Trial of Endovascular Treatment of Acute Basilar-Artery Occlusion

BACKGROUND

Data from trials investigating the effects and risks of endovascular thrombectomy for the treatment of stroke due to basilar-artery occlusion are limited.

METHODS

We conducted a multicenter, prospective, randomized, controlled trial of endovascular thrombectomy for basilar-artery occlusion at 36 centers in China. Patients were assigned, in a 2:1 ratio, within 12 hours after the estimated time of basilar-artery occlusion to receive endovascular thrombectomy or best medical care (control). The primary outcome was good functional status, defined as a score of 0 to 3 on the modified Rankin scale (range, 0 [no symptoms] to 6 [death]), at 90 days. Secondary outcomes included a modified Rankin scale score of 0 to 2, distribution across the modified Rankin scale score categories, and quality of life. Safety outcomes included symptomatic intracranial hemorrhage at 24 to 72 hours, 90-day mortality, and procedural complications.

RESULTS

Of the 507 patients who underwent screening, 340 were in the intention-to-treat population, with 226 assigned to the thrombectomy group and 114 to the control group. Intravenous thrombolysis was used in 31% of the patients in the thrombectomy group and in 34% of those in the control group. Good functional status at 90 days occurred in 104 patients (46%) in the thrombectomy group and in 26 (23%) in the control group (adjusted rate ratio, 2.06; 95% confidence interval [CI], 1.46 to 2.91, P<0.001). Symptomatic intracranial hemorrhage occurred in 12 patients (5%) in the thrombectomy group and in none in the control group. Results for the secondary clinical and imaging outcomes were generally in the same direction as those for the primary outcome. Mortality at 90 days was 37% in the thrombectomy group and 55% in the control group (adjusted risk ratio, 0.66; 95% CI, 0.52 to 0.82). Procedural complications occurred in 14% of the patients in the thrombectomy group, including one death due to arterial perforation.

CONCLUSIONS

In a trial involving Chinese patients with basilar-artery occlusion, approximately one third of whom received intravenous thrombolysis, endovascular thrombectomy within 12 hours after stroke onset led to better functional outcomes at 90 days than best medical care but was associated with procedural complications and intracerebral hemorrhage. (Funded by the Program for Innovative Research Team of the First Affiliated Hospital of USTC and others; ATTENTION ClinicalTrials.gov number, NCT04751708.).

Endovascular treatment for acute Basilar Artery Occlusion - a multicenter randomized controlled trial (ATTENTION)

BACKGROUND AND HYPOTHESIS

Recently, two multicenter randomized controlled trials (RCT) failed to show a significantly beneficial effect of endovascular treatment (EVT) in patients with acute basilar artery occlusion (BAO). However, both trials suffered from equipoise issues which may have hindered the validity of the trial results. Therefore, additional RCT studies are needed to explore the potential benefit of EVT in patients presenting with BAO.

STUDY DESIGN

ATTENTION is an investigator-initiated, multicenter, prospective, randomized, controlled clinical trial with open-label treatment and blinded outcome assessment (PROBE) of EVT versus best medical management (BMM). The primary effect parameter is a modified Rankin Score of 0-3 at day 90.

DISCUSSION

ATTENTION will provide evidence for the efficacy and safety of EVT in stroke patients within 12 hours after BAO.

Clinical effectiveness of endovascular stroke treatment in the early and extended time windows

BACKGROUND

The clinical efficacy of mechanical thrombectomy has been unequivocally demonstrated in multiple randomized clinical trials. However, these studies were performed in carefully selected centers and utilized strict inclusion criteria.

AIM

We aimed to assess the clinical effectiveness of mechanical thrombectomy in a prospective registry.

METHODS

A total of 2008 patients from 76 sites across 12 countries were enrolled in a prospective open-label mechanical thrombectomy registry. Patients were categorized into the corresponding cohorts of the SWIFT-Prime, DAWN, and DEFUSE 3 trials according to the basic demographic and clinical criteria without considering specific parenchymal imaging findings. Baseline and outcome variables were compared across the corresponding groups.

RESULTS

As compared to the treated patients in the actual trials, registry-derived patients tended to be younger and had lower baseline ASPECTS. In addition, time to treatment was earlier and the use of intravenous tissue plasminogen activator (IV-tPA) and general anesthesia were higher in DAWN- and DEFUSE-3 registry derived patients versus their corresponding trials. Reperfusion rates were higher in the registry patients. The rates of 90-day good outcome (mRS0-2) in registry-derived patients were comparable to those of the patients treated in the corresponding randomized clinical trials (SWIFT-Prime, 64.5% vs. 60.2%; DAWN, 50.4% vs. 48.6%; Beyond-DAWN: 52.4% vs. 48.6%; DEFUSE 3, 52% vs. 44.6%, respectively; all P > 0.05). Registry-derived patients had significant less disability than the corresponding randomized clinical trial controls (ordinal modified Rankin Scale (mRS) shift odds ratio (OR), P < 0.05 for all).

CONCLUSION

Our study provides favorable generalizability data for the safety and efficacy of thrombectomy in the "real-world" setting and supports that patients may be safely treated outside the constraints of randomized clinical trials.

Influence of time to endovascular stroke treatment on outcomes in the early versus extended window paradigms

BACKGROUND

The effect of time from stroke onset to thrombectomy in the extended time window remains poorly characterized.

AIM

We aimed to analyze the relationship between time to treatment and clinical outcomes in the early versus extended time windows.

METHODS

Proximal anterior circulation occlusion patients from a multicentric prospective registry were categorized into early (≤6 h) or extended (>6-24 h) treatment window. Patients with baseline National Institutes of Health Stroke Scale (NIHSS) ≥ 10 and intracranial internal carotid artery or middle cerebral artery-M1-segment occlusion and pre-morbid modified Rankin scale (mRS) 0-1 ("DAWN-like" cohort) served as the population for the primary analysis. The relationship between time to treatment and 90-day mRS, analyzed in ordinal (mRS shift) and dichotomized (good outcome, mRS 0-2) fashion, was compared within and across the extended and early windows.

RESULTS

A total of 1603 out of 2008 patients qualified. Despite longer time to treatment (9[7-13.9] vs. 3.4[2.5-4.3] h, p < 0.001), extended-window patients (n = 257) had similar rates of symptomatic intracranial hemorrhage (sICH; 0.8% vs. 1.7%, p = 0.293) and 90-day-mortality (10.5% vs. 9.6%, p = 0.714) with only slightly lower rates of 90-day good outcomes (50.4% vs. 57.6%, p = 0.047) versus early-window patients (n = 709). Time to treatment was associated with 90-day disability in both ordinal (adjusted odd ratio (aOR), ≥ 1-point mRS shift: 0.75; 95%CI [0.66-0.86], p < 0.001) and dichotomized (aOR, mRS 0-2: 0.73; 95%CI [0.62-0.86], p < 0.001) analyses in the early- but not in the extended-window (aOR, mRS shift: 0.96; 95%CI [0.90-1.02], p = 0.15; aOR, mRS0-2: 0.97; 95%CI [0.90-1.04], p = 0.41). Early-window patients had significantly lower 90-day functional disability (aOR, mRS shift: 1.533; 95%CI [1.138-2.065], p = 0.005) and a trend towards higher rates of good outcomes (aOR, mRS 0-2: 1.391; 95%CI [0.972-1.990], p = 0.071).

CONCLUSIONS

The impact of time to thrombectomy on outcomes appears to be time dependent with a steep influence in the early followed by a less significant plateau in the extended window. However, every effort should be made to shorten treatment times regardless of ischemia duration.

Which Acute Ischemic Stroke Patients Are Fast Progressors?: Results From the ESCAPE Trial Control Arm

BACKGROUND AND PURPOSE

Fast infarct progression in acute ischemic stroke has a severe impact on patient prognosis and benefit of endovascular thrombectomy. In this post hoc analysis of the ESCAPE trial (Endovascular Treatment for Small Core and Proximal Occlusion Ischemic Stroke), we identified acute ischemic stroke patients with rapid infarct growth and investigated their baseline clinical and imaging characteristics.

METHODS

Control arm patients were included if they had follow-up imaging at 2-8 hours without substantial recanalization, and if their baseline Alberta Stroke Program Early CT Score was ≥9. Fast infarct progression was defined as Alberta Stroke Program Early CT Score decay ≥3 points from baseline to 2- to 8-hour follow-up imaging. Clinical and imaging baseline characteristics were compared between fast progressors and other patients, and occlusion site and collateral flow patterns were assessed in detail.

