Influence of Infarct Morphology and Patterns on Cognitive Outcomes After Endovascular Thrombectomy

BACKGROUND

To assess the association of qualitative and quantitative infarct characteristics and 3 cognitive outcome tests, namely the Montreal Cognitive Assessment (MOCA) for mild cognitive impairment, the Boston Naming Test for visual confrontation naming, and the Sunnybrook Neglect Assessment Procedure for neglect, in large vessel occlusion stroke.

METHODS

Secondary observational cohort study using data from the randomized-controlled ESCAPE-NA1 trial (Safety and Efficacy of Nerinetide in Subjects Undergoing Endovascular Thrombectomy for Stroke), in which patients with large vessel occlusion undergoing endovascular treatment were randomized to receive either intravenous Nerinetide or placebo. MOCA, Sunnybrook Neglect Assessment Procedure, and 15-item Boston Naming Test were obtained at 90 days. Total infarct volume, gray matter, and white matter infarct volumes were manually measured on 24-hour follow-up imaging. Infarcts were also visually classified as either involving the gray matter only or both the gray and white matter and scattered versus territorial. Associations of infarct variables and cognitive outcomes were analyzed using multivariable ordinal or binary logistic regression models.

RESULTS

Of 1105 patients enrolled in ESCAPE-NA1, 1026 patients with visible infarcts on 24-hour follow-up imaging were included. MOCA and Sunnybrook Neglect Assessment Procedure were available for 706 (68.8%) patients and the 15-item Boston Naming Test was available for 682 (66.5%) patients. Total infarct volume was associated with worse MOCA scores (adjusted common odds ratio per 10 mL increase, 1.05 [95% CI, 1.04-1.06]). After adjusting for baseline variables and total infarct volume, mixed gray and white matter involvement (versus gray matter-only adjusted common odds ratio, 1.92 [95% CI, 1.37-2.69]), white matter infarct volume (adjusted common odds ratio per 10 mL increase 1.36 [95% CI, 1.18-1.58]) and territorial (versus scattered) infarct pattern (adjusted common odds ratio, 1.65 [95% CI, 1.15-2.38]) were associated with worse MOCA scores. Results for Sunnybrook Neglect Assessment Procedure and 15-item Boston Naming Test were similar, except for the territorial infarct pattern, which did not reach statistical significance in multivariable analysis.

CONCLUSIONS

Besides total infarct volume, infarcts that involve the white matter and that show a territorial distribution were associated with worse cognitive outcomes, even after adjusting for total infarct volume.

Modeling diffusion-weighted imaging lesion expansion between 2 and 24 h after endovascular thrombectomy in acute ischemic stroke

PURPOSE

Diffusion-weighted imaging (DWI) lesion expansion after endovascular thrombectomy (EVT) is not well characterized. We used serial diffusion-weighted magnetic resonance imaging (MRI) to measure lesion expansion between 2 and 24 h after EVT.

METHODS

In this single-center observational analysis of patients with acute ischemic stroke due to large vessel occlusion, DWI was performed post-EVT (< 2 h after closure) and 24-h later. DWI lesion expansion was evaluated using multivariate generalized linear mixed modeling with various clinical moderators.

RESULTS

We included 151 patients, of which 133 (88%) had DWI lesion expansion, defined as a positive change in lesion volume between 2 and 24 h. In an unadjusted analysis, median baseline DWI lesion volume immediately post-EVT was 15.0 mL (IQR: 6.6-36.8) and median DWI lesion volume 24 h post-EVT was 20.8 mL (IQR: 9.4-66.6), representing a median change of 6.1 mL (IQR: 1.5-17.7), or a 39% increase. There were no significant associations among univariable models of lesion expansion. Adjusted models of DWI lesion expansion demonstrated that relative lesion expansion (defined as final/initial DWI lesion volume) was consistent across eTICI scores (0-2a, 0.52%; 2b, 0.49%; 2c-3, 0.42%, p = 0.69). For every 1 mL increase in lesion volume, there was 2% odds of an increase in 90-day mRS (OR: 1.021, 95%CI [1.009, 1.034], p < 0.001).

CONCLUSION

We observed substantial lesion expansion post-EVT whereby relative lesion expansion was consistent across eTICI categories, and greater absolute lesion expansion was associated with worse clinical outcome. Our findings suggest that alternate endpoints for cerebroprotectant trials may be feasible.

Discordance in tests used to detect inhibition of the P2Y12 receptor in patients undergoing interventional neuroradiology procedures

BACKGROUND

Clopidogrel is an inhibitor of the P2Y12 platelet receptor but testing to demonstrate a drug effect is controversial since there are often discordant results between different tests methods.

METHODS

Samples from patients taking clopidogrel prior to intracranial flow-diversion procedures were tested using light transmission aggregometry (LTA), whole blood impedance aggregometry (WBIA) and the VerifyNow device (VND). Samples were classified as concordant if all test results were either responsive (inhibition) or resistant. Discordant results were separated using the VND into those with a responsive versus a resistant test result.

RESULTS

Samples from 96 patients were studied. Concordance for all three tests was seen in 53/96 (55%) of samples, of which 41 (43%) were responsive and 12 (12%) were resistant. Discordance was observed in 43 samples (45%), 37 (28%) of which were caused by responsive VND and either a resistant WBIA or LTA and 6 (7%) of which were caused by a resistant VND but a responsive test result using either WBIA or LTA. These two discordant groups differed in both platelet count and hematocrit, but no such difference was present between the two concordant groups.

CONCLUSION

Discordance in P2Y12 inhibition testing may be partly explained by sample platelet count and hematocrit.

Dual antiplatelet use in the management of COVID-19 associated acute ischemic stroke reocclusion

INTRO

SARS-CoV-2 (COVID-19) infection is associated with acute ischemic stroke (AIS), which may be due to a prothrombotic state. Early reports have suggested high rates of reocclusion following mechanical thrombectomy (MT) with poor radiographic and clinical outcomes. We report our early experience using intra-procedural antithrombotics to address SARS-CoV-2 reocclusion.

METHODS

We identified 6 patients that experienced early reocclusion after MT for COVID-19-associated AIS through retrospective chart review abstracting their basic demographics, COVID-19 status, and stroke management. All these patients were treated after reocclusion with aspirin and cangrelor intra-procedurally, the latter of which was converted to ticagrelor post-procedurally. Some patients additionally received argatroban infusion intraprocedurally.

RESULTS

Mean age was 54. There were 3 post-procedural and 3 intra-procedural re-occlusions. After repeat thrombectomy and treatment with aspirin and cangrelor, those with post-procedure reocclusion did not show further reocclusion, while those with intra-procedural reocclusion showed radiographic improvement with intraprocedural cangrelor administration. Outcomes for these patients were poor, with a median mRS of 4. Two patients developed petechial hemorrhage of their stroke which was managed conservatively, and one developed a retroperitoneal hemorrhage from femoral access requiring transfusion. There were no patients who developed new parenchymal hematomas.

CONCLUSION

COVID-19 AIS may be associated with a hypercoagulable state which risks malignant reocclusion complicating MT. We found antithrombotic treatment periprocedural cangrelor with or without argatroban transitioned to oral aspirin with ticagrelor to be a viable method for management of these patients.

Risk of recurrent stroke in patients with atrial fibrillation treated with oral anticoagulants alone or in combination with anti-platelet therapy

INTRODUCTION

Ischaemic stroke patients with atrial fibrillation (AF) are at high risk of stroke recurrence despite oral anticoagulation therapy. Patients with cardiovascular comorbidities may take both antiplatelet and oral anticoagulation therapy (OAC/AP). Our study aims to evaluate the safety and efficacy of OAC/AP therapy as secondary prevention in people with AF and ischaemic stroke.

PATIENTS AND METHODS

We performed a post-hoc analysis of pooled individual data from multicenter prospective cohort studies and compared outcomes in the OAC/AP cohort and patients on DOAC/VKA anticoagulation alone (OAC cohort). Primary outcome was a composite of ischaemic stroke, systemic embolism, intracranial bleeding, and major extracranial bleeding, while secondary outcomes were ischaemic and haemorrhagic events considered separately. A multivariable logistic regression analysis was performed to identify independent predictors for outcome events. To compare the risk of outcome events between the two cohorts, the relation between the survival function and the set of explanatory variables were calculated by Cox proportional hazard models and the results were reported as adjusted hazard ratios (HR). Finally another analysis was performed to compare the overall risk of outcome events in both OAC/AP and OAC cohorts after propensity score matching (PSM).

RESULTS

During a mean follow-up time of 7.5 ± 9.1 months (median follow-up time 3.5 months, interquartile range ±3), 2284 stroke patients were on oral anticoagulants and 215 were on combined therapy. The multivariable model demonstrated that the composite outcome is associated with age (OR: 1.03, 95% CI: 1.01-1.04 for each year increase) and concomitant antiplatelet therapy (OR: 2.2, 95% CI: 1.48-3.27), the ischaemic outcome with congestive heart failure (OR: 1.55, 95% CI: 1.02-2.36) and concomitant antiplatelet therapy (OR: 1.93, 95% CI: 1.19-3.13) and the haemorrhagic outcome with age (OR: 1.03, 95% CI: 1.01-1.06 for each year increase), alcoholism (OR: 2.15, 95% CI: 1.06-4.39) and concomitant antiplatelet therapy (OR: 2.22, 95% CI: 1.23-4.02). Cox regression demonstrated a higher rate of the composite outcome (hazard ratio of 1.93 [95% CI, 1.35-2.76]), ischaemic events (HR: 2.05 [95% CI: 1.45-2.87]) and bleeding outcomes (HR: 1.90 [95% CI, 1.06-3.40]) in OAC/AP cohort. After PSM analysis, the composite outcome remained more frequent in people treated with OAC + AP (RR: 1.70 [95% CI, 1.05-2.74]).

DISCUSSION

Secondary prevention with combination of oral anticoagulant and antiplatelet therapy after ischaemic stroke was associated with worse outcomes in our cohort.

CONCLUSION

Further research is needed to improve secondary prevention by investigating the mechanisms of recurrent ischaemic stroke in patients with atrial fibrillation.

