0.3 threshold and the time-dependent T_max threshold (P<0.001).

CONCLUSIONS

A ML using computed tomography perfusion data and time estimates follow-up infarction in patients with acute ischemic stroke better than current methods.

Intensive versus guideline-recommended blood pressure reduction in acute lacunar stroke with intravenous thrombolysis therapy: The ENCHANTED trial

BACKGROUND AND PURPOSE

This was an investigation of the differential effects of early intensive versus guideline-recommended blood pressure (BP) lowering between lacunar and non-lacunar acute ischaemic stroke (AIS) in the BP arm of the Enhanced Control of Hypertension and Thrombolysis Stroke Study (ENCHANTED).

METHODS

In 1,632 participants classified as having definite or probable lacunar (n = 454 [27.8%]) or non-lacunar AIS according to pre-specified definitions based upon clinical and adjudicated imaging findings, mean BP changes over days 0-7 were plotted, and systolic BP differences by treatment between subgroups were estimated in generalized linear models. Logistic regression models were used to estimate the BP treatment effects on 90-day outcomes (primary, an ordinal shift of modified Rankin scale scores) across lacunar and non-lacunar AIS after adjustment for baseline covariables.

RESULTS

Most baseline characteristics, acute BP and other management differed between lacunar and non-lacunar AIS, but mean systolic BP differences by treatment were comparable at each time point (all p_interaction  > 0.12) and over 24 h post-randomization (-5.5, 95% CI -6.5, -4.4 mmHg in lacunar AIS vs. -5.6, 95% CI -6.3, -4.8 mmHg in non-lacunar AIS, p_interaction  = 0.93). The neutral effect of intensive BP lowering on functional outcome and the beneficial effect on intracranial haemorrhage were similar for the two subgroups (all p_interaction  > 0.19).

CONCLUSIONS

There were no differences in the treatment effect of early intensive versus guideline-recommended BP lowering across lacunar and non-lacunar AIS.

Defining reperfusion post endovascular therapy in ischemic stroke using MR-dynamic contrast enhanced perfusion

OBJECTIVES

Cerebral blood flow (CBF) measurements after endovascular therapy (EVT) for acute ischemic stroke are important to distinguish early secondary injury related to persisting ischemia from that related to reperfusion when considering clinical response and infarct growth.

METHODS

We compare reperfusion quantified by the modified Thrombolysis in Cerebral Infarction Score (mTICI) with perfusion measured by MRI dynamic contrast-enhanced perfusion within 5 h of EVT anterior circulation stroke. MR perfusion (rCBF, rCBV, rTmax, rT0) and mTICI scores were included in a predictive model for change in NIHSS at 24 h and diffusion-weighted imaging (DWI) lesion growth (acute to 24 h MRI) using a machine learning RRELIEFF feature selection coupled with a support vector regression.

RESULTS

For all perfusion parameters, mean values within the acute infarct for the TICI-2b group (considered clinically good reperfusion) were not significantly different from those in the mTICI <2b (clinically poor reperfusion). However, there was a statistically significant difference in perfusion values within the acute infarct region of interest between the mTICI-3 group versus both mTICI-2b and <2b (p = 0.02). The features that made up the best predictive model for change in NIHSS and absolute DWI lesion volume change was rT0 within acute infarct ROI and admission CTA collaterals respectively. No other variables, including mTICI scores, were selected for these best models. The correlation coefficients (Root mean squared error) for the cross-validation were 0.47 (13.7) and 0.51 (5.7) for change in NIHSS and absolute DWI lesion volume change.

CONCLUSION

MR perfusion following EVT provides accurate physiological approach to understanding the relationship of CBF, clinical outcome, and DWI growth.

ADVANCES IN KNOWLEDGE

MR perfusion CBF acquired is a robust, objective reperfusion measurement providing following recanalization of the target occlusion which is critical to distinguish potential therapeutic harm from the failed technical success of EVT as well as improve the responsiveness of clinical trial outcomes to disease modification.