RESULTS

Fast infarct progression occurred in 15 of 43 included patients (34.9%). Fast progressors had worse collaterals (poor in 3/15 [20%] versus 0/28 patients, P=0.021) and more carotid-T or -L occlusions (8/15 [53.4%] versus 3/28[10.7%], P=0.021). In 8 out of 15 (53.3%), occlusion site and circle of Willis configuration prevented collateral flow via the anterior or posterior cerebral artery.

CONCLUSIONS

Most patients with fast infarct progression had terminal carotid occlusions and impaired collateral flow via the anterior or posterior cerebral artery, indicating that occlusion location and intracranial vascular anatomy are relevant for infarct progression.

First pass effect in patients with large vessel occlusion strokes undergoing neurothrombectomy: insights from the Trevo Retriever Registry

BACKGROUND

First pass effect (FPE), defined as near-total/total reperfusion of the territory (modified Thrombolysis in Cerebral Infarction (mTICI) 2c/3) of the occluded artery after a single thrombectomy attempt (single pass), has been associated with superior safety and efficacy outcomes than in patients not experiencing FPE.

OBJECTIVE

To characterize the clinical features, incidence, and predictors of FPE in the anterior and posterior circulation among patients enrolled in the Trevo Registry.

METHODS

Data were analyzed from the Trevo Retriever Registry. Univariate and multivariable analyses were used to assess the relationship of patient (demographics, clinical, occlusion location, collateral grade, Alberta Stroke Program Early CT Score (ASPECTS)) and device/technique characteristics with FPE (mTICI 2c/3 after single pass).

RESULTS

FPE was achieved in 27.8% (378/1358) of patients undergoing anterior large vessel occlusion (LVO) thrombectomy. Multivariable regression analysis identified American Society of Interventional and Therapeutic Neuroradiology (ASITN) levels 2-4, higher ASPECTS, and presence of atrial fibrillation as independent predictors of FPE in anterior LVO thrombectomy. Rates of modified Rankin Scale (mRS) score 0-2 at 90 days were higher (63.9% vs 53.5%, p<0.0006), and 90-day mortality (11.4% vs 12.8%, p=0.49) was comparable in the FPE group and non-FPE group. Rate of FPE was 23.8% (19/80) among basilar artery occlusion strokes, and outcomes were similar between FPE and non-FPE groups (mRS score 0-2, 47.4% vs 52.5%, p=0.70; mortality 26.3% vs 18.0%, p=0.43). Notably, there were no difference in outcomes in FPE versus non-FPE mTICI 2c/3 patients.

CONCLUSION

Twenty-eight percent of patients undergoing anterior LVO thrombectomy and 24% of patients undergoing basilar artery occlusion thrombectomy experience FPE. Independent predictors of FPE in anterior circulation LVO thrombectomy include higher ASITN levels, higher ASPECTS, and the presence of atrial fibrillation.

Stroke Imaging Selection Modality and Endovascular Therapy Outcomes in the Early and Extended Time Windows

BACKGROUND AND PURPOSE

Advanced imaging has been increasingly used for patient selection in endovascular stroke therapy. The impact of imaging selection modality on endovascular stroke therapy clinical outcomes in extended time window remains to be defined. We aimed to study this relationship and compare it to that noted in early-treated patients.

METHODS

Patients from a prospective multicentric registry (n=2008) with occlusions involving the intracranial internal carotid or the M1- or M2-segments of the middle cerebral arteries, premorbid modified Rankin Scale score 0 to 2 and time to treatment 0 to 24 hours were categorized according to treatment times within the early (0-6 hour) or extended (6-24 hour) window as well as imaging modality with noncontrast computed tomography (NCCT)±CT angiography (CTA) or NCCT±CTA and CT perfusion (CTP). The association between imaging modality and 90-day modified Rankin Scale, analyzed in ordinal (modified Rankin Scale shift) and dichotomized (functional independence, modified Rankin Scale score 0-2) manner, was evaluated and compared within and across the extended and early windows.

RESULTS

In the early window, 332 patients were selected with NCCT±CTA alone while 373 also underwent CTP. After adjusting for identifiable confounders, there were no significant differences in terms of 90-day functional disability (ordinal shift: adjusted odd ratio [aOR], 0.936 [95% CI, 0.709-1.238], P=0.644) or independence (aOR, 1.178 [95% CI, 0.833-1.666], P=0.355) across the CTP and NCCT±CTA groups. In the extended window, 67 patients were selected with NCCT±CTA alone while 180 also underwent CTP. No significant differences in 90-day functional disability (aOR, 0.983 [95% CI, 0.81-1.662], P=0.949) or independence (aOR, 0.640 [95% CI, 0.318-1.289], P=0.212) were seen across the CTP and NCCT±CTA groups. There was no interaction between the treatment time window (0-6 versus 6-24 hours) and CT selection modality (CTP versus NCCT±CTA) in terms of functional disability at 90 days (P=0.45).

CONCLUSIONS

CTP acquisition was not associated with better outcomes in patients treated in the early or extended time windows. While confirmatory data is needed, our data suggests that extended window endovascular stroke therapy may remain beneficial even in the absence of advanced imaging.

0113 Evaluating Closed-Loop Auditory Stimulation During Sleep as an Intervention to Improve Memory Consolidation Deficits in Schizophrenia

Introduction

Converging evidence supports the hypothesis that reduced sleep spindles and spindle-slow oscillation (SO) coordination contribute to cognitive deficits in schizophrenia. Closed-loop auditory stimulation in healthy adults increases sleep spindles and improves declarative memory consolidation. Here we investigated whether closed-loop auditory stimulation also improves sleep-dependent procedural memory consolidation as a first step towards an intervention in schizophrenia.

Methods

Thirteen healthy adults participated in two nap sessions (stimulation or detection only) with polysomnography in a counterbalanced order. Participants were trained on the finger tapping Motor Sequence Task (MST), which measures sleep-dependent motor procedural memory consolidation, prior to napping and were tested after awakening. We detected the negative peak of SOs during non-REM sleep and, in the stimulation condition, delivered 50ms of pink noise during the SO up-state.

Results

Auditory stimulation increased SOs and spindles during the SO up-state in a frontocentral cluster of electrodes 800-1200ms after stimulation compared to detection only (p&lt;0.05). Stimulation also showed promise for improving memory consolidation (33% increase in MST overnap improvement from detection-only) but this did not reach significance in this small sample and data collection is ongoing.

Conclusion

Auditory stimulation evoked coordinated spindle-SO events that mediate memory consolidation, but more subjects are needed to evaluate whether it also improves memory. If it does, we will test the effects of stimulation on sleep-dependent memory deficits in patients with schizophrenia. Closed-loop auditory stimulation shows promise as a safe, scalable intervention for cognitive deficits that can be implemented at home with commercially available devices.

Support

R01 MH67720 (DSM & RS), NIH-NHLBI 5T32HL007901-17 (BB), K24MH099421 (DSM), and Simons Foundation (DSM).

Discrepancies between current and ideal endovascular stroke treatment practice in Europe and North America: Results from UNMASK EVT, a multidisciplinary survey

BACKGROUND

Since 2015, endovascular therapy has been established as a standard of care for acute stroke. This has caused major challenges regarding the organization of systems of care, which have to meet the increasing demand for thrombectomies. This study aims to evaluate how endovascular therapy decisions made by European and North American physicians under their current local resources differ from those made under assumed ideal conditions.

METHODS

In an international, multidisciplinary survey, physicians involved in acute stroke care were asked to give their treatment decisions to 10 out of 22 randomly assigned stroke case-scenarios. Participants stated (a) their treatment approach under assumed ideal conditions (without any external limitations) and (b) the treatment they would pursue under their current local resources. Resources gaps (ideal minus current endovascular therapy rates) were calculated for different countries/states/provinces and correlated to economic and healthcare key metrics (gross domestic product-per-capita, public or private health insurance coverage, etc.).

RESULTS

A total of 607 physicians, among them 218 from North America and 136 from 25 European countries, responded to the survey. Resources gaps in the majority of North American states/provinces and European countries were small (<5%). The highest gaps were observed among few European countries, namely Poland (30%) and the United Kingdom (33%). The magnitude of the resources gap did not correlate to national economic or healthcare metrics.

DISCUSSION AND CONCLUSION

In the majority of North American states/provinces and European countries covered in this study, the discrepancy between endovascular therapy decisions under current local resources and assumed ideal conditions seems to be small, even in countries with a limited economic status and healthcare infrastructure.

Should posterior cerebral artery occlusions be recanalized? Insights from the Trevo Registry

BACKGROUND AND PURPOSE

The purpose of this study was to evaluate the safety and effectiveness of mechanical thrombectomy (MT) in patients with acute ischaemic stroke related to isolated and primary posterior cerebral artery (PCA) occlusions amongst the patients enrolled in the multicentre post-market Trevo Registry.