Recurrent Ischemic Stroke and Bleeding in Patients With Atrial Fibrillation Who Suffered an Acute Stroke While on Treatment With Nonvitamin K Antagonist Oral Anticoagulants: The RENO-EXTEND Study

BACKGROUND

In patients with atrial fibrillation who suffered an ischemic stroke while on treatment with nonvitamin K antagonist oral anticoagulants, rates and determinants of recurrent ischemic events and major bleedings remain uncertain.

METHODS

This prospective multicenter observational study aimed to estimate the rates of ischemic and bleeding events and their determinants in the follow-up of consecutive patients with atrial fibrillation who suffered an acute cerebrovascular ischemic event while on nonvitamin K antagonist oral anticoagulant treatment. Afterwards, we compared the estimated risks of ischemic and bleeding events between the patients in whom anticoagulant therapy was changed to those who continued the original treatment.

RESULTS

After a mean follow-up time of 15.0±10.9 months, 192 out of 1240 patients (15.5%) had 207 ischemic or bleeding events corresponding to an annual rate of 13.4%. Among the events, 111 were ischemic strokes, 15 systemic embolisms, 24 intracranial bleedings, and 57 major extracranial bleedings. Predictive factors of recurrent ischemic events (strokes and systemic embolisms) included CHA₂DS₂-VASc score after the index event (odds ratio [OR], 1.2 [95% CI, 1.0-1.3] for each point increase; P=0.05) and hypertension (OR, 2.3 [95% CI, 1.0-5.1]; P=0.04). Predictive factors of bleeding events (intracranial and major extracranial bleedings) included age (OR, 1.1 [95% CI, 1.0-1.2] for each year increase; P=0.002), history of major bleeding (OR, 6.9 [95% CI, 3.4-14.2]; P=0.0001) and the concomitant administration of an antiplatelet agent (OR, 2.8 [95% CI, 1.4-5.5]; P=0.003). Rates of ischemic and bleeding events were no different in patients who changed or not changed the original nonvitamin K antagonist oral anticoagulants treatment (OR, 1.2 [95% CI, 0.8-1.7]).

CONCLUSIONS

Patients suffering a stroke despite being on nonvitamin K antagonist oral anticoagulant therapy are at high risk of recurrent ischemic stroke and bleeding. In these patients, further research is needed to improve secondary prevention by investigating the mechanisms of recurrent ischemic stroke and bleeding.

Ipsilateral internal carotid artery web and acute ischemic stroke: A cohort study, systematic review and meta-analysis

Introduction

The carotid web is a compelling potential mechanism of embolic ischemic stroke. In this study, we aim to determine the prevalence of ipsilateral carotid web in a cohort of ischemic stroke patients and to perform a systematic review and meta-analysis of similar cohorts.

Patients & methods

We performed a retrospective, observational, cohort study of acute ischemic stroke patients admitted to a comprehensive stroke center from June 2012 to September 2017. Carotid web was defined on computed tomography angiography (CTA) as a thin shelf of non-calcified tissue immediately distal to the carotid bifurcation. We described the prevalence of carotid artery webs in our cohort, then performed a systematic review and meta-analysis of similar cohorts in the published literature.

Results

We identified 1,435 potentially eligible patients of whom 879 met criteria for inclusion in our analysis. An ipsilateral carotid web was detected in 4 out of 879 (0.45%) patients, of which 4/4 (1.6%) were in 244 patients with cryptogenic stroke and 3/4 were in 66 (4.5%) patients <60 years old with cryptogenic stroke. Our systematic review yielded 3,192 patients. On meta-analysis, the pooled prevalence of ipsilateral carotid web in cryptogenic stroke patients <60 was 13% (95% CI: 7%-22%; I² = 66.1%). The relative risk (RR) of ipsilateral versus contralateral carotid web in all patients was 2.5 (95% CI 1.5–4.2, p = 0.0009) whereas in patients less than 60 with cryptogenic stroke it was 3.0 (95% CI 1.6–5.8, p = 0.0011).

Discussion

Carotid webs are more common in young patients with cryptogenic stroke than in other stroke subtypes. Future studies concerning the diagnosis and secondary prevention of stroke associated with carotid web should focus on this population.

Strength of Association between Infarct Volume and Clinical Outcome Depends on the Magnitude of Infarct Size: Results from the ESCAPE-NA1 Trial

BACKGROUND AND PURPOSE

Infarct volume is an important predictor of clinical outcome in acute stroke. We hypothesized that the association of infarct volume and clinical outcome changes with the magnitude of infarct size.

MATERIALS AND METHODS

Data were derived from the Safety and Efficacy of Nerinetide in Subjects Undergoing Endovascular Thrombectomy for Stroke (ESCAPE-NA1) trial, in which patients with acute stroke with large-vessel occlusion were randomized to endovascular treatment plus either nerinetide or a placebo. Infarct volume was manually segmented on 24-hour noncontrast CT or DWI. The relationship between infarct volume and good outcome, defined as mRS 0-2 at 90 days, was plotted. Patients were categorized on the basis of visual grouping at the curve shoulders of the infarct volume/outcome plot. The relationship between infarct volume and adjusted probability of good outcome was fitted with linear or polynomial functions as appropriate in each group.

RESULTS

We included 1099 individuals in the study. Median infarct volume at 24 hours was 24.9 mL (interquartile range [IQR] = 6.6-92.2 mL). On the basis of the infarct volume/outcome plot, 4 infarct volume groups were defined (IQR = 0-15 mL, 15.1-70 mL, 70.1-200 mL, >200 mL). Proportions of good outcome in the 4 groups were 359/431 (83.3%), 219/337 (65.0%), 71/201 (35.3%), and 16/130 (12.3%), respectively. In small infarcts (IQR = 0-15 mL), no relationship with outcome was appreciated. In patients with intermediate infarct volume (IQR = 15-200 mL), there was progressive importance of volume as an outcome predictor. In infarcts of > 200 mL, outcomes were overall poor.

CONCLUSIONS

The relationship between infarct volume and clinical outcome varies nonlinearly with the magnitude of infarct size. Infarct volume was linearly associated with decreased chances of achieving good outcome in patients with moderate-to-large infarcts, but not in those with small infarcts. In very large infarcts, a near-deterministic association with poor outcome was seen.

Penumbra Consumption Rates Based on Time-to-Maximum Delay and Reperfusion Status: A Post Hoc Analysis of the DEFUSE 3 Trial

BACKGROUND AND PURPOSE

In patients with acute large vessel occlusion, the natural history of penumbral tissue based on perfusion time-to-maximum (T_max) delay is not well established in relation to late-window endovascular thrombectomy. In this study, we sought to evaluate penumbra consumption rates for T_max delays in patients with large vessel occlusion evaluated between 6 and 16 hours from last known normal.

METHODS

This is a post hoc analysis of the DEFUSE 3 trial (The Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke), which included patients with an acute ischemic stroke due to anterior circulation occlusion within 6 to 16 hours of last known normal. The primary outcome is percentage penumbra consumption, defined as (24-hour magnetic resonance imaging infarct volume-baseline core infarct volume)/(T_max 6 or 10 s volume-baseline core volume). We stratified the cohort into 4 categories based on treatment modality and Thrombolysis in Cerebral Infarction (TICI score; untreated, TICI 0-2a, TICI 2b, and TICI3) and calculated penumbral consumption rates in each category.

RESULTS

We included 141 patients, among whom 68 were untreated. In the untreated versus TICI 3 patients, a median (interquartile range) of 53.7% (21.2%-87.7%) versus 5.3% (1.1%-14.6%) of penumbral tissue was consumed based on T_max >6 s (P<0.001). In the same comparison for T_max>10 s, we saw a difference of 165.4% (interquartile range, 56.1%-479.8%) versus 25.7% (interquartile range, 3.2%-72.1%; P<0.001). Significant differences were not demonstrated between untreated and TICI 0-2a patients for penumbral consumption based on T_max >6 s (P=0.52) or T_max >10 s (P=0.92).

CONCLUSIONS

Among extended window endovascular thrombectomy patients, T_max >10-s mismatch volume may comprise large volumes of salvageable tissue, whereas nearly half the T_max >6-s mismatch volume may remain viable in untreated patients at 24 hours.

Radiologic Patterns of Intracranial Hemorrhage and Clinical Outcome after Endovascular Treatment in Acute Ischemic Stroke: Results from the ESCAPE-NA1 Trial

Background Intracranial hemorrhage is a known complication after endovascular treatment in patients with acute ischemic stroke due to large vessel occlusion, but the association between radiologic hemorrhage severity and outcome is controversial. Purpose To investigate the prevalence and impact on outcome of intracranial hemorrhage and hemorrhage severity after endovascular stroke treatment. Materials and Methods The Efficacy and Safety of Nerinetide for the Treatment of Acute Ischemic Stroke (ESCAPE-NA1) trial enrolled participants with acute large vessel occlusion stroke who underwent endovascular treatment from March 1, 2017, to August 12, 2019. Evidence of any intracranial hemorrhage, hemorrhage multiplicity, and radiologic severity, according to the Heidelberg classification (hemorrhagic infarction type 1 [HI1], hemorrhagic infarction type 2 [HI2], parenchymal hematoma type 1 [PH1], and parenchymal hematoma type 2 [PH2]) was assessed at CT or MRI 24 hours after endovascular treatment. Good functional outcome, defined as a modified Rankin score of 0-2 at 90 days, was compared between participants with intracranial hemorrhage and those without intracranial hemorrhage at follow-up imaging and between hemorrhage subtypes. Poisson regression was performed to obtain adjusted effect size estimates for the presence of any intracranial hemorrhage and hemorrhage subtypes at good functional outcome. Results Of 1097 evaluated participants (mean age, 69 years ± 14 [standard deviation]; 551 men), any degree of intracranial hemorrhage was observed in 372 (34%). Good outcomes were less often achieved among participants with hemorrhage than among those without hemorrhage at follow-up imaging (164 of 372 participants [44%] vs 500 of 720 [69%], respectively; P < .01). After adjusting for baseline variables and infarct volume, intracranial hemorrhage was not associated with decreased chances of good outcome (adjusted risk ratio [RR] = 0.91 [95% CI: 0.82, 1.02], P = .10), but there was a graded relationship of radiologic hemorrhage severity and outcomes, whereby PH1 (RR = 0.77 [95% CI: 0.61, 0.97], P = .03) and PH2 (RR = 0.41 [95% CI: 0.21, 0.81], P = .01) were associated with decreased chances of good outcome. Conclusion Any degree of intracranial hemorrhage after endovascular treatment was seen in one-third of participants. A graded association existed between radiologic hemorrhage severity and outcome. Hemorrhagic infarction was not associated with outcome, whereas parenchymal hematoma was strongly associated with poor outcome, independent of infarct volume. © RSNA, 2021 Clinical trial registration no. NCT01778335 Online supplemental material is available for this article.