Imaging criteria across pivotal randomized controlled trials for late window thrombectomy patient selection

BACKGROUND

The DAWN and DEFUSE-3 trials showed the benefit of endovascular treatment (EVT) in acute ischemic stroke patients presenting beyond 6 hours from last known well (LKW) and selected by perfusion imaging criteria. The ESCAPE NA1-trial selected patients based on non-contrast CT (NCCT) Alberta Stroke Program Early CT Score (ASPECTS) and multiphase CT angiography (CTA) collateral status. This study compares baseline characteristics, workflow, and outcomes in the EVT arms of DAWN and DEFUSE-3 with late-window patients from the EVT-only arm of ESCAPE-NA1.

METHODS

Aggregate data on baseline characteristics, workflow, reperfusion quality, final infarct volume, and clinical outcomes (modified Rankin Score [mRS] at 90 days) in subjects enrolled in the DAWN and DEFUSE-3 EVT arms were compared with similar data from the ESCAPE-NA1 control arm (EVT-only arm) presenting beyond 6 hours from LKW using descriptive statistics.

RESULTS

Baseline characteristics among late-window patients in the ESCAPE NA1 trial were similar to those in the DAWN and DEFUSE-3 EVT arms. Median time from LKW-to-puncture in subjects enrolled in the ESCAPE NA1 trial was 9 hrs (IQR: 7.5-11 hours) when compared with DAWN (n=107; 12.8 hours, IQR: 10.6-16.7 hours) and DEFUSE-3 (n=92; 11.5 hours, IQR: 9.2-12.8 hours). Median post-treatment infarct-volume was largest in the ESCAPE NA1-patients (47 mL [IQR: 19-146] vs median 8 mL [IQR: 0-48] in the DAWN group and 35 mL [IQR: 18-82] in DEFUSE-3), while % mRS 0-2 at 90 days were similar across the three trials (ESCAPE NA1: 50/111 [45%], DAWN: 52/107 [49%], DEFUSE-3: 41/92 [45%]).

CONCLUSION

Patients enrolled beyond 6 hours from LKW in the ESCAPE-NA1 trial based on NCCT-ASPECTS and mCTA had similar clinical outcomes when compared with patients selected by perfusion imaging in the DAWN and DEFUSE-3 trials.

Early Recanalization With Alteplase in Stroke Because of Large Vessel Occlusion in the ESCAPE Trial

BACKGROUND AND PURPOSE

Quantitating the effect of intravenous alteplase on the technical outcome of early recanalization of large vessel occlusions aids understanding. We report the prevalence of early recanalization in patients with stroke because of large vessel occlusion treated with and without intravenous alteplase and endovascular thrombectomy, and its association with clinical outcome.

METHODS

Patients with acute ischemic stroke with large vessel occlusion from the ESCAPE trial (Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion With Emphasis on Minimizing CT to Recanalization Times Trial) were included in this post hoc analysis. Outcomes of interest were the prevalence of early recanalization (1) and good outcome (2), defined as modified Rankin Scale score of 0 to 2 at 90 days.

RESULTS

Among 147 patients who did not receive endovascular thrombectomy, early recanalization occurred in 4/30 (13.3%) patients without and 48/117 (41.0%) patients with intravenous alteplase (adjusted risk ratios, 3.2 [95% CI, 1.2-8.1]). Good outcome was achieved by 34/116 (29.3%) of patients who received intravenous alteplase versus 10/29 (34.5%) who did not receive alteplase (adjusted risk ratios, 1.0 [95% CI, 0.6-1.5) and by 20/52 (38.5%) patients with versus 24/93 (25.8%) without early recanalization (adjusted risk ratios, 1.9 [95% CI, 1.2-2.9]).

CONCLUSIONS

Early recanalization was confirmed as a strong predictor of good outcome in patients who did not undergo endovascular thrombectomy and was improved with intravenous alteplase, yet a majority of patients (59.0%) did not achieve early reperfusion. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01778335.