METHOD

Amongst the 2008 patients enrolled in the Trevo Registry with acute ischaemic stroke due to large vessel occlusion treated by MT, 22 patients (1.1%) [10 females (45.5%), mean age 66.2 ± 14.3 years (range 28-91)] had a PCA occlusion [17 P1 (77.3%) and five P2 occlusions (22.7%)]. Recanalization after the first Trevo (Stryker, Fremont, CA, USA) pass and at the end of the procedure was rated using the modified Thrombolysis in Cerebral Infarction (mTICI) score. Procedure-related complications (i.e. groin puncture complication, perforation, symptomatic haemorrhage, embolus in a new territory) were also recorded. The modified Rankin Scale at 90 days was assessed.

RESULTS

Median National Institutes of Health Stroke Scale at admission was 14 (interquartile range 8-16). Stroke aetiology was cardio-embolic in 68.2% of cases. Half of the patients (11/22) received intravenous tissue plasminogen activator. 54.5% of the patients were treated under general anaesthesia. Reperfusion (i.e. mTICI 2b or 3) after first pass was obtained in 65% of cases. Final mTICI 2b-3 reperfusion was obtained in all cases. Only one (4.5%) procedure-related complication was recorded (puncture site) that resolved after surgery. At 90-day follow-up, modified Rankin Scale 0-2 was obtained in 59% of the patients and 9.1% died within the first 3 months after MT.

CONCLUSION

Mechanical thrombectomy for PCA occlusions seems to be safe (<5% procedure-related complications) and effective. Larger repository datasets are needed.

WEAVE Trial: Final Results in 152 On-Label Patients

Background and Purpose- The WEAVE trial (Wingspan Stent System Post Market Surveillance) is a postmarket surveillance trial mandated by the Food and Drug Administration to assess the periprocedural safety of the Wingspan Stent system in the treatment of symptomatic intracranial atherosclerotic disease. Methods- A total of 152 consecutive patients who met the Food and Drug Administration on-label usage criteria were enrolled at 24 hospitals and underwent angioplasty and stenting with the Wingspan stent. On-label criteria included age 22 to 80 years, symptomatic intracranial atherosclerotic stenosis of 70% to 99%, baseline modified Rankin Scale score ≤3, ≥2 strokes in the vascular territory of the stenotic lesion with at least 1 stroke while on medical therapy, and stenting of the lesion ≥8 days after the last stroke. The primary analysis assessed the periprocedural stroke, bleed, and death rate within 72 hours of the procedure with adjudication by a core study Stroke Neurologist. Results- The trial was stopped early after interim analysis of 152 consecutive patients demonstrated a lower than expected 2.6% (4/152 patients) periprocedural stroke, bleed, and death rate. This was lower than the 4% periprocedural primary event safety benchmark set for the interim analysis in the study. A total of 97.4% (148/152) patients were event-free at 72 hours, 1.3% (2/152) had nonfatal strokes, and 1.3% (2/152) of patients died. Conclusions- With experienced interventionalists, and proper patient selection following the on-label usage guidelines, the use of the Wingspan stent for intracranial atherosclerotic disease demonstrated a low periprocedural complication rate and excellent safety profile. This is the largest on-label, multicenter, prospective trial of the Wingspan stent system to date with the lowest reported complication rate. Clinical Trial Registration- URL: https://www.clinicaltrials.gov . Unique identifier: NCT02034058.

Comparative Safety and Efficacy of Modified TICI 2b and TICI 3 Reperfusion in Acute Ischemic Strokes Treated With Mechanical Thrombectomy

BACKGROUND

Mechanical thrombectomy (MT) is the current standard of care for acute ischemic stroke (AIS) patients with emergent large-vessel occlusions (ELVO). Successful reperfusion of ELVO is traditionally defined by modified Thrombolysis in Cerebral Infarction (mTICI) grades of 2b or 3.

OBJECTIVE

To evaluate the comparative safety and efficacy of mTICI 2b and mTICI 3 reperfusion in AIS patients treated with MT.

METHODS

Consecutive ELVO patients who underwent MT at 6 high-volume centers were included in this analysis. Standard safety (3-mo mortality, symptomatic intracranial hemorrhage [sICH]) and efficacy (absolute and relative reduction in NIHSS-scores during hospitalization, functional-improvement [shift analysis in mRS-scores], and functional-independence [mRS-scores of 0-2] at 3-mo) were compared between patients who had mTICI 2b and mTICI 3 reperfusion post MT.

RESULTS

A total of 416 ELVO patients achieved successful reperfusion with mTICI 2b (n = 216) and mTICI 3 (n = 200) following MT. The mTICI 3 group had significantly (P < .05) greater absolute (11 vs 9 points) and relative (77% vs 63%) reduction in NIHSS-scores during hospitalization, lower sICH (6% vs 12%), and higher 3-mo functional-independence (55% vs 44%) rates. Successful reperfusion with mTICI 3 was independently (P < .05) associated with greater absolute and relative reduction in NIHSS-scores during hospitalization as well as higher odds of 3-mo functional improvement (common odds ratios: 1.67; 95% confidence interval: 1.10-2.56) and functional independence (odds ratio: 2.08; 95% confidence interval: 1.22-3.53) in multivariable regression models adjusting for confounders.

CONCLUSION

Successful reperfusion with mTICI 3 was associated with greater neurological improvement during hospitalization and better 3-mo functional outcomes in comparison to mTICI 2b reperfusion.

Trevo 2000: Results of a Large Real-World Registry for Stent Retriever for Acute Ischemic Stroke

Background Recent randomized controlled trials show benefit of thrombectomy for large vessel occlusion in stroke. Real-world data aid in assessing reproducibility of outcomes outside of clinical trials. The Trevo Retriever Registry is a multicenter, international, prospective study designed to assess outcomes in a large cohort of patients. Methods and Results The Trevo Registry is a prospective database of patients with large vessel occlusion treated with the Trevo device as the first device. The primary end point is revascularization based on modified Thrombolysis in Cerebral Infarction score and secondary end points include 90-day modified Rankin Scale, 90-day mortality, neurological deterioration at 24 hours, and device/procedure related adverse events. Year 2008 patients were enrolled at 76 centers in 12 countries. Median admission National Institutes of Health Stroke Scale was 16 (interquartile range, 11-20). Occlusion sites were internal carotid artery (17.8%), middle cerebral artery (73.5%), posterior circulation (7.1%), and distal vascular locations (1.6%). A modified Thrombolysis in Cerebral Infarction 2b or 3 was achieved in 92.8% (95% CI, 91.6, 93.9) of procedures, with 55.3% (95% CI, 53.1, 57.5) of patients achieving modified Rankin Scale ≤2 at 3 months. Patients meeting revised 2015 American Heart Association criteria for thrombectomy had a 59.7% (95% CI , 56.0; 63.4) modified Rankin Scale 0 to 2 at 3 months, whereas 51.4% treated outside of American Heart Association criteria had modified Rankin Scale 0 to 2. 51.4% (95% CI , 49.6, 55.4). Symptomatic intracranial hemorrhage rate was 1.7% (95% CI , 1.2, 2.4). Conclusions The Trevo Retriever Registry represents real-world data with stent retriever. The registry demonstrates similar reperfusion rates and outcomes in the community compared with rigorous centrally adjudicated clinical trials. Future subgroup analysis of this cohort will assist in identifying areas of future research. Clinical Trial Registration URL : https://www.clinicaltrials.gov . Unique identifier: NCT 02040259.

Influence of Guidelines in Endovascular Therapy Decision Making in Acute Ischemic Stroke: Insights From UNMASK EVT

Background and Purpose- The American Heart Association and the American Stroke Association guidelines for early management of patients with ischemic stroke offer guidance to physicians involved in acute stroke care and clarify endovascular treatment indications. The purpose of this study was to assess concordance of physicians' endovascular treatment decision-making with current American Heart Association and the American Stroke Association stroke treatment guidelines using a survey-approach and to explore how decision-making in the absence of guideline recommendations is approached. Methods- In an international cross-sectional survey (UNMASK-EVT), physicians were randomly assigned 10 of 22 case scenarios (8 constructed with level 1A and 11 with level 2B evidence for endovascular treatment and 3 scenarios without guideline coverage) and asked to declare their treatment approach (1) under their current local resources and (2) assuming there were no external constraints. The proportion of physicians offering endovascular therapy (EVT) was calculated. Subgroup analysis was performed for different specialties, geographic regions, with regard to physicians' age, endovascular, and general stroke treatment experience. Results- When facing level 1A evidence, participants decided in favor of EVT in 86.8% under current local resources and in 90.6% under assumed ideal conditions, that is, 9.4% decided against EVT even under assumed ideal conditions. In case scenarios with level 2B evidence, 66.3% decided to proceed with EVT under current local resources and 69.7% under assumed ideal conditions. Conclusions- There is potential for improving thinking around the decision to offer endovascular treatment, since physicians did not offer EVT even under assumed ideal conditions in 9.4% despite facing level 1A evidence. A majority of physicians would offer EVT even for level 2B evidence cases.