Clinical impact of EVT with failed reperfusion in patients with acute ischemic stroke: results from the ESCAPE and ESCAPE-NA1 trials

BACKGROUND AND PURPOSE

Endovascular treatment (EVT) is a powerful treatment for large vessel occlusion (LVO) stroke if reperfusion can be achieved, while in cases with failed reperfusion, EVT may cause harm, as procedure-related complications may occur. We hypothesized that EVT with failed recanalization does not result in worse outcomes compared to best medical management and compared clinical outcomes of LVO stroke patients who underwent EVT with failed reperfusion to those who were treated with best medical management.

METHODS

We included patients with failed reperfusion from the control (EVT-only) arm of the ESCAPE-NA1 trial and the EVT arm of the ESCAPE trial and patients of the ESCAPE control arm who were treated with best medical management. Failed reperfusion following EVT was defined as modified thrombolysis in cerebral infarction score 0-2a. Proportions of good outcome (modified Rankin scale 0-2) were compared between patients who did and did not undergo EVT, and adjusted effect size estimates for EVT on outcomes were obtained.

RESULTS

We included 260 patients (110 failed EVT and 150 non-EVT patients). Proportions of good outcome were 38/110 (34.6%) with failed EVT vs.43/147 (29.3%) without EVT (adjusted odds ratio[aOR]: 1.48 [95%CI: 0.81-2.68]). Mortality and proportions of sICH in the failed EVT group vs. patients treated with best medical management were 26/110 (23.6%) vs. 28/147 (19.1%), aOR: 1.12 (95%CI: 0.56-2.24), and 7/110 (6.4%) vs. 4/150 (2.7%), aOR: 2.34 (95%CI: 0.00-22.97).

CONCLUSION

Clinical outcomes of EVT patients with failed reperfusion did not differ significantly from patients treated with best medical management.

Thrombolytic therapy for wake-up stroke: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

According to evidence-based clinical practice guidelines, patients presenting with disabling stroke symptoms should be treated with intravenous tissue plasminogen activator (IV tPA) within 4.5 h of time last known well. However, 25% of strokes are detected upon awakening (i.e., wake-up stroke [WUS]), which renders patients ineligible for IV tPA administered via time-based treatment algorithms, because it is impossible to establish a reliable time of symptom onset. We performed a systematic review and meta-analysis of the efficacy and safety of IV tPA compared with normal saline, placebo, or no treatment in patients with WUS using imaging-based treatment algorithms.

METHODS

We searched MEDLINE, Web of Science, and Scopus between January 1, 2006 and April 30, 2020. We included controlled trials (randomized or nonrandomized), observational cohort studies (prospective or retrospective), and single-arm studies in which adults with WUS were administered IV tPA after magnetic resonance imaging (MRI)- or computed tomography (CT)-based imaging. Our primary outcome was recovery at 90 days (defined as a modified Rankin Scale [mRS] score of 0-2), and our secondary outcomes were symptomatic intracranial hemorrhage (sICH) within 36 h, mortality, and other adverse effects.

RESULTS

We included 16 studies that enrolled a total of 14,017 patients. Most studies were conducted in Europe (37.5%) or North America (37.5%), and 1757 patients (12.5%) received IV tPA. All studies used MRI-based (five studies) or CT-based (10 studies) imaging selection, and one study used a combination of modalities. Sixty-one percent of patients receiving IV tPA achieved an mRS score of 0 to 2 at 90 days (95% confidence interval [CI]: 51%-70%, 12 studies), with a relative risk (RR) of 1.21 compared with patients not receiving IV tPA (95% CI: 1.01-1.46, four studies). Three percent of patients receiving IV tPA experienced sICH within 36 h (95% CI: 2.5%-4.1%; 16 studies), which is an RR of 4.00 compared with patients not receiving IV tPA (95% CI: 2.85-5.61, seven studies).

CONCLUSIONS

This systematic review and meta-analysis suggests that IV tPA is associated with a better functional outcome at 90 days despite the increased but acceptable risk of sICH. Based on these results, IV tPA should be offered as a treatment for WUS patients with favorable neuroimaging findings.

Expanding indications for endovascular thrombectomy-how to leave no patient behind

Endovascular thrombectomy (EVT) has become standard of care for large vessel occlusion strokes but current guidelines exclude a large proportion of patients from this highly effective treatment. This review therefore focuses on expanding indications for EVT in several borderline indications such as patients in the extended time window, patients with extensive signs of infarction on admission imaging, elderly patients and patients with pre-existing deficits. It also discusses the current knowledge on intravenous thrombolysis as an adjunct to EVT and EVT as primary therapy for distal vessel occlusions, for tandem occlusions, for basilar artery occlusions and in pediatric patients. We provide clear recommendations based on current guidelines and further literature.

Abstract 31: Penumbra Consumption Rates Based on T Max Delay and Reperfusion Status: A Post-Hoc Analysis of the Defuse-3 Trial

Introduction: In patients with acute large vessel occlusion, the definition of penumbral tissue based on T max delay perfusion imaging is not well established in relation to late-window endovascular thrombectomy (EVT). In this study, we sought to evaluate penumbra consumption rates for T max delays in patients treated between 6 and 16 hours from last known normal.

Methods: This is a secondary analysis of the DEFUSE-3 trial, which included patients with an acute ischemic stroke due to anterior circulation occlusion within 6-16 hours of last known normal. The primary outcome is percentage penumbra consumption defined as (24 hour infarct volume-core infarct volume)/(Tmax volume-baseline core volume). We stratified the cohort into 4 categories (untreated, TICI 0-2a, TICI 2b, and TICI3) and calculated penumbral consumption rates.

Results: We included 143 patients, of which 66 were untreated, 16 had TICI 0-2a, 46 had TICI 2b, and 15 had TICI 3. In untreated patients, a median (IQR) of 48% (21% - 85%) of penumbral tissue was consumed based on Tmax6 as opposed to 160.6% (51% - 455.2%) of penumbral tissue based on Tmax10. On the contrary, in patients achieving TICI 3 reperfusion, a median (IQR) of 5.3% (1.1% - 14.6%) of penumbral tissue was consumed based on Tmax6 and 25.7% (3.2% - 72.1%) of penumbral tissue based on Tmax10.

Conclusion: Contrary to prior studies, we show that at least 75% of penumbral tissue with Tmax > 10 sec delay can be salvaged with successful reperfusion and new generation devices. In untreated patients, since infarct expansion can occur beyond 24 hours, future studies with delayed brain imaging are needed to determine the optimal T max delay threshold that defines penumbral tissue in patients with proximal anterior circulation large vessel occlusion.

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 1: Thrombolytic Therapy for ‘Wake-Up Stroke’ - A Systematic Review and Meta-Analysis

Introduction: Twenty-five percent of strokes are detected upon awakening (‘wake-up strokes’; WUS) and are not amenable to thrombolytic therapy via existing time-based treatment approaches. We performed a systematic review and meta-analysis of the efficacy and safety of thrombolysis in patients with WUS using imaging-based selection algorithms.

Methods: This systematic review was registered through PROSPERO (CRD42020151552). We searched PubMed, Web of Science, and Scopus between January 1, 2006 and April 30, 2020 for controlled trials and observational cohort studies (prospective or retrospective), in which adults with WUS were administered thrombolysis after MR- or CT-based imaging. Our primary outcome was recovery (mRS 0-2) at 90 days and our secondary outcome was symptomatic intracranial hemorrhage (sICH). We assessed risk of bias using the Cochrane Risk of Bias 2.0 and ROBINS-I tools.

Results: We included 16 studies that enrolled a total of 14,017 patients. Sixty-one percent of patients receiving tPA achieved a functional recovery at 90 days (95% CI: 51% to 70%; 12 studies), with a relative risk (RR) of recovery of 1.21 compared with patients not receiving tPA (95% CI 1.01 to 1.46; 4 comparative studies). As shown in Figure 1, 3% of patients receiving tPA in the treated WUS stroke group experienced sICH, an RR of 4.0 (95% CI 2.85-5.61) compared with patients not receiving tPA. On meta-regression, advancing age was negatively associated with the RR of recovery (p<0.001) and there was a trend that increased NIHSS was associated with the RR of sICH (p=0.083).

Conclusions: In patients with WUS, thrombolysis is associated with functional recovery and with a low risk of sICH. This risk is comparable to the sICH rate from tPA-treatment of stroke utilizing the standard protocol timeframe (2.4% in ECASS III). Thrombolysis should be considered in the treatment of WUS in patients with favorable neuroimaging.

Clinical outcomes of isolated deep grey matter infarcts after endovascular treatment of large vessel occlusion stroke

PURPOSE

There are few data on the prevalence and impact of isolated deep grey matter infarction in acute stroke. In this study, we aimed to investigate the prevalence of isolated deep grey matter infarcts and their impact on the outcome.

METHODS

Infarcts on 24-h follow-up imaging (non-contrast head CT or diffusion-weighted MRI) in the ESCAPE-NA1 trial were categorized into predominantly deep grey matter infarcts vs. infarcts involving additional territories ("other infarcts"). Total infarct volume was manually segmented. Baseline characteristics and proportions of good outcome (primary outcome, defined as modified Rankin Score [mRS] 0-2 at 90 days), excellent outcome (mRS 0-1) and mortality were compared between patients with and without predominantly deep grey matter infarcts. Multivariable logistic regression with adjustment for baseline variables and total infarct volume was used to determine a possible association of predominantly deep grey matter infarcts and clinical outcome.

