Endovascular Thrombectomy for Large Ischemic Stroke Across Ischemic Injury and Penumbra Profiles

Importance

Whether endovascular thrombectomy (EVT) efficacy for patients with acute ischemic stroke and large cores varies depending on the extent of ischemic injury is uncertain.

Objective

To describe the relationship between imaging estimates of irreversibly injured brain (core) and at-risk regions (mismatch) and clinical outcomes and EVT treatment effect.

Design, Setting, and Participants

An exploratory analysis of the SELECT2 trial, which randomized 352 adults (18-85 years) with acute ischemic stroke due to occlusion of the internal carotid or middle cerebral artery (M1 segment) and large ischemic core to EVT vs medical management (MM), across 31 global centers between October 2019 and September 2022.

Intervention

EVT vs MM.

Main Outcomes and Measures

Primary outcome was functional outcome-90-day mRS score (0, no symptoms, to 6, death) assessed by adjusted generalized OR (aGenOR; values >1 represent more favorable outcomes). Benefit of EVT vs MM was assessed across levels of ischemic injury defined by noncontrast CT using ASPECTS score and by the volume of brain with severely reduced blood flow on CT perfusion or restricted diffusion on MRI.

Results

Among 352 patients randomized, 336 were analyzed (median age, 67 years; 139 [41.4%] female); of these, 168 (50%) were randomized to EVT, and 2 additional crossover MM patients received EVT. In an ordinal analysis of mRS at 90 days, EVT improved functional outcomes compared with MM within ASPECTS categories of 3 (aGenOR, 1.71 [95% CI, 1.04-2.81]), 4 (aGenOR, 2.01 [95% CI, 1.19-3.40]), and 5 (aGenOR, 1.85 [95% CI, 1.22-2.79]). Across strata for CT perfusion/MRI ischemic core volumes, aGenOR for EVT vs MM was 1.63 (95% CI, 1.23-2.16) for volumes ≥70 mL, 1.41 (95% CI, 0.99-2.02) for ≥100 mL, and 1.47 (95% CI, 0.84-2.56) for ≥150 mL. In the EVT group, outcomes worsened as ASPECTS decreased (aGenOR, 0.91 [95% CI, 0.82-1.00] per 1-point decrease) and as CT perfusion/MRI ischemic core volume increased (aGenOR, 0.92 [95% CI, 0.89-0.95] per 10-mL increase). No heterogeneity of EVT treatment effect was observed with or without mismatch, although few patients without mismatch were enrolled.

Conclusion and Relevance

In this exploratory analysis of a randomized clinical trial of patients with extensive ischemic stroke, EVT improved clinical outcomes across a wide spectrum of infarct volumes, although enrollment of patients with minimal penumbra volume was low. In EVT-treated patients, clinical outcomes worsened as presenting ischemic injury estimates increased.

Trial Registration

ClinicalTrials.gov Identifier: NCT03876457.

Endovascular thrombectomy plus medical care versus medical care alone for large ischaemic stroke: 1-year outcomes of the SELECT2 trial

BACKGROUND

Multiple randomised trials have shown efficacy and safety of endovascular thrombectomy in patients with large ischaemic stroke. The aim of this study was to evaluate long-term (ie, at 1 year) evidence of benefit of thrombectomy for these patients.

METHODS

SELECT2 was a phase 3, open-label, international, randomised controlled trial with blinded endpoint assessment, conducted at 31 hospitals in the USA, Canada, Spain, Switzerland, Australia, and New Zealand. Patients aged 18-85 years with ischaemic stroke due to proximal occlusion of the internal carotid artery or of the first segment of the middle cerebral artery, showing large ischaemic core on non-contrast CT (Alberta Stroke Program Early Computed Tomographic Score of 3-5 [range 0-10, with lower values indicating larger infarctions]) or measuring 50 mL or more on CT perfusion and MRI, were randomly assigned, within 24 h of ischaemic stroke onset, to thrombectomy plus medical care or to medical care alone. The primary outcome for this analysis was the ordinal modified Rankin Scale (range 0-6, with higher scores indicating greater disability) at 1-year follow-up in an intention-to-treat population. The trial is registered at ClinicalTrials.gov (NCT03876457) and is completed.

FINDINGS

The trial was terminated early for efficacy at the 90-day follow-up after 352 patients had been randomly assigned (178 to thrombectomy and 174 to medical care only) between Oct 11, 2019, and Sept 9, 2022. Thrombectomy significantly improved the 1-year modified Rankin Scale score distribution versus medical care alone (Wilcoxon-Mann-Whitney probability of superiority 0·59 [95% CI 0·53-0·64]; p=0·0019; generalised odds ratio 1·43 [95% CI 1·14-1·78]). At the 1-year follow-up, 77 (45%) of 170 patients receiving thrombectomy had died, compared with 83 (52%) of 159 patients receiving medical care only (1-year mortality relative risk 0·89 [95% CI 0·71-1·11]).