Factors Associated With the Decision-Making on Endovascular Thrombectomy for the Management of Acute Ischemic Stroke

Background and Purpose—

Little is known about the real-life factors that clinicians use in selection of patients that would receive endovascular treatment (EVT) in the real world. We sought to determine patient, practitioner, and health system factors associated with therapeutic decisions around endovascular treatment.

Methods—

We conducted a multinational cross-sectional web-based study comprising of 607 clinicians and interventionalists from 38 countries who are directly involved in acute stroke care. Participants were randomly allocated to 10 from a pool of 22 acute stroke case scenarios. Each case was classified as either Class I, Class II, or unknown evidence according to the current guidelines. We used logistic regression analysis applying weight of evidence approach. Main outcome measures were multilevel factors associated with EVT, adherence to current EVT guidelines, and practice gaps between current and ideal practice settings.

Results—

Of the 1330 invited participants, 607 (45.6%) participants completed the study (53.7% neurologists, 28.5% neurointerventional radiologists, 17.8% other clinicians). The weighed evidence approach revealed that National Institutes of Health Stroke Scale (34.9%), level of evidence (30.2%), ASPECTS (Alberta Stroke Program Early CT Score) or ischemic core volume (22.4%), patient’s age (21.6%), and clinicians’ experience in EVT use (19.3%) are the most important factors for EVT decision. Of 2208 responses that met Class I evidence for EVT, 1917 (86.8%) were in favor of EVT. In case scenarios with no available guidelines, 1070 of 1380 (77.5%) responses favored EVT. Comparison between current and ideal practice settings revealed a small practice gap (941 of 6070 responses, 15.5%).

Conclusions—

In this large multinational survey, stroke severity, guideline-based level of evidence, baseline brain imaging, patients’ age and physicians’ experience were the most relevant factors for EVT decision-making. The high agreement between responses and Class I guideline recommendations and high EVT use even when guidelines were not available reflect the real-world acceptance of EVT as standard of care in patients with disabling acute ischemic stroke.

An international multicenter retrospective study to survey the landscape of thrombectomy in the treatment of anterior circulation acute ischemic stroke: outcomes with respect to age

Background

Thrombectomy is an efficacious treatment for acute ischemic stroke (AIS). However, relatively few studies to date have specifically examined the impact and clinical implications of age on outcomes for thrombectomy in anterior AIS.

Objective

To provide a snapshot of patient metrics and outcomes with respect to age following thrombectomy for anterior AIS to supplement the current body of data for predictors of clinical outcomes in a real-world setting.

Methods

Data were collected for 20 consecutive patients with AIS treated with thrombectomy at 15 high-volume stroke centers across North America between 2015 and 2016. Patients with anterior occlusions were dichotomized based on whether they were older or younger than 80 years. Ordinal logistic regression analyzed how clinical variables impacted disability using 90-day modified Rankin Scale (mRS) scores.

Results

Adequate revascularization (TICI ≥2B) was achieved in 92.3% of patients aged <80 years with an average 1.7±0.1 passes taken with the primary technique and in 88.0% of patients aged ≥80 years with an average 1.7±0.2 passes. Despite similar baseline characteristics, mRS scores were significantly higher in older patients postoperatively and at 90 days after intervention. Age was a significant predictor of 90-day mRS across the study population.

Conclusion

This analysis affirms age is a significant determinant of 90-day mRS scores following thrombectomy for large vessel anterior AIS. Further investigation into risks faced by elderly patients during thrombectomy may provide actionable information to help refine patient selection and improve outcomes.

'Real-world' comparison of first-line direct aspiration and stent retriever mechanical thrombectomy for the treatment of acute ischemic stroke in the anterior circulation: a multicenter international retrospective study

BACKGROUND

Thrombectomy for anterior large vessel occlusion less than 24 hours since last known well is now standard of care. Certain aspects of clinical trials may limit generalizability to 'real-world' practice.

OBJECTIVE

To compare revascularization rates and outcomes for direct aspiration (ADAPT) and stent retriever thrombectomy following anterior acute ischemic stroke (AIS) in a real-life setting.

METHODS

Data from the most recent 20 consecutive patients with AIS treated with mechanical thrombectomy between 2015 and 2016 were collected from 15 high-volume stroke centers across North America for a total of 300 cases. Patients with proximal anterior large vessel occlusions were dichotomized by primary treatment technique. Ordinal logistic regression assessed the effects of clinical variables on patient disability using 90-day modified Rankin Scale (mRS) scores.

RESULTS

Adequate revascularization (Thrombolysis in Cerebral Infarction ≥2b) was ultimately achieved in 91.2% of first-line direct aspiration (ADAPT) cases with an average of 1.9±1.9 passes and in 87.5% of stent retriever cases with an average of 1.7±1.0 passes. Time from groin puncture to revascularization was shorter for ADAPT cases. The mean 90-day mRS score for both groups was 3.0±2.4. Number of passes using primary technique, and postintervention intracranial hemorrhage, were significant predictors of 90-day mRS scores after ADAPT, while age and preprocedure mRS score were predictive of outcomes following first-line stent retriever.

CONCLUSIONS

Our data show similar adequate revascularization rates and 90-day functional outcomes for first-line direct aspiration and stent retrievers for anterior large vessel occlusion in a real-world setting. These results support the findings of other prospective trials evaluating the two techniques.

Aspiration thrombectomy versus stent retriever thrombectomy as first-line approach for large vessel occlusion (COMPASS): a multicentre, randomised, open label, blinded outcome, non-inferiority trial

BACKGROUND

Stent retriever thrombectomy of large-vessel occlusion results in better outcomes than medical therapy alone. Alternative thrombectomy strategies, particularly a direct aspiration as first pass technique, while promising, have not been rigorously assessed for clinical efficacy in randomised trials. We designed COMPASS to assess whether patients treated with aspiration as first pass have non-inferior functional outcomes to those treated with a stent retriever as first line.

METHODS

We did a multicentre, randomised, open label, blinded outcome, core lab adjudicated non-inferiority trial at 15 sites (ten hospitals and four specialty clinics in the USA and one hospital in Canada). Eligible participants were patients presenting with acute ischaemic stroke from anterior circulation large-vessel occlusion within 6 h of onset and an Alberta Stroke Program Early CT Score of greater than 6. We randomly assigned participants (1:1) via a central web-based system without stratification to either direct aspiration first pass or stent retriever first line thrombectomy. Those assessing primary outcomes via clinical examinations were masked to group assignment as they were not involved in the procedures. Physicians were allowed to use adjunctive technology as was consistent with their standard of care. The null hypothesis for this study was that patients treated with aspiration as first pass achieve inferior outcomes compared with those treated with a stent retriever first line approach. The primary outcome was non-inferiority of clinical functional outcome at 90 days as measured by the percentage of patients achieving a modified Rankin Scale score of 0-2, analysed by intent to treat; non-inferiority was established with a margin of 0·15. All randomly assigned patients were included in the safety analyses. This trial is registered at ClinicalTrials.gov, number: NCT02466893.

FINDINGS

Between June 1, 2015, and July 5, 2017, we assigned 270 patients to treatment: 134 to aspiration first pass and 136 to stent retriever first line. A modified Rankin score of 0-2 at 90 days was achieved by 69 patients (52%; 95% CI 43·8-60·3) in the aspiration group and 67 patients (50%; 41·6-57·4) in the stent retriever group, showing that aspiration as first pass was non-inferior to stent retriever first line (p_{non-inferiority}=0·0014). Intracranial haemorrhage occurred in 48 (36%) of 134 in the aspiration first pass group, and 46 (34%) of 135 in the stent retriever first line group. All-cause mortality at 3 months occurred in 30 patients (22%) in both groups.

INTERPRETATION

A direct aspiration as first pass thrombectomy conferred non-inferior functional outcome at 90 days compared with stent retriever first line thrombectomy. This study supports the use of direct aspiration as an alternative to stent retriever as first-line therapy for stroke thrombectomy.

FUNDING

Penumbra.

Abstract WP4: Which Characteristics Determine the Decision to Proceed With Endovascular Therapy in Acute Stroke Patients: Results From an International Multidisciplinary Study

Introduction: The current management of acute ischemic stroke has changed recently with the publication of randomized trials using endovascular therapy (EVT).

Rationale/Hypothesis: Limited information is however available on how physicians make decisions regarding patient selection for endovascular therapy (EVT) in the real-world.