RESULTS

Predominantly deep grey matter infarcts were seen in 316/1026 patients (30.8%). Compared to other patients, their ASPECTS was higher, collateral status and reperfusion quality were better and time to treatment was shorter. Good outcome was seen in 239/316 (75.6%) with vs. 374/704 (53.1%) without predominantly deep grey matter infarcts. After adjusting for baseline variables and total infarct volume, predominantly deep grey matter infarcts were independently associated with excellent outcome (_adjOR: 1.45 [CI₉₅: 1.04-2.02]), but not with good outcome (_adjOR: 1.24 [CI₉₅: 0.86-1.80]) or mortality (_adjOR: 0.73 [CI₉₅:0.39-1.35]) CONCLUSION: Predominantly deep grey matter infarct patterns were seen in 1/3rd of patients and were significantly associated with increased chances of excellent outcome, independent of patient baseline status and infarct size.

Challenging the Ischemic Core Concept in Acute Ischemic Stroke Imaging

Endovascular treatment is a highly effective therapy for acute ischemic stroke due to large vessel occlusion and has recently revolutionized stroke care. Oftentimes, ischemic core extent on baseline imaging is used to determine endovascular treatment-eligibility. There are, however, 3 fundamental issues with the core concept: First, computed tomography and magnetic resonance imaging, which are mostly used in the acute stroke setting, are not able to precisely determine whether and to what extent brain tissue is infarcted (core) or still viable, due to variability in tissue vulnerability, the phenomenon of selective neuronal loss and lack of a reliable gold standard. Second, treatment decision-making in acute stroke is multifactorial, and as such, the relative importance of single variables, including imaging factors, is reduced. Third, there are often discrepancies between core volume and clinical outcome. This review will address the uncertainty in terminology and proposes a direction towards more clarity. This theoretical exercise needs empirical data that clarify the definitions further and prove its value.

Mechanical Thrombectomy in Ischemic Stroke Patients with Severe Pre-Stroke Disability

Frequency and outcomes of mechanical thrombectomy (MT) in clinical practice for patients with severe pre-stroke disability are largely unknown. In this case series, we aim to describe the disability make-up and outcomes of 33 patients with severe pre-stroke disability undergoing MT. Patients with a permanent, severe, pre-stroke disability (modified Rankin Score, mRS, 4-5) were identified from a prospectively-maintained database of consecutive, MT-treated, anterior circulation acute ischemic stroke patients at two comprehensive stroke centers in the United States. We present details on the cause of disability and socio-demographic status as well as procedural and functional outcomes. This study, despite the lack of inferential testing due to limited sample size, provides insight into demographics and outcomes of MT-treated patients with severe pre-stroke disability. Rate of return to functional baseline as well as rates of procedural success and complications were comparable to that reported in the literature for patients without any pre-existing disability.

Evolution of Stroke Thrombectomy Techniques to Optimize First-Pass Complete Reperfusion

Since 2015, endovascular therapy (EVT) has become the standard of care for acute ischemic stroke (AIS) due to large vessel occlusion. It is a safe and highly effective treatment, and its number needed to treat of 2.6 is one of the highest throughout medicine. The ultimate goal when performing EVT is to maximize chances of good outcome through achievement of fast first-pass complete reperfusion, as incomplete and delayed reperfusion increases complication rates and negatively affects outcome. Since EVT has been established as standard of care, new devices have been developed and treatment techniques have been refined. This review provides a brief overview about the rationale for and history of EVT, followed by a detailed step-by-step description of how to perform EVT using the BADDASS (BAlloon guide with large bore Distal access catheter with Dual Aspiration with Stent-retriever as Standard approach), a combined technique, which is in our opinion the safest and most effective way to achieve fast first-pass complete reperfusion. We also discuss treatment strategies for patients with simultaneous high-grade carotid stenosis/pseudoocclusion/occlusion and gaining carotid access in challenging arch anatomy, as these are commonly encountered situations in AIS, and conclude with an outlook on new technologies and future directions of EVT.

Mechanical Thrombectomy in Patients With Ischemic Stroke With Prestroke Disability

Background and Purpose- We aimed to compare functional and procedural outcomes of patients with acute ischemic stroke with none-to-minimal (modified Rankin Scale [mRS] score, 0-1) and moderate (mRS score, 2-3) prestroke disability treated with mechanical thrombectomy. Methods- Consecutive adult patients undergoing mechanical thrombectomy for an anterior circulation stroke were prospectively identified at 2 comprehensive stroke centers from 2012 to 2018. Procedural and 90-day functional outcomes were compared among patients with prestroke mRS scores 0 to 1 and 2 to 3 using χ2, logistic, and linear regression tests. Primary outcome and significant differences in secondary outcomes were adjusted for prespecified covariates. Results- Of 919 patients treated with mechanical thrombectomy, 761 were included and 259 (34%) patients had moderate prestroke disability. Ninety-day mRS score 0 to 1 or no worsening of prestroke mRS was observed in 36.7% and 26.7% of patients with no-to-minimal and moderate prestroke disability, respectively (odds ratio, 0.63 [0.45-0.88], P=0.008; adjusted odds ratio, 0.90 [0.60-1.35], P=0.6). No increase in the disability at 90 days was observed in 22.4% and 26.7%, respectively. Rate of symptomatic intracerebral hemorrhage (7.3% versus 6.2%, P=0.65), successful recanalization (86.7% versus 83.8%, P=0.33), and median length of hospital stay (5 versus 5 days, P=0.06) were not significantly different. Death by 90 days was higher in patients with moderate prestroke disability (14.3% versus 40.3%; odds ratio, 4.06 [2.82-5.86], P<0.001; adjusted odds ratio, 2.83 [1.84, 4.37], P<0.001). Conclusions- One-third of patients undergoing mechanical thrombectomy had a moderate prestroke disability. There was insufficient evidence that functional and procedural outcomes were different between patients with no-to-minimal and moderate prestroke disability. Patients with prestroke disability were more likely to die by 90 days.

Recanalization following Endovascular treatment and imaging of PErfusion, Regional inFarction and atrophy to Understand Stroke Evolution-NA1 (REPERFUSE-NA1)

RATIONALE

Following endovascular treatment, poor clinical outcomes are more frequent if the initial infarct core or volume of irreversible brain damage is large. Clinical outcomes may be improved using neuroprotective agents that reduce stroke volume and improve recovery.

AIM

The aim of the REPERFUSE NA1 was to replicate the preclinical neuroprotection study that significantly reduced infarct volume in a primate model of ischemia reperfusion. Specifically, REPERFUSE NA1 will determine if administration of the neuroprotectant NA1 prior to endovascular therapy can significantly reduce early (Day 2 subtract Day 1 diffusion-weighted imaging volume) and delayed secondary infarct (90-day whole brain atrophy plus FLAIR volume-Day 1 diffusion-weighted imaging volume) growth, as measured by magnetic resonance imaging.

METHODS AND DESIGN

REPERFUSE-NA1 is a magnetic resonance imaging observational substudy of ESCAPE-NA1 (ClinicalTrialGov NCT02930018). A total of 150 acute stroke patients will be recruited (including 20% attrition) that have been randomized to either NA1 or placebo in the ESCAPE-NA1 trial.

STUDY OUTCOMES

Primary-Early infarct growth measured using diffusion-weighted imaging will be at least 30% smaller in patients receiving NA1 compared to placebo. Secondary-Delayed secondary stroke injury at 90 days will be significantly reduced in patients receiving NA1 compared to placebo, as well as delayed secondary growth at 90 days.

CONCLUSION

REPERFUSE-NA1 will demonstrate the effect of NA1 neuroprotection on reducing the early and delayed stroke injury after reperfusion treatment.

Abstract 116: Predicting Symptomatic Intracranial Hemorrhage After Mechanical Thrombectomy: The TAG Score

Background: There is limited data on predictors of sICH in patients who underwent mechanical thrombectomy. In this study, we aim to determine those predictors with external validation.

Methods: We evaluated mechanical thrombectomy in a derivation cohort of patients at a comprehensive stroke center over a 30-month period. sICH was defined using the European Cooperative Acute Stroke Study III. We compared clinical and radiographic characteristics between patients with and without sICH to identify independent predictors of sICH with p<0.1. We then derived an sICH prediction score and validated it using the Blood Pressure After Endovascular Treatment (BEST) multicenter prospective registry.

Results: We identified 578 patients with acute ischemic stroke who received thrombectomy, 19 had sICH (3.3%). Predictive factors of sICH were: Thrombolysis in cerebral ischemia score, Alberta stroke program early computed tomography score (ASPECTS), and Glucose level, and using these predictors, we derived the weighted TAG score which was associated with sICH in the derivation (OR per unit increase 1.98, 95% CI 1.48-2.66, AUC=0.79) and validation (OR per unit increase 1.48, 95% CI 1.22-1.79, AUC=0.69) cohorts.

Conclusion: High TAG scores are associated with sICH in patients receiving mechanical thrombectomy. Larger studies are needed to validate this scoring system and test strategies to reduce sICH risk and make thrombectomy safer in patients with elevated TAG scores.

Abstract WP109: Redefining Early Neurological Improvement After Intravenous Tissue Plasminogen Activator Treatment of Stroke

Background and Purpose: Early neurologic improvement (ENI) in patients treated with alteplase has been shown to correlate with functional outcome. However, the definition of ENI remains controversial and has varied across studies. Current definitions take into account the absolute difference between the admission and 24-hour NIHSS but this difference is usually not reported as a function of the baseline NIHSS. We hypothesized that ENI defined as a percentage change in NIHSS (percent change NIHSS) at 24-hours would better correlate with favorable outcomes at 3 months than ENI defined as the change in NIHSS (delta NIHSS) at 24 hours.

Methods: Retrospective analysis of prospectively collected single center quality improvement data was performed of all acute ischemic stroke (AIS) patients treated with alteplase. Delta NIHSS was defined as the difference in admission and 24-hour NIHSS. Percent change NIHSS was defined as delta NIHSS divided by the admission NIHSS. We examined delta NIHSS and percent change NIHSS in unadjusted and adjusted logistic regression models as predictors of a favorable outcome at 3 months (defined as mRS 0-1).

Results: Among 586 patients with AIS treated with alteplase with admission NIHSS, 24-hour NIHSS, and 3-month mRS available, 194 (33.1%) had a favorable outcome at 3 months. The mean age was 65 years and 59% were men. In fully adjusted models, both delta NIHSS (OR per point decrease 1.27; 95% CI, 1.19– 1.36) and percent change NIHSS (OR per 10 percent decrease 1.17; 95% CI, 1.12-1.22) were associated with favorable functional outcome at 3 months. Receiver operating characteristic (ROC) curve comparison showed that the area under the ROC curve for percent change NIHSS (0.755) was greater than delta NIHSS (0.613) or admission NIHSS (0.694).