INTERPRETATION

In patients with ischaemic stroke due to a proximal occlusion and large core, thrombectomy plus medical care provided a significant functional outcome benefit compared with medical care alone at 1-year follow-up.

FUNDING

Stryker Neurovascular.

Trial of Endovascular Thrombectomy for Large Ischemic Strokes

BACKGROUND

Trials of the efficacy and safety of endovascular thrombectomy in patients with large ischemic strokes have been carried out in limited populations.

METHODS

We performed a prospective, randomized, open-label, adaptive, international trial involving patients with stroke due to occlusion of the internal carotid artery or the first segment of the middle cerebral artery to assess endovascular thrombectomy within 24 hours after onset. Patients had a large ischemic-core volume, defined as an Alberta Stroke Program Early Computed Tomography Score of 3 to 5 (range, 0 to 10, with lower scores indicating larger infarction) or a core volume of at least 50 ml on computed tomography perfusion or diffusion-weighted magnetic resonance imaging. Patients were assigned in a 1:1 ratio to endovascular thrombectomy plus medical care or to medical care alone. The primary outcome was the modified Rankin scale score at 90 days (range, 0 to 6, with higher scores indicating greater disability). Functional independence was a secondary outcome.

RESULTS

The trial was stopped early for efficacy; 178 patients had been assigned to the thrombectomy group and 174 to the medical-care group. The generalized odds ratio for a shift in the distribution of modified Rankin scale scores toward better outcomes in favor of thrombectomy was 1.51 (95% confidence interval [CI], 1.20 to 1.89; P<0.001). A total of 20% of the patients in the thrombectomy group and 7% in the medical-care group had functional independence (relative risk, 2.97; 95% CI, 1.60 to 5.51). Mortality was similar in the two groups. In the thrombectomy group, arterial access-site complications occurred in 5 patients, dissection in 10, cerebral-vessel perforation in 7, and transient vasospasm in 11. Symptomatic intracranial hemorrhage occurred in 1 patient in the thrombectomy group and in 2 in the medical-care group.

CONCLUSIONS

Among patients with large ischemic strokes, endovascular thrombectomy resulted in better functional outcomes than medical care but was associated with vascular complications. Cerebral hemorrhages were infrequent in both groups. (Funded by Stryker Neurovascular; SELECT2 ClinicalTrials.gov number, NCT03876457.).

Abstract 24: Primary Results Of The Preset For Occlusive Stroke Treatment (prost) Randomized Clinical Trial

Importance: Clinical trials focusing on new mechanical thrombectomy (MT) technologies have been typically single-arm studies using historical comparison data to determine the safety and efficacy of the novel device. To date, there has not been a contemporaneous prospective, randomized, controlled study comparing standard to newer designed stent-retrievers.

Objective: To evaluate the safety and efficacy of the pRESET (phenox Ltd) compared to the Solitaire (Medtronic Corp) thrombectomy devices in the treatment of large vessel occlusion strokes (LVOS).

Methods: Multicenter, prospective, randomized, open-label, blinded endpoint, core lab adjudicated, non-inferiority trial that enrolled 340 patients from October 2019 to February 2022 across 19 US & 5 German sites. Patients aged ≥ 18 years with either anterior or posterior circulation LVOS were included up to 8 hours after symptom onset. Patients were randomly assigned in a 1:1 ratio to either pRESET or Solitaire for the first three device passes.The Primary Endpoint was the proportion of patients achieving a modified Rankin Scale score of 0-2, analyzed by intent to treat with a non-inferiority margin of 0.125 based on the lower bound 95% Confidence Interval. The Primary Safety Endpoint was the proportion of subjects with device- or procedure-related symptomatic intracerebral hemorrhage at 24 (-8/+12) hours as per the SITS-MOST criteria. Secondary Outcome Measures included the rates of (1) Successful Revascularization (defined as expanded Thrombolysis in Cerebrovascular Infarction [eTICI] ≥2b50 ≤3 passes of the assigned device; (2) eTICI ≥2c following the first pass of the assigned device; (3) 90-day mortality and (4) Distribution of 90-day mRS across the entire spectrum of disability (ordinal shift).

Results: The study database was locked in August 2022. The analysis is ongoing and the final results will be presented at the 2023 International Stroke Conference.

Conclusions and Relevance: PROST is the first randomized clinical trial aiming to compare a novel versus an established stent-retriever technology, establishing a new scientific benchmark for stroke device trials. (ClinicalTrials.gov: NCT03994822).