Methods: We conducted an international web-based cross-sectional survey of stroke physicians and interventionalists to assess the decision to offer EVT. Part 1 of the survey used hierarchical Bayes’ disaggregate discrete choice modelling to analyze ten pairs of patient scenarios, randomly generated from ten key patient characteristics to have respondents choose which scenario was best suited for EVT in their practice. Part 2 of the survey used mixed effects logistic regression modelling to analyze 22 randomly chosen patient scenarios, again randomly generated from several key patient and hospital level characteristics.

Results: 607 physicians [mean age of 44 (SD 8.5) years, 83.5% men, 53.6% neurologists, 28.7% neuro-interventionists, 13.3% neurosurgeons, 4.7% other], from 38 countries participated. Using disaggregate discrete choice analysis, the most influential characteristic in deciding about EVT was the extent of ischemic change (ASPECTS)/volume of infarct core (26-28% of the choice). Patient age, premorbid status, baseline NIHSS score, and occlusion location (13-15% each) were the other relevant characteristics. Using mixed effects logistic regression, baseline stroke severity (NIHSS> 15 vs. NIHSS 0-5, OR 6.7; 95% CI 4.8-9.5), ASPECTS (5-7 vs. 0-4, OR 9.4; 95% CI7.4-11.9) and occlusion location (distal M2 vs. ICA/M1, OR 012; 95% CI 0.08-0.17) were the most relevant characteristics in deciding about EVT. Time from stroke onset, sex, comorbidities, time of day (off hours vs. day time) were all less relevant in deciding about EVT in both analyses.

Conclusion: Severity of stroke assessed clinically, and extent of brain infarction and location of thrombus assessed on imaging are the dominant characteristics that treating physicians use in the real world when deciding about EVT for patients with an acute ischemic stroke.

Abstract WP37: Real-World Applicability of Thrombectomy in Anterior Circulation Large Vessel Occlusion Strokes Treated in the Extended Window: Analysis of the Prospective Trevo Registry

Background: Two recent trials showed a strong benefit of thrombectomy in the extended window. However, these studies were performed in selected centers and utilized strict inclusion criteria. We aim to evaluate the outcomes of thrombectomy in a large prospective cohort treated outside the rigid clinical trial setting.

Methods: Trevo Registry patients with ICA, MCA-M1 or M2 occlusions and pre-morbid mRS0-2 were categorized according to time-from-last-seen-well (TLSW) to puncture as early (0-6hours) vs. late (6-24hours). Uni- and multivariate analyzes were performed to identify good outcome (90-day mRS0-2) predictors. Subgroup analyses were performed for the basic DAWN (age >=18, NIHSS >=10, ICA or M1 occlusion, pre-morbid mRS 0-1) and DEFUSE 3 (age 18-90, NIHSS >=6, ICA or MCA-M1 occlusion, mRS 0-2) trial criteria.

Results: As compared to the late (n=430), early patients (n=1173) were older (70 vs 68, p=0.011) and had higher IV tPA use (69 vs 25%, p<0.001), lower smoking frequency (33 vs 40%, p=0.011), larger baseline infarcts (21.2 vs 15.6 cc, p=0.045), less frequent ICA occlusions (18 vs 24%, p=0.015), and a trend towards higher admission NIHSS (16 vs 15, p=0.09). Despite significantly longer TLSW to puncture (3.5 vs 9.6 h, p<0.001), late patients had similar rates of mTICI2b-3 (92 vs 94%, p=0.20), good outcomes (60 vs 56%, p=0.128), symptomatic ICH (1.5 vs.1.4%, p=0.84), and 90-day-mortality (10.9 vs.11.4%, p=0.79). Age (OR 0.96, 95%CI [0.96-0.97]), admission-NIHSS (0.91 [0.89-0.93]), baseline mRS (0.49 [0.40-0.60]), ASPECTS >= 6 (1.37 [1.07-1.75]), DM (0.58 [0.44-0.77]), and time to treatment (0.98 [0.97-1.00]) were independent predictors of good outcomes. Imaging modality did not predict outcomes. Similar findings were observed in the early versus late DAWN-like (n=709 vs 257) and DEFUSE 3-like (n=855 vs 273) cohorts. There was great similarity between the outcomes of the Trevo Registry subsets vs their analogous RCTs: early DAWN-like vs SWIFT Prime (90-day mRS 0-2: 57.5 vs 60%; 90-day mRS 6: 11.% vs 9%), Late DAWN-like vs DAWN (50.2 vs 48.6%; 10.6 vs 18%), and Late DEFUSE 3-like vs DEFUSE 3 (52 vs 45%; 10.3 vs 14%).

Conclusions: Our study provides favorable data for the generalizability of the safety and efficacy of thrombectomy in the “real-world” setting.

Standards of practice in acute ischemic stroke intervention: International recommendations

This article was first published in JNIS. Cite this article as: Pierot L, Jayaraman MV, Szikora I, et al. Standards of practice in acute ischemic stroke intervention: international recommendations. Journal of NeuroInterventional Surgery. Published Online First: 28 August 2018. doi: 10.1136/neurintsurg-2018-014287.

ADAPT FAST study: a direct aspiration first pass technique for acute stroke thrombectomy

BACKGROUND

The development of new revascularization devices has improved recanalization rates and time, but not clinical outcomes. We report a prospectively collected clinical experience with a new technique utilizing a direct aspiration first pass technique with large bore aspiration catheter as the primary method for vessel recanalization.

METHODS

98 prospectively identified acute ischemic stroke patients with 100 occluded large cerebral vessels at six institutions were included in the study. The ADAPT technique was utilized in all patients. Procedural and clinical data were captured for analysis.

RESULTS

The aspiration component of the ADAPT technique alone was successful in achieving Thrombolysis in Cerebral Infarction (TICI) 2b or 3 revascularization in 78% of cases. The additional use of stent retrievers improved the TICI 2b/3 revascularization rate to 95%. The average time from groin puncture to at least TICI 2b recanalization was 37 min. A 5MAX demonstrated similar success to a 5MAX ACE in achieving TICI 2b/3 revascularization alone (75% vs 82%, p=0.43). Patients presented with an admitting median National Institutes of Health Stroke Scale (NIHSS) score of 17.0 (12.0-21.0) and improved to a median NIHSS score at discharge of 7.3 (1.0-11.0). Ninety day functional outcomes were 40% (modified Rankin Scale (mRS) 0-2) and 20% (mRS 6). There were two procedural complications and no symptomatic intracerebral hemorrhages.

DISCUSSION

The ADAPT technique is a fast, safe, simple, and effective method that has facilitated our approach to acute ischemic stroke thrombectomy by utilizing the latest generation of large bore aspiration catheters to achieve previously unparalleled angiographic outcomes.

Initial clinical experience with the ADAPT technique: A direct aspiration first pass technique for stroke thrombectomy

BACKGROUND

The development of new revascularization devices has improved recanalization rates and time but not clinical outcomes. We report our initial results with a new technique utilizing a direct aspiration first pass technique with a large bore aspiration catheter as the primary method for vessel recanalization.

METHODS

A retrospective evaluation of a prospectively captured database of 37 patients at six institutions was performed on patients where the ADAPT technique was utilized. The data represent the initial experience with this technique.

RESULTS

The ADAPT technique alone was successful in 28 of 37 (75%) cases although six cases had large downstream emboli that required additional aspiration. Nine cases required the additional use of a stent retriever and one case required the addition of a Penumbra aspiration separator to achieve recanalization. The average time from groin puncture to at least Thrombolysis in Cerebral Ischemia (TICI) 2b recanalization was 28.1 min, and all cases were successfully revascularized. TICI 3 recanalization was achieved 65% of the time. On average, patients presented with an admitting National Institutes of Health Stroke Scale (NIHSS) score of 16.3 and improved to an NIHSS score of 4.2 by the time of hospital discharge. There was one procedural complication.

DISCUSSION

This initial experience highlights the fact that the importance of the technique with which new stroke thrombectomy devices are used may be as crucial as the device itself. The ADAPT technique is a simple and effective approach to acute ischemic stroke thrombectomy. Utilizing the latest generation of large bore aspiration catheters in this fashion has allowed us to achieve excellent clinical and angiographic outcomes.

Computed Tomographic Perfusion Predicts Poor Outcomes in a Randomized Trial of Endovascular Therapy

Background and Purpose—

In the ESCAPE trial (Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion with Emphasis on Minimizing CT to Recanalization Times), patients with large vessel occlusions and small infarct cores identified with computed tomography (CT)/CT angiography were randomized to endovascular therapy or standard of care. CT perfusion (CTP) was obtained in some cases but was not used to select patients. We tested the hypothesis that patients with penumbral CTP patterns have higher rates of good clinical outcome.