Conclusion: Percentage change in NIHSS may be a better surrogate marker of ENI and functional outcome in AIS patients after receiving acute thrombolytic therapy. More studies are needed to confirm our findings.

Abstract WP254: Insular Involvement of Ischemic Stroke Suggests a Cardioembolic Mechanism

Introduction: The insular cortex controls several aspects of vital function including autonomic regulation, and strokes affecting the insula have been associated with dysautonomia, cardiac dysfunction, and arrhythmias. Previous studies have shown an association between insular strokes, elevated troponin levels, and atrial fibrillation (AF). In this study, we aim to determine the association between cardiac biomarkers and insular involvement of the infarct and hypothesize that insular involvement implicates a cardioembolic source.

Methods: We abstracted data from a prospective comprehensive stroke center registry of consecutive patients with a discharge diagnosis of acute ischemic stroke who underwent brain imaging (CT or MRI) and work up to determine stroke mechanism. Data included demographics, clinical baseline variables, laboratory tests (including admission troponin level), and transthoracic echocardiographic variables (regional wall motion abnormalities, ejection fraction, and left atrial volume index), and stroke subtype. Multivariable logistic regression models were built to determine associations between AF, and cardiac biomarkers and insular infarcts.

Results: We identified 1224 patients who met the inclusion criteria; 397 (32.4%) had insular involvement of the infarct. In multivariable models, insular infarcts were associated with AF (adjusted OR 1.73, 95% CI 1.23-2.43, p = 0.001) and left atrial volume index (adjusted OR per standard deviation increase 1.30, 95% CI 1.13-1.49, p = 0.001). There was a trend for association between insular involvement and positive troponin level (adjusted OR 1.45 95% CI 0.91-2.33, p = 0.122) but not with regional wall motion abnormalities (adjusted OR 1.13, 95% CI 0.69-1.84, p = 0.627). Insular involvement was associated with cardioembolic stroke subtype (45.8% vs. 26.7%, p<0.001) but not other stroke subtypes.

Conclusion: The insular cortex is commonly involved in patients with atrial fibrillation and/or atrial dilation and maybe a neuroimaging biomarker of cardioembolic stroke. Larger studies are needed to confirm this association and test anticoagulation therapy in patients with insular infarcts.

Abstract 166: Mechanical Thrombectomy in Ischemic Stroke Patients With Pre-Stroke Disability

Background: The current AHA/ASA guidelines recommend only offering mechanical thrombectomy (MT) to patients without pre-stroke disability. We aimed to compare outcomes of acute ischemic stroke patients with none-to-minimal (modified Rankin score, mRS, 0-1) and moderate (mRS 2-3) pre-stroke disability treated with MT.

Methods: Consecutive adult patients undergoing MT for an anterior circulation stroke were prospectively identified at two comprehensive stroke centers from 2012-2018. Procedural and 90-day functional outcomes were compared among patients with pre-stroke mRS 0-1 and 2-3 using Chi-squared, logistic, and linear regression tests and were adjusted for prespecified covariates.

Results: A total of 881 patients were included (mean age 70±16 years; 45% female) and 259 (29.4%) had moderate pre-stroke disability. Primary outcome of no accumulation of additional disability at 90 days was observed in 22.4% and 26.7% of patients with no-to-minimal and moderate pre-stroke disability, respectively (OR 1.27[0.88-1.81], p=0.2; adjusted OR 1.90[1.24, 2.94], p=0.004, Figure). Rate of symptomatic intracerebral hemorrhage (7.3% vs 6.2%, p=0.65), successful recanalization (86.7% vs 83.8%, p=0.33), and median length of hospital stay (5 vs 5 days, p=0.06) were not significantly different. Mean change in utility weighted mRS from baseline to 90 days was 0.35±0.35 in pre-stroke mRS 0-1 vs -0.38 ±0.32 in pre-stroke mRS 2-3, p=0.17. Death by 90-days was higher in patients with moderate pre-stroke disability (14.3% vs 40.3%, OR 4.06[2.82-5.86], p<0.001; adjusted OR 2.83[1.84, 4.37], p<0.001).

Interpretation: One-third of patients undergoing MT had a moderate pre-stroke disability. The odds of maintaining pre-stroke functional status at 90-days and procedural success rates were not different between patients with no-to-minimal and moderate pre-stroke disability. However, patients with pre-stroke disability were more likely to die by 90 days.

Abstract TP122: Peri-Procedural Stroke or Death in Stenting of Symptomatic Severe Intracranial Stenosis: A Post-Hoc Analysis of the SAMMPRIS Trial

Background and Purpose: There is limited data on predictors of 30-day stroke or death in patients with symptomatic intracranial atherosclerosis (sICAS) undergoing stenting. We aim to determine these predictors.

Methods: This is a post-hoc analysis SAMMPRIS including patients who underwent angioplasty/stenting. We determined associations between patient-specific, lesion-specific, and procedure-specific variables, and FDA-approved indications and the primary outcome (stroke or death at 30 days) using logistic regression analyses.

Results: We identified 213 patients; 30 patients (14.1%) met the primary outcome. The odds of stroke or death was higher with non-smokers vs. smokers (adjusted OR 4.46, 95% CI 1.79-11.1) and increasing lesion length in millimeters (adjusted OR 1.20, 95% CI 1.02-1.39). These had modest predictive value: absence of smoking history (sensitivity=66.7% and specificity=65.4%) and lesion length (Area Under Curve=0.606). Furthermore, event rates were not significantly different between patients with and without the FDA approved indication for stenting (15.9% vs. 12%, p = 0.437).

Conclusion: In SAMMPRIS patients who underwent angioplasty/stenting, neither clinical and neuroimaging variables nor the FDA indication for stenting reliably predicted the primary outcome. Further work in identifying reliable biomarkers of stroke/death in patients with sICAS is needed before considering new clinical trials of stenting.

Abstract TP341: Yield of Interval Magnetic Resonance Imaging in Determining Cryptogenic Etiologies of Spontaneous Intracerebral Hemorrhage

Introduction: Spontaneous intracerebral hemorrhage (ICH) most commonly arises due to primary etiologies such as hypertensive or cerebral amyloid angiopathy (CAA), but may also occur due to underlying secondary causes such as vascular malformations or intracranial neoplasms. However, focal mass effect may potentially obscure underlying lesions on neuroimaging performed during the acute phase of ICH, and follow-up imaging is often recommended. We sought to determine the yield of interval magnetic resonance imaging (MRI) in identifying cryptogenic ICH etiologies.

Methods: We performed a single-center descriptive cohort study of consecutive patients enrolled in an institutional ICH registry over 12 months. ICH features including etiology and acute neuroimaging were prospectively adjudicated, while planned interval follow-up imaging was retrospectively reviewed. We determined the frequency of newly-discovered findings on interval MRI, and classified new findings according to whether or not they contributed meaningfully to patient management.

Results: There were 241 ICH patients in our cohort who survived to discharge and did not have MRI-incompatible devices; 44 had planned follow-up imaging and 33 ultimately completed a follow-up MRI. Mean interval between initial and follow-up MRI was 61 (±34) days. New findings were identified in 33% of follow-up cases (11/33), with changes in patient management occurring in 12% (4/33). Age (59.4 vs. 61.5, p=0.74), sex (45% vs. 45% male, p>0.99), and secondary ICH score (median 3 [IQR 2-3] vs. 3 [1-4], p=0.87) were not significantly different between patients who had new findings and those who did not. New findings included cavernoma (n=4; 1 underwent resection), CAA-related changes (n=3), intracranial malignancy (n=2; 1 transitioned to hospice care, 1 led to cancer workup), new embolic stroke (n=1, underwent extended cardiac monitoring), and demyelination (n=1).

Conclusions: Interval MRI aided in diagnosing ICH etiology in one-third of patients who received one, though few cases led to direct actionable changes in patient management.

Abstract TP222: Prevalence of Carotid Web in Patients With Cryptogenic Stroke

Introduction: Carotid web is a putative mechanism of cryptogenic ischemic stroke. We aimed to determine the prevalence of carotid web based on assigned stroke mechanism, and hypothesized that carotid webs would be found more frequently in younger cryptogenic stroke patients.

Methods: We performed a single-center retrospective cohort study using institutional registry data from consecutive patients with confirmed anterior circulation ischemic stroke between July 2015-September 2017. We reviewed all available computed tomography angiogram (CTA) studies of the neck, and excluded patients who did not have a high-quality CTA of the neck performed. Carotid web was defined as a thin shelf of non-calcified tissue protruding into the lumen of the internal carotid artery immediately distal to the bifurcation, best visualized on sagittal oblique imaging and evident as a small septum on axial imaging. Stroke subtype was adjudicated a priori using validated methods, and we compared relevant risk factors in patients with cryptogenic stroke with and without carotid web.

Results: We identified 882 patients with anterior circulation stroke who had a CTA neck available for review (49.3% male, 30% cryptogenic). A total of 7 patients (0.8%) were found to have carotid webs, of which 4 were ipsilateral to a patient’s stroke; all patients with ipsilateral carotid webs were adjudicated to have cryptogenic stroke. Patients with carotid web were younger than other patients in our cohort (age 49.0±14.6 vs. 72.2±14.9 years, p=0.003), and none of them had a history of hypertension (0% vs. 72%, p=0.04). In patients with cryptogenic stroke, overall prevalence of carotid webs was 1.5%, but the prevalence was significantly higher in younger cryptogenic stroke patients (age <60: 4.8%; age ≥60: 0.5%; p=0.01). Imaging findings that mimicked carotid webs, including non-calcified atherosclerosis and small protruding lesions, were prevalent in 8.3% of all patients.

Discussion: Carotid web may represent an under-recognized occult mechanism of cryptogenic stroke, particularly amongst younger patients.

Abstract WP128: Stroke Subtype Predicts Neurological Deterioration After Intravenous Alteplase for Acute Ischemic Stroke

Introduction: Intravenous alteplase improves functional outcome in patients with acute ischemic stroke. While patients often have better outcomes, other patients may experience recurrent or worsening symptoms. We sought to determine the association between stroke subtype and neurologic deterioration in this study cohort.