Abstract P481: Time to Reperfusion Determines Clinical Outcomes Independent of Post Thrombectomy Infarct Volume

Introduction: Late time window thrombectomy trials demonstrated that good functional outcomes can be achieved up to 24 hours from stroke onset in Slow Progressors (small infarct volume and large penumbral volume). In this study, we aim to investigate whether early (<6 hours) recanalization leads to superior functional outcomes compared to delayed recanalization (>6 hours) amongst patients with similar 24-hour infarct volumes post thrombectomy.

Methods: We performed a retrospective analysis of a prospectively maintained LVO stroke thrombectomy database across 3 comprehensive stroke centers. Demographic, clinical, radiological, and outcomes data were analyzed. Inclusion criteria were witnessed onset anterior circulation LVO [internal carotid or middle cerebral artery M1] strokes with a good baseline mRS score (0-1) having achieved success recanalization [mTICI 2b-3] and 24-hour infarct volume of ≤10 ml on CT head or MRI. Univariate and multivariate analysis of the impact of time to recanalization on clinical outcomes was performed.

Results: Of the 499 LVO strokes undergoing thrombectomy, 30% (148) met inclusion criteria. Mean age was 70 ±14 and median NIHSS score was 17 (14-21). Early recanalization (<6h) was achieved in 65% (96) of patients. Baseline demographic (age: 73 vs 74, p=0.80) and clinical characteristics (NIHSS:16.5 vs 17, p=0.52; 24-h infarct volume: 4.4 vs 4.2 ml, p=0.60) were comparable between early versus late recanalization patients. Rates of early clinical improvement (24-h NIHSS <6) (71% vs 39%, p=0.0007) and mRS 0-2 at 90 days (68% vs 48%, p=0.019) were higher in early recanalizers compared to late recanalizers. Multivariate analysis including age, NIHSS, time to recanalization, and 24-hour infarct volume identified early recanalization as an independent predictor of mRS 0-2 at 90 days (OR-2.41 95% CI 1.89-4.50). Every 1-hour increase in time to recanalization decreased the odds of 90-day mRS 0-2 by 2.2%.

Conclusion: Among patients with similar 24-hour infarct volume post thrombectomy (≤10 ml), shorter time to successful recanalization is associated with significantly higher rates of early clinical improvement and mRS 0-2 at 90 days. Increased penumbral ischemic time may have an impact on outcomes post stroke thrombectomy.

Abstract WP6: Successful Mechanical Thrombectomy Maybe Associated With Reduced Disability in Patients With Large Core Based on CTP: The Forsaken Cannot be Forgotten

Background and Purpose: There is disparity on neuroimaging selection for acute stroke thrombectomy. Patients with large core infarcts are often excluded from reperfusion therapies. We aim to assess rates of favorable clinical outcomes in patients with large cores based on CTP (RAPID) and the effect of collaterals in this population.

Methods: Retrospective study of patients with ischemic cores greater than 50cc on CTP and a proximal anterior circulation occlusion on computed tomographic angiogram who underwent endovascular thrombectomy. Evaluation period was October 2015 to June 2018 on three comprehensive stroke centers. Baseline characteristics, ASPECTS and collaterals scores were evaluated. Primary endpoint was rate of favorable clinical outcome at 3 months.

Results: 45 patients were included in the study. Mean age was 65 ±14.2 years, mean NIHSS score was 20 (10-32) and mean admission infarct volume was 85±31mL (CBF <30%) and Tmax>6 s was 199.5±68mL. The majority of patients presented within 6 hours (82%). Median ASPECTS score was 8 and 33% of patients had a favorable collaterals. Recanalization thrombolysis in cerebral ischemia 2b-3 was 88%. Post-thrombectomy mean infarct volume at 24 to 48 hours was 107±68.3mL, A total of 42% (19/45) had tPA. A 3-month favorable clinical outcome (mRS 0-2) was present in 31% (14/45) of patients. Rate of intracranial hemorrhage (ph1 or ph2) was 11% (5/45). A total of 92% (13/14) of all patients older than 75 years had a poor clinical outcome (mRS score >2). Among patients with good collaterals 46% (7/15) had good clinical outcomes whereas 23% (7/30) of patients with poor collaterals score had good clinical outcomes at 3 months. The rate of good outcome at three months for patients with ASPECTS> 6 was 31% (11/35), while 41% of patients with both favorable ASPECTS and Collaterals had a good clinical outcome. Hemicraniectomy was performed in 4% (2/45) of all patients.

Conclusions: Acute stroke thrombectomy may be beneficial in some patients with large core based on CTP with good collaterals and it should not be withhold solely based on the core infarct volume on CTP in patients presenting within 6 hours.