Methods—

All CTP data acquired in ESCAPE patients were analyzed centrally using a semiautomated perfusion threshold-based approach. A penumbral pattern was defined as an infarct core <70 mL, penumbral volume >15 mL, and a total hypoperfused volume:core volume ratio of >1.8. The primary outcome was good functional outcome at 90 days (modified Rankin Scale score, 0–2).

Results—

CTP was acquired in 138 of 316 ESCAPE patients. Penumbral patterns were present in 116 of 128 (90.6%) of patients with interpretable CTP data. The rate of good functional outcome in penumbral pattern patients (53 of 114; 46%) was higher than that in nonpenumbral patients (2 of 12; 17%; P =0.041). In penumbral patients, endovascular therapy increased the likelihood of a good clinical outcome (34 of 58; 57%) compared with those in the control group (19 of 58; 33%; odds ratio, 2.68; 95% confidence interval, 1.25–5.76; P =0.011). Only 3 of 12 nonpenumbral patients were randomized to the endovascular group, preventing an analysis of treatment effect.

Conclusions—

The majority of patients with CTP imaging in the ESCAPE trial had penumbral patterns, which were associated with better outcomes overall. Patients with penumbra treated with endovascular therapy had the greatest odds of good functional outcome. Nonpenumbral patients were much less likely to achieve good outcomes.

Comparative safety and efficacy of combined IVT and MT with direct MT in large vessel occlusion

OBJECTIVE

In this multicenter study, we sought to evaluate comparative safety and efficacy of combined IV thrombolysis (IVT) and mechanical thrombectomy (MT) vs direct MT in emergent large vessel occlusion (ELVO) patients.

METHODS

Consecutive ELVO patients treated with MT at 6 high-volume endovascular centers were evaluated. Standard safety and efficacy outcomes (successful reperfusion [modified Thrombolysis in Cerebral Infarction IIb/III], functional independence [FI] [modified Rankin Scale (mRS) score of 0-2 at 3 months], favorable functional outcome [mRS of 0-1 at 3 months], functional improvement [mRS shift by 1-point decrease in mRS score]) were compared between patients who underwent combined IVT and MT vs MT alone. Additional propensity score-matched analyses were performed.

RESULTS

A total of 292 and 277 patients were treated with combination therapy and direct MT, respectively. The combination therapy group had greater functional improvement (p = 0.037) at 3 months. After propensity score matching, 104 patients in the direct MT group were matched to 208 patients in the combination therapy group. IVT pretreatment was independently (p < 0.05) associated with higher odds of FI (odds ratio [OR] 1.75; 95% confidence interval [CI] 1.02-2.99) and functional improvement (common OR 1.64; 95% CI 1.05-2.56). Combination therapy was independently (p < 0.05) related to lower likelihood of 3-month mortality (0.50; 95% CI 0.26-0.96).

CONCLUSIONS

This observational study provides preliminary evidence that IVT pretreatment may improve outcomes in ELVO patients treated with MT. The question of the potential effect of IVT on ELVO patients treated with MT should be addressed with a randomized controlled trial.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that for stroke patients with emergent large vessel occlusion, combined IVT and MT is superior to direct MT in improving functional outcomes.

Abstract 109: Trevo 2000: Results of the Largest Real-World Registry for Stent Retriever for Acute Ischemic Stroke

Objective: The Trevo Registry was designed to assess real world outcomes of the Trevo Retriever in patients experiencing ischemic stroke. It is the largest prospective study for acute stroke intervention, with 2010 patients enrolled and 90 day outcomes in 1873 patients. The primary endpoint is revascularization status based on post-procedure TICI score and secondary endpoints include 90-day mRS, 90-day mortality, neurological deterioration at 24 hours and device/procedure related adverse events.

Methods: The study was a prospective, open-label, consecutive enrollment, multi-center, international registry of patients who underwent mechanical thrombectomy for acute stroke using the Trevo stent retriever as the initial device.

Results: The median NIHSS at admission was 16 (IQR 11-20). Most patients (70.8%) were treated at <= 6 hours from last known normal with a median procedure time of 50 minutes (32-77). The occlusion site was M1 or M2 in 73.9%. General anesthesia was employed in 43.5% of procedures. TICI 2b or 3 revascularization was 92.8% with an average of 1.7 passes with the device. Median NIHSS at 24 hours and discharge was 6 and 4 respectively. Fifty-five percent (55.2%) of patients had mRS ≤2 at 3 months and the overall mortality rate was 13.8%. Patients treated after 8 hours of symptom onset had a 95% revascularization rate and 51.2% mRS ≤2 at 3 months. The symptomatic ICH rate was 1.6%. Patients who met the revised AHA criteria for thrombectomy were found to have 59.5% mRS 0-2 at 90 days.

Conclusions: The Trevo Retriever Registry represents the first real world data with stent retriever use in the era of clinical trials showing the overwhelming benefit of stent retrievers to treat acute ischemic stroke. Due to the fact that this data represents real world use of the Trevo Retriever, (e.g. subjects pre-stroke mRS >1 (29%) and those treated 6-24 hours after stroke symptoms (29%), this data cannot be compared to the results from recent trials with restricted eligibility criteria. Future subgroup analysis of this large cohort will help to identify areas of future research to enhance outcomes further with this treatment modality.

Abstract WP8: Global Real World Evidence of Balloon Guided Stent Retriever Thrombectomy

Background and Aims: Balloon Guide Catheter (BGC) use during thrombectomy treatment in Stroke patients has been reported to have positive effects on revascularization, procedural characteristics, and clinical outcomes. We evaluate the use of BGC in an open-label large prospective TREVO Retriever Registry of real world patients to determine predictors of good ‘clinical’ outcomes.

Method: Consecutive Trevo Registry patients that had Balloon Guide Catheter (BGC) used during their thrombectomy procedure were identified; a subset of patients who fulfilled the criteria (ICA and/or MCA-M1/M2 occlusion with pre-morbid mRS 0-1, TLSW ≤6 hrs) within the cohort were also identified. Multivariate analysis was performed to identify the predictors of good outcomes in BGC thrombectomy patients.

Results: A total of 1031 BGC treated Trevo Registry patients (overall enrolled, n=2010) qualified for analysis, of which 605 patients fulfilling the subset criteria were identified. The mean age of BGC/stent retriever patients was 67.5 with a median (IQR) baseline NIHSS of 15(11-19). Occlusion location of the BCG group was ICA -20.4%, M1- 57.1%, M2/M3-20.3%, and Posterior 1.8%.

In the overall BGC cohort, the median (IQR) time to treatment was (4.2 (3.0,6.5)- hrs.) with conscious/local sedation used in 63.4% and general anesthesia used in 37.3% of cases. The median number of passes with Trevo stent retriever was 1 and revascularization (mTICI ≥ b) was achieved in 92.8% of cases. The sICH rate was low at 1.9% (20/1031) with a low rate of vessel perforation (0.2%). At 90 days post stroke, 56.0% of patients achieved functional independence (mRS 0-2) with 63.7% of the subset of “guidline “ BGC patients achieving functional independence at 90 days. Multivariate logistic regression showed age (aOR 0.97 [0.96, 0.99] P <0.001), Diabetes (aOR 0.67, [0.18,0.98] P =0.03), conscious sedation vs general anesthesia ( aOR 1.7 [1.2,2.3], P= 0.002, number of passes (aOR 0.76 [0.66-0.88],P <0.001), pre stroke mRS (aOR 0.54 [0.45-0.65], P <0.0010 and NIHSS (aOR 0.93 [0.91-0.95], P <0.001) as predictors of functional independence .

Conclusion: Data from Trevo Registry demonstrate the use of BGC in thrombectomy procedure is safe, and leads to a reduction of disability in ischemic stroke patients.

Abstract 112: Identifying Patients Who May Benefit From Thrombectomy in the Late Time Window: Predictors of Good Outcome Beyond Advanced Imaging

Background: The DAWN trial showed EVT effectiveness in the late time window (6-24 hrs), however, DAWN patients were carefully selected based on advanced perfusion imaging, CTP and MRI. Similar to the early window (0-6 hrs), simple imaging (CT) and other clinical variables may select patients for thrombectomy beyond 6 hours. We evaluated a largescale, real world practice for predictors that could identify patients who may benefit from EVT in the late time window.

Methods: Patients with LVO in the anterior circulation (M1, M2, ICA) from a prospective, single arm, multicenter, international registry (Trevo Retriever Registry) treated in the late window LSN to groin puncture (GP) (6-24 hrs) were included. Univariate and multivariate analyses assessed factors independently correlating with good outcome (90 day mRS 0-2). Furthermore, patients outcomes were compared based on their baseline imaging selection CT vs CTP and MRI.