Methods: Data were abstracted from a prospective quality improvement registry at a comprehensive stroke center. Patients with symptomatic intracranial hemorrhage, no follow-up imaging, code status change to comfort measures only in the first 24 hours, or stroke mimics were excluded. Recurrent cerebrovascular events (RCVE) were defined as any new or worsening symptoms due to cerebral ischemia in the absence of intracranial hemorrhage or an alternative etiology such as infection or seizure. We compared demographic factors, vascular comorbidities, admission blood pressure, medications, use and timing of antithrombotics during hospitalization, admission NIH stroke scale, endovascular intervention, stroke subtype [Cardioembolic, large artery atherosclerosis, small vessel disease, cryptogenic, and other defined (such as dissection, hypercoagulability, cancer related, illicit drug use)], and good 90-day outcome (mRS 0-1) between the two groups using Fisher’s exact test and t-test as indicated. We then performed multivariable logistic regression analyses to determine associations between stroke subtypes and RCVE.

Results: We identified 705 patients treated with tPA, and 606 met the inclusion criteria. The rate of RCVE was 5.8% (35/606). In multivariable analyses, when compared to cardioembolic/cryptogenic stroke, RCVE was more common in small vessel disease (adjusted OR 9.51 p=0.029), large vessel disease (adjusted OR 5.60, p=0.033), and other stroke mechanisms (adjusted OR 11.29, p=0.019). RCVE was associated with more disability at 90 days when compared to non-RCVE (median mRS 4, IQR 3 vs. median mRS 3, IQR 2, p = 0.016).

Conclusions: Non-cryptogenic/Non-cardioembolic stroke subtypes are associated with early RCVE, and RCVE is associated with long term disability. Studies are needed to confirm our findings and test interventions optimizing stroke prevention strategies in these subtypes.

Predicting symptomatic intracranial haemorrhage after mechanical thrombectomy: the TAG score

BACKGROUND

There is limited data on predictors of symptomatic intracranial haemorrhage (sICH) in patients who underwent mechanical thrombectomy. In this study, we aim to determine those predictors with external validation.

METHODS

We evaluated mechanical thrombectomy in a derivation cohort of patients at a comprehensive stroke centre over a 30-month period. Clinical and radiographic data on these patients were obtained from the prospective quality improvement database. sICH was defined using the European Cooperative Acute Stroke Study III. We compared clinical and radiographic characteristics between patients with and without sICH using χ² and t tests to identify independent predictors of sICH with p<0.1. Significant variables were then combined in a multivariate logistic regression model to derive an sICH prediction score. This score was then validated using data from the Blood Pressure After Endovascular Treatment multicentre prospective registry.

RESULTS

We identified 578 patients with acute ischaemic stroke who received thrombectomy, 19 had sICH (3.3%). Predictive factors of sICH were: thrombolysis in cerebral ischaemia (TICI) score, Alberta stroke program early CT score (ASPECTS), and glucose level, and from these predictors, we derived the weighted TICI-ASPECTS-glucose (TAG) score, which was associated with sICH in the derivation (OR per unit increase 1.98, 95% CI 1.48 to 2.66, p<0.001, area under curve ((AUC)=0.79) and validation (OR per unit increase 1.48, 95% CI 1.22 to 1.79, p<0.001, AUC=0.69) cohorts.

CONCLUSION

High TAG scores are associated with sICH in patients receiving mechanical thrombectomy. Larger studies are needed to validate this scoring system and test strategies to reduce sICH risk and make thrombectomy safer in patients with elevated TAG scores.

Echocardiographic wall motion abnormalities in patients with stroke may warrant cardiac evaluation

Background

The aetiology of wall motion abnormalities (WMA) in patients with ischaemic stroke is unclear. We hypothesised that WMAs on transthoracic echocardiography (TTE) in the setting of ischaemic stroke mostly reflect pre-existing coronary heart disease rather than simply an isolated neurocardiogenic phenomenon.

Methods

Data were retrospectively abstracted from a prospective ischaemic stroke database over 18 months and included patients with ischaemic stroke who underwent a TTE. Coronary artery disease was defined as history of myocardial infarction (MI), coronary intervention or ECG evidence of prior MI. The presence (vs absence) of WMA was abstracted. Multivariable logistic regression was used to determine the association between coronary artery disease and WMA in models adjusting for potential confounders.

Results

We identified 1044 patients who met inclusion criteria; 139 (13.3%, 95% CI 11.2% to 15.4%) had evidence of WMA of whom only 23 (16.6%, 95% CI 10.4% to 22.8%) had no history of heart disease or ECG evidence of prior MI. Among these 23 patients, 12 had a follow-up TTE after the stroke and WMA persisted in 92.7% (11/12) of patients. In fully adjusted models, factors associated with WMA were older age (OR per year increase 1.03, 95% 1.01 to 1.05, p=0.009), congestive heart failure (OR 4.44, 95% CI 2.39 to 8.33, p<0.001), history of coronary heart disease or ECG evidence prior MI (OR 27.03, 95% CI 14.93 to 50.0, p<0.001) and elevated serum troponin levels (OR 2.00, 95% CI 1.06 to 3.75, p=0.031).

Conclusion

In patients with ischaemic stroke, WMA on TTE may reflect underlying cardiac disease and further cardiac evaluation may be considered.

Clot reduction prior to embolectomy: mSAVE as a first-line technique for large clots

Introduction

The “Stent retriever Assisted Vacuum-locked Extraction” (SAVE) technique is a promising embolectomy method for intracranial large vessel occlusion (LVO). We report our experience using a modified SAVE (mSAVE) approach for clot reduction prior to embolectomy in acute ischemic stroke patients with large clots.

Materials and methods

We retrospectively analyzed 20 consecutive patients undergoing mSAVE in our center due to intracranial LVO. Angiographic data (including first-pass and overall complete reperfusion, defined as an expanded Thrombolysis in Cerebral Infarction (eTICI) score of 3, rate of successful reperfusion (eTICI ≥2c), number of passes, time from groin puncture to reperfusion) and clinical data (favorable outcome at 90 days, defined as modified Rankin Scale (mRS) ≤2) were assessed.

Results

First-pass and overall eTICI 3 reperfusion was reached in 13/20 (65%) and 14/20 (70%), respectively. The rate of successful reperfusion (eTICI ≥2c) after one pass was 85% and on final angiogram 90% with an average number of 1.1 ± 0.3 attempts. Eight out of 11 (73%) ICA occlusions were reperfused successfully and 5 (46%) completely after a single pass. Median groin to reperfusion time was 33 minutes (IQR 25–46). A favorable clinical outcome was achieved in 9/20 (45%) patients at discharge and after 90 days, respectively.

Conclusion

Clot reduction followed by embolectomy (mSAVE) is feasible and may be an important tool in the treatment of large clots.

The left atrial appendage morphology is associated with embolic stroke subtypes using a simple classification system: A proof of concept study

BACKGROUND AND PURPOSE

The current left atrial appendage (LAA) classification system (cLAA-CS) categorizes it into 4 morphologies: chicken wing (CW), windsock, cactus, and cauliflower, though there is limited data on either reliability or associations between different morphologies and stroke risk. We aimed to develop a simplified LAA classification system and to determine its relationship to embolic stroke subtypes.

METHODS

Consecutive patients with ischemic stroke from a prospective stroke registry who previously underwent a clinically-indicated chest CT were included. Stroke subtype was determined and LAA morphology was classified using the traditional system (in which CW = low risk) and a new system (LAA-H/L, in which low risk morphology (LAA-L) was defined as an acute angle bend or fold from the proximal/middle portion of the LAA and high risk morphology (LAA-H) was defined as all others). As a proof of concept study, we determined reliability for the two classification systems, and we assessed the associations between both classification systems with stroke subtypes in our cohort and previous studies.

RESULTS

We identified 329 ischemic stroke patients with a qualifying chest CT (126 cardioembolic subtype, 116 embolic stroke of undetermined source (ESUS), and 87 non-cardioembolic subtypes). Intra- and inter-rater agreements improved using the LAA-H/L (0.95 and 0.85, respectively) vs. cLAA-CS (0.50 and 0.40). The LAA-H/L led to classifying 69 LAA morphologies that met criteria for CW as LAA-H. In fully adjusted models, LAA-H was associated with cardioembolic stroke (OR 5.4, 95%CI 2.1-13.7) and ESUS (OR 2.8 95% CI 1.2-6.4). Non-CW morphology was also associated with embolic stroke subtypes, but the effect size was much less pronounced. Studies using the cLAA-CS yielded mixed results for inter- and intra-rater agreements but most showed an association between a non-CW morphology and stroke with no difference among the three non-CW subtypes.

CONCLUSION

The LAA-H/L classification system is simple, has excellent intra and inter-rater agreements, and may help risk identify patients with cardioembolic stroke subtypes. Larger studies are needed to validate these findings.

Abstract TP77: Collateral- vs Perfusion-Based Selection Paradigm of Late Window (6-24 hours) Patients With Acute Ischemic Stroke a Comparative Study of Decision Making Using Multi-Phase CTA and CT Perfusion

Purpose: To compare the performance of collateral- vs perfusion-based imaging paradigms in late window stroke patients.

Methods: In the prospective international (PRove-IT) study, patients had baseline CT head, multi-phase CTA (mCTA) and CTP. Patients presenting 6-24 hours of onset were included. We retrospectively selected patients for EVT based on 1) Collaterals: ASPECTS ≥5, plus proximal intracranial occlusion, plus good mCTA collaterals; 2) Perfusion: using DEFUSE-3, or DAWN trial criteria. CTP was processed using RAPID software. The performance of each paradigm to predict outcomes was assessed using the area under the receiver operating characteristic curve (AUC) of logistic regression models adjusting for age, NIHSS, sex, onset to CT time, EVT treatment, and interaction of EVT and the imaging paradigm.