Results: 549 patients were treated beyond 6 hours. The average age was 67, median/IQR ASPECTS 8(6-9), median/IQR NIHSS was 15 (9-20), median/IQR time LSN to GP (hr) was 9.7 (7.3-13.6) and IV-tPA rate were 22.8%. CT was the only imaging selection method in 15.9%, while additional advanced imaging was utilized in the remaining patients; CTP (70%), and MRI(14.1%). Good outcomes were observed in 51.4% of late window patients. Age (aOR 0.96, 95% CI 0.94-0.98, p<0.001), stroke severity by NIHSS (aOR 0.9, 95% CI 0.86-0.95, p<0.001) and ASPECTS (for each point increment in ASPECTS aOR 1.24, 95% CI 1.05-1.47, p=0.012) were independent pre-intervention predictors of good outcome in the late window. The addition of advanced imaging beyond CT, including CTP or MRI, did not confer higher correlation with good outcome (aOR 1.45, 95% CI 0.77-2.73, p=0.25). Good outcome was achieved in 56% of CT selected patients as compared to 53% patients selected by CTP or MRI.

Conclusion: Simple imaging and clinical variables can identify patients that could benefit from thrombectomy in the late window. Importantly, ASPECTS reliably predicted good outcome beyond 6 hours without adjunctive benefit from adding advanced perfusion imaging, a finding that may simplify patients selection to facilitate and generalize the intervention in the late window to wide, real world practice.

Abstract TP29: Endovascular Therapy for Distal Occlusions in the Early and Late Window: an Extension in Location and Time

Background: Endovascular therapy (EVT) effectiveness is established in ischemic strokes with large vessel occlusion (LVO) in the terminal ICA and M1, which was extended up to 24 hrs by recent DAWN trial results. However this benefit is not as well established in more distal (M2) occlusions, especially late presenters (beyond 6 hrs). We evaluated thrombectomy outcomes in M2 occlusions as compared to ICA/M1 across early and late time windows.

Methods: In a prospective, multicenter, single arm, international registry (Trevo Retriever Registry), anterior circulation LVOs were stratified on clot location into M2 vs ICA/M1 and dichotimized into early vs late (0-6 vs 6-24 hrs). 90 day mRS (0-1 excellent, 0-2 good) were the primary outcomes; sICH and dissection were the secondary (safety) outcomes. Multivariate analyses identified pre-procedure variables independently correlating with good outcome in M2s.

Results: 1581 patients were identified (1265 ICA/M1, 316 M2). The M2 and ICA/M1 groups were similar (age in both 68.4), IV-tPA (69.1 vs 69.7%, p=0.8) and same median/IQR ASPECTS 8 (7-9). M2 patients had lower NIHSS (13 vs 16, p<0.001). Higher good and excellent outcomes were observed in M2s (65.8% and 51.3%) compared to ICA/M1 (57.9% and 42.8%) (p=0.01). Similar outcomes were maintained beyond 6 hrs (64.8% good, 45.9% excellent in M2s vs 53.8% and 38.4% in ICA/M1) (p=0.08). Fig 1 shows the probabilities of good outcome in M2 vs ICA/M1 in relation to time, illustrating no association with time (p=0.4). Similar safety profiles were seen: sICH (0% M2 vs 0.7% ICA/M1, p=1.0) and dissections (0.3% M2 vs 0.4% ICA/M1, p=0.22). Age (aOR 0.96, 0.94-0.98 95% CI, p<0.001) and NIHSS (aOR 0.94, 0.9-0.98 95% CI, p<0.001) correlated with good outcome in M2, while IV-tPA did not have adjunctive benefit (aOR 0.72, 0.42-1.24 95% CI, p=0.24).

Conclusion: Excellent and good outcomes may be achieved in distal LVO isolated to M2 similar to those with proximal occlusions. A benefit that can be reached up to 24 hrs.

Abstract WP61: Automated Large Artery Occlusion Detection IN Stroke Imaging - ALADIN Study

Introduction: Acute ischemic stroke (AIS) treatment relies on prompt clinical suspicion, neuroimaging findings and stroke neurologists’ referrals, especially for Large Vessel Occlusion (LVO) patients. Recent advances in artificial intelligence have revolutionized the field of computer vision. We propose the use of artificial-intelligence based algorithm for detection of LVOs in AIS setting.

Methods: We performed a multi-center retrospective analysis of CTAs, randomly picked from a prospective cohort of AIS adult patients, with and without LVOs, admitted at comprehensive stroke centers, from 2014 to 2016. An experienced stroke neurologist graded the CTAs for the presence of occlusion and occlusion sites. Concurrently, studies were analyzed by Viz-AI-Algorithm® v3.04 - a Convolutional Neural Network programed to detect MCA-M1 and/or ICA-T occlusions. The primary analysis included ICA-T and/or MCA-M1 LVOs versus more distal occlusions or no LVOs. The secondary analysis included any ICA and/or MCA-M1 and/or M2 LVOs versus more distal occlusions or no LVOs.

Results: Analysis of 500 CTAs is ongoing and will be fully presented at the ISC. Interim results are available in 152 CTAs (Age, 64.1+/-15.7; bNIHSS 16 [IQR, 10-22]; bASPECTS 8 [IQR, 6-10]). Data was enriched for LVO (82.2%). For the primary analysis, the algorithm obtained sensitivity of 0.97 and specificity of 0.52, with a PPV of 0.74 and NPPV of 0.91, and overall accuracy of 0.78. For the secondary analysis (M2 and proximal ICA included), the algorithm obtained sensitivity of 0.92 and specificity of 0.75, with a PPV of 0.92 and NPPV of 0.75, and overall accuracy of 0.88. Maximal running time of the algorithm was under five minutes.

Conclusion: The Viz-AI-Algorithm performs remarkably well for proximal intracranial LVOs. Endeavors on optimization of MCA-M2 LVO detection are being implemented. To the best of our knowledge, this is the first AI-algorithm for detecting intracranial LVOs.

Abstract WP34: Endovascular Treatment in Large Core Strokes

Introduction: The recent thrombectomy trials were largely limited to patients with small strokes on presentation.

Methods: Patients derived from a large prospective multinational stent-retriever registry (Trevo Registry, n=2,010). Baseline NCCT SPECTS and CTP Core Volumes (rCBF<30%) were adjudicated by a Core Lab. Baseline and outcome variables were compared for ASPECTS 0-5 vs. 6-10 on NCCT and large age-adjusted cores (>70mL if age <=70 years; >50mL if age >70-80 years; >30mL if age >80 years) vs. not on CTP. The primary and secondary efficacy endpoint were the rates of 90-day mRS 0-2 and mTICI 2b-3, respectively. Safety endpoints included sICH and 90-day mortality.

Results: As compared with patients with higher baseline ASPECTS (n=1037), low baseline ASPECTS (0-4, n=78; 5, n=78) patients were younger, had higher stroke severity, and tend to have less comorbidities and undergo thrombectomy at later times (Table 1a). TICI-3 reperfusion was higher in the higher-ASPECTS group but other reperfusion outcomes were nearly the same. Safety outcomes were comparable. Rates of 90-day mRS 0-2 were significantly higher in the high-ASPECTS group (p<0.001); however, 41.8% of ASPECTS 0-5 patients were independent at 90 days and safety outcomes were similar (Table 1b). Analysis according to large age-adjusted core (n=86) vs not (n=431) yielded similarly encouraging results (Table 2a-b).

Conclusion: Patients with large baseline cores as measured by either NCCT or CTP may still achieve favorable outcomes with endovascular treatment. A randomized clinical trial in this patient population is warranted.

Abstract 107: Real World Clinical and Radiographic Outcomes With and Without Intravenous tPA in Anterior Circulation Large Vessel Occlusion Mechanical Thrombectomy Patients Treated Within 8 Hours

Background and Aims: Intravenous tPA remains the standard of care, with MT currently indicated within 8 hours for IV tPA failures or patients with IV tPA contraindications. Whether LVO patients should receive IV tPA treatment or instead be triaged directly to MT therapy is currently unknown but greatly debated. The Trevo Registry is a real world, multi-center, international study of mechanical thrombectomy (MT) patients treated from 0-24 hours. Evaluation of the Trevo Registry clinical and procedurals outcomes of MT patients treated with or without IV tPA could provide insight into the benefit of IV tPA in MT patients. We hypothesized that in MT patients treated within 8 hours, pretreatment with intravenous tPA would lead to better clinical outcomes compared to patients who did not receive IV tPA.

Method: Consecutively enrolled patients treated within 8 hours with ICA, M1, or M2 occlusions were selected for analysis. Univariate and multivariable regressions were conducted to identify clinical and radiographic independent variables that correlate best with the dependent variable of functional outcome: mRS 0-2, with a focus on intravenous tPA treatment.