Results: We included 83 patients; medians of age 71, NIHSS 12, ASPECTS 9, and onset/ last seen well to CT of 576 minutes. Occlusions were: ICA, M1, M2-MCA (81.9 %), distal (8.4%) and none (9.6%). 35 patients received EVT (all without IV tPA), 10 IV tPA, and 38 treated conservatively. TICI 2b-3 was achieved in 71.4% of EVT patients. mRS≤2 at 90 days was achieved in 47% (51.4% with EVT: 72% of TICI2b/3 patients). Table 1 shows 90-day mRS according to the imaging paradigm for the entire cohort. Among 10 patients who were EVT-eligible according to mCTA but not DEFUSE-3, 70% achieved mRS≤2. Among 31 who were EVT-eligible per mCTA but not DAWN, 61% achieved mRS≤2. For 5 patients who were EVT-eligible per DEFUSE-3 but not mCTA, 60% achieved mRS≤2. No patients were EVT-eligible per DAWN but not per mCTA. All paradigms had comparable AUCs for 90-day mRS≤2. In the EVT subgroup, mCTA had AUC of 0.80 vs 0.79 for DAWN, and 0.78 in DEFUSE-3 paradigms.

Conclusion: The mCTA-defined collateral paradigm performs similarly well for EVT selection in the late time window. It also may include additional patients with possible benefit from ECT who would have been excluded by CTP-based imaging selection.

Abstract WP263: Wall Motion Abnormalities on Transthoracic Echocardiography in the Setting of Ischemic Stroke Reflect Underlying Cardiac Disease and May Warrant an Ischemic Cardiac Evaluation

Background and Purpose: Patients with acute ischemic stroke (AIS) are at a heightened risk of cardiovascular events. We hypothesize that wall motion abnormalities (WMA) on transthoracic echocardiography (TTE) in the setting of AIS reflect underlying heart disease rather than reversible cardiac strain caused by the stroke.

Methods: Data was abstracted from a single center prospective AIS database over 18 months and included all patients with acute ischemic stroke who underwent a TTE. The presence of WMA was abstracted from the TTE report. Univariate analyses and predefined multivariable models were performed to determine factors associated with WMA, including demographic factors (age and sex), risk factors (hypertension, diabetes, hyperlipidemia, history of stroke, atrial fibrillation, congestive heart failure, coronary heart disease, and smoking), NIHSS score, cardiac markers (positive troponin, ECG evidence of prior myocardial infarction, ejection fraction), and insular location of infarct.

Results: We identified 1044 patients who met the inclusion criteria; 139 (13.3%) had evidence of WMA, of which only 23 patients had no history of heart disease or ECG evidence of prior myocardial infarction. Among these 23 patients, 12 had a follow up TTE after the stroke and WMA persisted in 92.7% (11/12) of patients. On fully adjusted models, factors associated with WMA are older age (OR per SD 1.03, 95% CI 1.001-1.05; p=0.009), congestive heart failure (OR 4.44, 95% CI 2.39-8.33, p<0.001), history of coronary artery disease or ECG evidence prior myocardial infarction (OR 27.03, 95% CI 14.93-50.0, p<0.001), and elevated serum troponin levels (OR 2.00, 95% CI 1.06-3.75, p=0.031).

Conclusion: In AIS patients, WMA on TTE may reflect underlying cardiac disease and warrant further cardiovascular evaluation particularly in those without known history of cardiac disease. Future studies are needed to investigate the cost-effectiveness of this approach.

Abstract TP98: Diabetes Mellitus Predicts Symptomatic Intracerebral Hemorrhage Following Thrombectomy in Acute Ischemic Stroke

Introduction: Diabetes mellitus has deleterious effects on blood vessel integrity via several mechanisms including blood brain barrier injury, excitatory chemokines, acidosis, and edema. It has been associated with symptomatic intracerebral hemorrhage (sICH) after alteplase administration for ischemic stroke. We aim to determine the association between diabetes and sICH in patients undergoing thrombectomy.

Methods: Data was abstracted from the Rhode Island Hospital prospective stroke registry and included consecutive patients who were selected for thrombectomy at our institution over a period of 24 months with the goal of identifying risk factors for sICH. The primary predictor was history of diabetes and the primary outcome was sICH defined based on the modified SITS-MOST criteria (parenchymal hematoma along with increase in NIHSS by 4 points or more). We compared baseline characteristics between patients with and without sICH using univariate and multivariable analyses. Statistical analysis was performed using SPSS version 20.0 and a p value of <0.05 was statistically significant.

Results: Out of 307 patients, 12 (3.9%) experienced sICH. The mean age was 73 years; 49.2% were men. On univariate analyses, diabetes mellitus was associated with sICH (50.0% vs. 17.3%, p= 0.012). This association persisted on multivariable models adjusting for age, NIHSS score, ASPECTS score, time to reperfusion, and TICI score (Odds Ratio 6.0, 95% CI 1.5-23.3, p=0.011). We performed sensitivity analyses excluding patients who received intravenous tPA (n = 189) and the results remained unchanged (OR 8.5, 95% CI 0.84-83.3, p = 0.071).

Conclusion: Diabetes mellitus is an independent predictors of sICH in patients with acute ischemic stroke undergoing mechanical thrombectomy, with or without IV tPA. More studies are needed to confirm our findings and to determine blood sugar control in the post-thrombectomy reduces this risk.

Abstract WMP72: High Risk Left Atrial Appendage Morphology (LAA-H) is Associated With Cardioembolic and Embolic Stroke of Unknown Source Subtypes

Background: The left atrial appendage (LAA) is the main source of thrombus in atrial fibrillation (AF); biomarkers of LAA dysfunction are associated with ischemic stroke (IS) risk in patients with AF. We hypothesized that high risk LAA features [High risk morphology (LAA-H), LAA volume (LAAV), and LAA orifice surface area (LAAOSA)] would be more prevalent among patients with cardioembolic (CE) stroke and embolic stroke of undetermined source (ESUS) than among those with non-cardioembolic stroke (NCS).

Methods: Consecutive patients with IS from a prospective comprehensive stroke center registry who previously underwent a clinically-indicated qualifying chest CT were included. Patients underwent inpatient diagnostic evaluation for ischemic stroke, and stroke subtype was determined based on ESUS criteria. LAA morphology [Low risk morphology was defined as two lobes with an acute angle between them or chicken wing morphology and LAA-H defined as all others], LAAOSA (measured in a plane parallel to the left atrium), and LAAV (measured using a volumetric analysis software) were determined using contrast enhanced thin-slice chest CT (≤2.5 mm thickness) by investigators blinded to stroke subtype.

Results: Of 1234 patients with ischemic stroke, 329 (26.7%) patients had a qualifying chest CT performed (126 CE, 116 ESUS, and 87 NCS). The baseline characteristics of patients with and without chest CT were similar. When compared to NCS, LAA-H was more prevalent in ESUS (86.4% vs. 70.1%, p=0.018) and CE stroke (82.5% vs. 70.1%, p=0.042). The LAAOSA and volume did not significantly differ between the 3 groups (Table).

Conclusion: LAA characteristics associated with cardioembolic stroke are also more prevalent in patients with ESUS. Larger studies are needed to confirm that LAA features are a risk factor for stroke among patients without AF, and whether anticoagulation is effective in patients with high-risk LAA features.

Abstract WP66: CT and Multiphase CTA Alone Can Identify Thrombectomy Candidates Beyond 6 Hours

Introduction: Current stroke guidelines recommend CT Perfusion (CTP) or MRI to identify thrombectomy candidates beyond 6 hours from stroke onset. The efficacy of more readily available NCCT and CTA in the identification of such patients is unknown. In this study, we compared the accuracy of arterial phase CTA only (sCTA) and multi-phase CTA (mCTA) with MRI in patients beyond 6 hours from onset.

Methods: We retrospectively reviewed 45 consecutive patients, presenting 6 to 24 hours from stroke onset, with known ICA or M1 occlusions. All patients had pre-treatment CTA and MRI, with diffusion weighted (DWI) and perfusion weighted imaging (PWI). MRI images were processed using RAPID. Five experienced readers independently scored ASPECTS (0-10), sCTA collateral score (0-5), and whether patients would have met DAWN or DEFUSE-3 MRI imaging criteria. After a one-month delay, grading was repeated by the same readers using NCCT and mCTA. The sensitivity and specificity for DAWN and DEFUSE-3 eligibility was examined for both sCTA and mCTA. We also examined the median DWI volume based on the combination of NCCT ASPECTS and collateral score, for both sCTA and mCTA.

Results: Sensitivity and specificity for DAWN eligibility was 91.4% and 74.8% for sCTA; 87.2% and 76.8% for mCTA. For DEFUSE-3, sensitivity and specificity was 92.3% and 46.3% for sCTA; 94.5% and 57.5% for mCTA. The higher specificity for DAWN is likely due to the more restrictive imaging criteria used in that trial. For DWI volume, the results are summarized in the graph, and show that the combination of mCTA collateral score and NCCT ASPECTS is significantly more correlated with DWI volume than sCTA (p=.0018).

Conclusions: In conclusion, the combination of NCCT ASPECTS and mCTA collateral score has high sensitivity and moderate specificity for identifying patients who meet DAWN or DEFUSE-3 criteria. NCCT ASPECTS and Multi-phase CTA collateral score are significantly more correlated with DWI volume than single-phase.

Abstract WP86: What Threshold Defines Penumbral Brain Tissue in Patients With Symptomatic Anterior Circulation Intracranial Stenosis: An Exploratory Analysis

Background: Impaired distal perfusion predicts neurological deterioration in patients with large artery atherosclerosis. We aim to determine the optimal threshold of T max delay on perfusion imaging associated with neurological deterioration in patients with symptomatic proximal anterior circulation large artery stenosis.

Methods: Data were abstracted from a prospective ischemic stroke database of consecutively enrolled patients with symptomatic proximal intracranial stenosis (internal carotid artery or M1 segment of the middle cerebral artery) who underwent magnetic resonance perfusion imaging within 24 hours of symptom onset during a 15 month period. Tissue volumes of perfusion delay T max 0-4 seconds, T max > 4 seconds, T max > 6 seconds, and T max > 8 seconds were calculated using an automated approach. A target mismatch (penumbra - core) was defined as ≥ 15 mL of brain tissue using each of the T max threshold categories. The outcome was neurological deterioration at 30 days defined as new or worsening neurological deficits that are not attributed to a non-vascular etiology.

Results: Among 52 patients with symptomatic intracranial stenosis, 26 patients met inclusion criteria. Neurological deterioration was associated with target mismatch profile defined according to T max >6 [66.7% (6/9) vs. 5.9% (1/17), p <0.01) and T max >8 [57.1% (4/7) vs. 15.8% (3/19), p = 0.05] but not T max >4 [27.3% (6/17) vs. 11.1% (1/9), p = 0.35].