Results: A total of 1183 Trevo Registry patients (overall enrolled, n=2010) qualified for analysis, of whom 380 were not treated with IV tPA. Demographics were similar, however atrial fibrillation (46.3% vs 27.2%) and previous ischemic stroke (14.1% vs 7.5%) were higher in the no IV tPA group. The median time to treatment was similar (3.8 vs. 3.6 hrs). First pass mTICI ≥ 2B (63.6% vs 66.4%) and final revascularization (91.1% vs 92.8%) were similar between no IV tPA and IV tPA groups.Unadjusted, there were similar rates of functional outcome (90 day mRS 0-2; 60.9% vs. 62.5%). After adjustment, patients who did not receive IV-tPA had similar rates of good outcome (aOR 1.08, 95% CI [0.87-1.34]. P=0.58) as well as reduction (shift) in disability (aOR 1.08, 95% CI [0.87-1.34]. P=0.49). Safety outcomes (mortality, sICH) were similar between both groups.

Conclusion: In the Trevo Registry of MT patients treated within 8 hours, patients who did not receive IV tPA had similar endovascular and clinical outcomes as patients pretreated with IV tPA. The added benefit of IV tPA for MT patients should be further investigated.

Abstract TP26: Endovascular Therapy in Patients With Low NIHSS Score on Presentation

Introduction: Approximately 2/3 of all AIS present with NIHSS 0-5. While it has been demonstrated that LVO can be found in ~10-20% of all low NIHSS patients, outcome data in this population remains scarce. Indeed, only 14/1766 patients in the recent endovascular RCTs had baseline (b) NIHSS in the 0-5 range. Yet, the presence of LVO in the setting of low NIHSS is associated with ~10-fold increase in subsequent deterioration. We aim to describe the outcomes in a large cohort of low NIHSS patients undergoing thrombectomy.

Methods: Patients derived from a large prospective multicenter international stent-retriever registry (Trevo Registry, n=2,010). Baseline and outcome variables were compared according to bNIHSS 0-8 vs >8 and bNIHSS 0-5 vs >5. The primary and secondary efficacy endpoints were the rates of 90-day mRS 0-2 and mTICI 2b-3, respectively. Safety endpoints included sICH and 90-day mortality.

Results: A total of 1,985 patients were included. As compared with patients with higher baseline NIHSS, low baseline NIHSS (0-8, n=342; 0-5, n=160) patients were younger, had less comorbidities and better functional status, more frequently had MCA-M2 or vertebrobasilar occlusions, less frequently received IV tpa, and underwent thrombectomy at later times (Table 1). The reperfusion outcomes were nearly the same. There were no significant differences in procedure-related complications, which were overall low (Table 2). The rates of 90-day mRS 0-2 were significantly higher in the lower NIHSS patients (p<0.001); however, ~20% of those patients were not independent and ~7% were dead at 90 days despite presenting with low clinical severity.

Conclusion: Despite safe and efficacious endovascular reperfusion, low-NIHSS LVO patients have a relatively high proportion of bad outcomes. This supports the notion that many of "mildly" presenting patients do not fare well. A randomized clinical trial including immediate endovascular treatment in this patient population is warranted.

Correlation of imaging and histopathology of thrombi in acute ischemic stroke with etiology and outcome: a systematic review

BACKGROUND AND PURPOSE

Studying the imaging and histopathologic characteristics of thrombi in ischemic stroke could provide insights into stroke etiology and ideal treatment strategies. We conducted a systematic review of imaging and histologic characteristics of thrombi in acute ischemic stroke.

MATERIALS AND METHODS

We identified all studies published between January 2005 and December 2015 that reported findings related to histologic and/or imaging characteristics of thrombi in acute ischemic stroke secondary to large vessel occlusion. The five outcomes examined in this study were (1) association between histologic composition of thrombi and stroke etiology; (2) association between histologic composition of thrombi and angiographic outcomes; (3) association between thrombi imaging and histologic characteristics; (4) association between thrombi imaging characteristics and angiographic outcomes; and (5) association between imaging characteristics of thrombi and stroke etiology. A meta-analysis was performed using a random effects model.

RESULTS

There was no significant difference in the proportion of red blood cell (RBC)-rich thrombi between cardioembolic and large artery atherosclerosis etiologies (OR 1.62, 95% CI 0.1 to 28.0, p=0.63). Patients with a hyperdense artery sign had a higher odds of having RBC-rich thrombi than those without a hyperdense artery sign (OR 9.0, 95% CI 2.6 to 31.2, p<0.01). Patients with a good angiographic outcome had a mean thrombus Hounsfield unit (HU) of 55.1±3.1 compared with a mean HU of 48.4±1.9 for patients with a poor angiographic outcome (mean standard difference 6.5, 95% CI 2.7 to 10.2, p<0.001). There was no association between imaging characteristics and stroke etiology (OR 1.13, 95% CI 0.32 to 4.00, p=0.85).

CONCLUSIONS

The hyperdense artery sign is associated with RBC-rich thrombi and improved recanalization rates. However, there was no association between the histopathological characteristics of thrombi and stroke etiology and angiographic outcomes.

Diffusion-weighted imaging or computerized tomography perfusion assessment with clinical mismatch in the triage of wake up and late presenting strokes undergoing neurointervention with Trevo (DAWN) trial methods

Rationale Efficacy of mechanical thrombectomy for acute stroke due to large vessel occlusion initiated beyond 6 h of time last seen well has not been demonstrated in randomized trials. Aim To establish whether subjects considered to have substantial areas of salvageable brain based on age-adjusted clinical core mismatch who can undergo endovascular treatment within 6-24 h from time last seen well (TLSW) have better outcomes at three months compared to subjects treated with standard medical therapy alone. Age-adjusted clinical core mismatch is defined by age (≤80 or >80 years), baseline National Institutes of Health Stroke Scale (NIHSS) (10-20 or ≥21), and core size (0-20 cm³ in subjects older than 80 and, in subjects younger than 80, 0-30 cm³ with NIHSS 10-20 and 31-50 cm³ with NIHSS ≥21). Design Prospective, randomized, multicenter, Bayesian adaptive-enrichment, open label trial with blinded endpoint assessment. For the purpose of enrolment, ischemic core size will be evaluated by CT perfusion or magnetic resonance imaging-diffusion-weighted imaging measured by automated software (RAPID). Procedures Subjects with acute ischemic stroke due to computed tomography angiography- or magnetic resonance angiogram-proven arterial occlusion of the intracranial internal carotid and/or proximal middle cerebral artery (M1) with age-adjusted clinical core mismatch in whom treatment can be initiated between 6 and 24 h from TSLW are randomized in a 1:1 ratio to receive mechanical embolectomy with the Trevo device or medical management alone. Sequential interim analyses allowing adaptation of enrolment criteria or stopping new enrolment for futility or predicted success will occur in every 50 randomized patients starting at 150 to a maximum of 500 patients. Study outcomes The primary endpoint is the modified Rankin Scale score at 90 days. The primary safety outcome is stroke-related mortality at 90 days. Analysis The primary endpoint, expressed as a utility-weighted modified Rankin Scale score is analyzed using a Bayesian posterior probability with adjustment for ischemic core size. For regulatory reasons, a nested co-primary endpoint analysis was added consisting of the proportion of subjects with modified Rankin Scale 0-2 between the active and control groups also analyzed using a Bayesian model.

Analyses of thrombi in acute ischemic stroke: A consensus statement on current knowledge and future directions

Limited data exist on clot composition and detailed characteristics of arterial thrombi associated with large vessel occlusion in acute ischemic stroke. Advances in endovascular thrombectomy and related imaging modalities have created a unique opportunity to analyze thrombi removed from cerebral arteries. Insights into thrombus composition, etiology, physical properties and neurovascular interactions may lead to future advancements in acute ischemic stroke treatment and improved clinical outcomes. Advances in imaging techniques may enhance clot characterization and inform therapeutic decision-making prior to treatment and reveal stroke etiology to guide secondary prevention. Current imaging techniques can provide some information about thrombi, but there remains much to evaluate about relationships that may exist among thrombus composition, occlusion characteristics and treatment outcomes. Improved pathophysiological characterization of clot types, their properties and how these properties change over time, together with clinical correlates from ongoing studies, may facilitate revascularization with thrombolysis and thrombectomy. Interdisciplinary approaches covering clinical, engineering and scientific aspects of thrombus research will be key to advancing the understanding of thrombi and improving acute ischemic stroke therapy. This consensus statement integrates recent research on clots and thrombi retrieved from cerebral arteries and provides a rationale for further analyses, including current opportunities and limitations.