Conclusion: A target mismatch profile using T max > 6 sec may optimally define tissue at risk in patients with symptomatic proximal intracranial stenosis. Larger prospective multicenter studies are needed to confirm our findings.

Abstract TP106: Cerebral Microhemorrhages and the Risk of Symptomatic Intracerebral Hemorrhage After Intravenous Thrombolysis

Introduction and Background: Cerebral microhemorrhages/microbleeds (CMBs) are proposed to increase the risk of thrombolysis-related hemorrhage. This may be because A) they are a marker of cerebral small vessel disease (a known risk factor for hemorrhagic transformation) and B) they are a feature of cerebral amyloid angiopathy (CAA). We sought to understand the relationship between CMB burden and risk of symptomatic intracerebral hemorrhage after intravenous thrombolysis in our institution.

Methods: We undertook a retrospective observational study of patients who had received intravenous thrombolysis for presumed acute ischemic stroke. Patient information was gathered including demographics, past medical history, treatment and ischemic stroke subtype. T2*/GRE imaging was inspected and the presence or absence, number and distribution of definite CMBs (according to Microbleed Anatomic Rating Scale (MARS) criteria) was documented for each patient.

Results: Four hundred and twenty five patients were identified who had received IV tPA during our study period of whom 90 (21.2%) had evidence of CMBs on T2*/GRE imaging. Three patients (3.3%) with CMBs had symptomatic intracranial hemorrhage compared with 7 (2%) of those without CMBs (p=0.49). The mean number of CMBs in those with tPA-related hemorrhage was 0.30 while in those without sICH was 0.84. 12 patients had greater than 5 microhemorrhages and in that group 0 patients had tPA-related hemorrhage. Three of the 12 cases with >5 microhemorrhages met modified Boston criteria for probable CAA.

Discussion: In contrast to other reports, we found no association between either presence or number of CMBs and sICH. The subgroup of patients with >5CMBs also did not demonstrate an increased risk. Our study was limited by the low numbers of sICH observed. The presence of CMBs may correlate with other variables that decreased the likelihood of tPA being administered such as presence of prior intracerebral hemorrhage or CAA.

Abstract TP418: Asymptomatic Hemorrhagic Infarction on 24-Hour CT Post Intravenous Recombinant Tissue Plasminogen Activator for Acute Ischemic Stroke Predicts Symptomatic Intracerebral Hemorrhage After Initiation of Antiplatelet Therapy

Background and Purpose: Predictors of symptomatic intracerebral hemorrhage (sICH) after intravenous alteplase in acute ischemic stroke (AIS) are well established however there is limited data on predictors of delayed sICH (d-sICH) (occurring > 36 hours from alteplase) after initiation of antithrombotic therapy in these patients. We hypothesize that asymptomatic hemorrhagic infarction (HI) on 24-hour brain imaging predicts delayed sICH after initiation of antiplatelet therapy.

Methods: We included consecutive patients who received intravenous alteplase for AIS over a 12-month period. All patients received brain imaging, either CT or MRI, approximately 24-hours post alteplase. Patients who were deceased or made comfort measures only or with lack of at least 48 hour follow-up, or those with parenchymal hematoma (PH) or sICH prior to antithrombotic therapy initiation were excluded. The primary outcome was delayed sICH defined using the modified SITS-MOST criteria. We compared demographic data, clinical risk factors, NIHSS score, pre-admission antithrombotic usage, and 24-hour imaging characteristics between the two groups (d-sICH vs. no d-sICH) using univariate and multivariable analyses (including variables with p<0.1 on univariable models). Analysis was done using SPSS version 20.0 and p<0.05 was considered significant.

Results: We identified 263 patients who met the inclusion criteria; 51.3% were men and the mean age was70.9 years, 8 patients (3.0%) had d-sICH and 60 patients (22.8%) had asymptomatic HI on 24-hour brain imaging (CT or MRI). On univariate analyses, predictors of d-sICH were diabetes [50.0% (4/8) vs. 23.1% (59/255), p = 0.097} and asymptomatic HI on CT [50.0% (4/8) vs. 13.1 (31/236), p=0.016] and a trend for asymptomatic hemorrhage on MRI [60.0% (3/5) vs. 25.0% (42/168), p = 0.11]. In a multivariable model, both diabetes (OR 5.1 95% CI 1.1 - 23.3, p=0.037) and asymptomatic hemorrhage on CT (OR 8.9 95% CI 1.9 - 41.7 p = 0.005) predicted d-sICH.

Conclusion: In AIS patient receiving alteplase, asymptomatic HI on 24-hour brain imaging predicts d-sICH after antithrombotic treatment. Future studies are needed to confirm our findings and investigate best timing of initiating antiplatelet therapy and other measures to reduce d-sICH risk.

Abstract TP220: Volume of White Matter Disease Prior to Ischemic Stroke may Predict Outcome

Background: White matter disease (WMD) and microhemorrhages (MH) present at the time of stroke have been linked to outcome, yet few have investigated changes in the time leading up to stroke. Magnetic Resonance Imaging (MRI) characteristics before a stroke may shed light on the severity of outcomes following stroke.

Methods: We retrospectively identified patients admitted to our institution for ischemic stroke between 5/16-12/17 who had an MRI in the 1-24 months prior to their stroke. After collecting clinical and demographic data, automatic segmentations of gray and white matter volumes and manual segmentation of WMD and MH (size<10mm) were completed using 3D Slicer 4.5 and 4.9, respectively. Groups were created based on modified Rankin Scale score (mRS) at 90 days; an mRS of 3-6 was considered a poor outcome. Univariate analyses and multivariate regression models were performed to determine factors associated with poor outcome.

Results: Among the 48 patients in our study (mean age 68, 50% female), 29 patients (60%) had poor outcome. Poor outcome was associated with pre-existing WMD volume (21.9+/-23.6 vs 6.1+/-5.7mL, p= 0.002), and WMD volume at time of stroke (26.4+/-24.9 vs 8.8+/-6.0mL, p=0.001). There was a trend towards poor outcome in older patients (p=0.073), women (p=0.075), higher NIHSS score (p=0.066), and need for thrombectomy (p=0.065). History of prior stroke was not associated with poor outcome (p=0.74), larger pre-existing WMD volumes (14.3+/-19.3 vs 19.5+/-22.6mL, p=0.47) or larger WMD volumes at time of stroke (18.7±22.5 vs 21.5±18.8mL, p=0.67). After adjusting for confounders, pre-existing WMD volume showed a trend to predict poor outcome (adjusted OR 1.086 per one point increase, 95% CI 0.987-1.195, p=0.09), as did WMD volume at the time of stroke (adjusted OR 1.103 per one point increase, 95% CI 0.992-1.226, p=0.07).

Conclusions: Greater volume of WMD at time of and prior to admission for stroke may be independent predictors of poor outcome. These results should be validated in subsequent studies.

Abstract TP248: Distribution and Number of Cerebral Microhemorrhages Differ According to Ischemic Stroke Subtype

Introduction: Cerebral microhemorrhages/microbleeds (CMBs) are foci of hemosiderin deposition that appear as well-circumscribed hypointensities on T2*-weighted gradient echo magnetic resonance imaging(1). They are a bio marker of small vessel disease but may also be seen as a consequence of thromboembolism to the brain and are commonly seen in the wake of acute ischemic stroke(2). We sought to understand the relationship between CMB burden and distribution and ischemic stroke subtype.

Methods: We undertook a retrospective observational study of patients admitted for management of acute ischemic stroke via clinical data archived as part of an institutional quality improvement project. Patient information was gathered including demographics, past medical history, treatment and ischemic stroke subtype. T2*/GRE imaging was inspected and the presence or absence, number and distribution of definite CMBs (according to Microbleed Anatomic Rating Scale (MARS) criteria(3) was documented for each patient.

Results: 695 patients with acute ischemic stroke confirmed on imaging had T2*/GRE imaging of adequate quality. The mean age in our population was 71.14 (+-15.28). 22.3% of the population had CMBs and the average number of CMBs per person was 0.66. The mean number of CMBs was higher in patients with stroke of small vessel etiology (mean of 1.97) compared with the group as a whole and this difference persisted after adjusting for age and hypertension (p=0.024). Patients with stroke of cardioembolic etiology had a higher proportion of lobar microhemorrhages (11.83%) compared with those with stroke of small vessel etiology (6.90%) though this difference did not persist after adjusting for age.

Discussion: Distribution and number of CMBs differ based on stroke pathophysiology. CMB pattern may aid in distinguishing strokes of small vessel etiology from other ischemic stroke subtypes.

Abstract WMP61: Recurrent Stroke Rates in Short versus Long Term Cardiac Monitoring in Patients With Embolic Stroke of Unknown Source

Background: Outpatient cardiac monitoring for 30 days or longer increases detection rates of paroxysmal atrial fibrillation (AF) after cryptogenic stroke, but the ideal duration of monitoring remains unclear. Two commonly used methods of prolonged outpatient cardiac monitoring are 30-day continuous telemetry and insertable cardiac monitors (ICM). We aim to compare rates of AF detection and recurrent stroke between patients with Embolic Stroke of Unknown Source (ESUS) monitored for approximately 30 days (short term) vs. beyond 30 days with ICM (long term).

Methods: We analyzed a single center retrospective cohort of patients discharged with a diagnosis of ESUS over a two-year period. Patients were divided into two groups based on implemented cardiac monitoring method: short-term (30-day non-invasive monitor) and long-term (ICM

Results: We identified 117 ESUS patients; 71 patients underwent short-term monitoring and 46 patients underwent long-term monitoring. After a median follow-up of 259 days (IQR 166-468 days), AF was detected in 11.2% (8/71) of patients undergoing short-term cardiac monitoring and 19.6% (9/46) of patients on long-term monitoring; 77.8% of AF was detected beyond 30 days. Recurrent stroke occurred in 12.8% (15/117) of patients. Rates of recurrent stroke were lower in patients undergoing long-term cardiac monitoring vs. only short-term monitoring [adjusted hazard ratio 0.12, 95% confidence interval 0.02-0.89, p = 0.038].

Conclusion: In a real world ESUS patient cohort, long term monitoring was associated with increased detection of AF and reduced risk of recurrent stroke. Large multicenter prospective studies are needed to confirm our findings.