SELECTion criteria for large core trials: dogma or data?

Thrombectomy in ischemic stroke patients with large core but minor ischemic changes on non-enhanced computed tomography

PURPOSE

The Alberta Stroke Program Early CT Score (ASPECTS) is regularly used to guide patient selection for mechanical thrombectomy (MT). Similarly, penumbral imaging based on computed tomography perfusion (CTP) may serve as neuroimaging tool to guide treatment. Yet, patients with a large ischemic core on CTP may show only minor ischemic changes resulting in a high ASPECTS.

AIM

We hypothesized twofold: (1) the treatment effect of vessel recanalization in patients with core volume > 50 mL but ASPECTS ⩾ 6 is not different compared to high ASPECTS patients with core volume < 50 mL, and (2) recanalization is associated with core overestimation.

METHODS

We conducted an observational study analyzing ischemic stroke patients consecutively treated with MT after triage by multimodal CT. Functional endpoint was the rate of functional independence at Day 90 defined as modified Rankin Scale (mRS) 0-2. Imaging endpoint was core overestimation, which was considered when CTP-derived core was larger than the final infarct volume assessed on follow-up imaging. Recanalization was evaluated with the extended Thrombolysis in Cerebral Infarction (eTICI) scale. Multivariable logistic regression analysis and propensity score matching (PSM) were used to assess the association of recanalization (eTICI ⩾ 2b) with functional outcome and core overestimation.

RESULTS

Of 630 patients with ASPECTS ⩾ 6, 91 patients (14.4%) had a large ischemic core. Following 1:1 PSM, the treatment effect of recanalization was not different in patients with large core and ASPECTS ⩾ 6 (+ 25.8%, 95% CI: 16.3-35.4, p < 0.001) compared to patients with ASPECTS ⩾ 6 and core volume < 50 mL (+ 14.9%, 95% CI: 5.7-24.1, p = 0.002). Recanalization (aOR: 3.46, 95% CI: 1.85-6.47, p < 0.001) and higher core volume (aOR: 1.03, 95% CI: 1.02-1.04, p < 0.001) were significantly associated with core overestimation.

CONCLUSION

In patients with ASPECTS ⩾ 6, core volumes did not significantly modify outcomes following recanalization. Reperfusion and higher core volume were significantly associated with core overestimation which may explain the treatment effect of MT for patients with a large ischemic core but minor ischemic changes on non-enhanced CT.

DATA ACCESS STATEMENT

The data analyzed in this study will be available and shared on reasonable request from any qualified researcher for the purpose of replicating the results after clearance by the local ethics committee.

Thrombectomy in Patients With Ischemic Stroke Without Salvageable Tissue on CT Perfusion

BACKGROUND

Computed tomography perfusion (CTP) imaging is regularly used to guide patient selection for mechanical thrombectomy (MT). However, the effect of MT in patients without salvageable tissue on CTP has not been investigated. The purpose of this study was to assess the effect of MT in patients with stroke without perfusion mismatch profiles.

METHODS

This observational study analyzed patients with ischemic stroke consecutively treated between March 1, 2015, and January 31, 2022, triaged by multimodal-computed tomography undergoing MT. CTP lesion-core mismatch profiles were defined using a mismatch volume/ratio of ≥10 mL/1.2, respectively. The primary end point was the rate of functional independence at 90 days, defined as the modified Rankin Scale score of 0 to 2. Recanalization was evaluated with the modified Thrombolysis in Cerebral Infarction scale. The effect of baseline variables on functional outcome was assessed using multivariable logistic regression analysis. Outcomes of patients with and without CTP-mismatch profiles were compared using 1:1 propensity score matching.

RESULTS

Of 724 patients who met the inclusion criteria of this retrospective observational study, 110 (15%) patients had no CTP mismatch and were analyzed. The median age was 74 (interquartile range, 62-80) years and 53% were women. Successful recanalization (modified Thrombolysis in Cerebral Infarction score, ≥2b) was achieved in 66% (73) and associated with functional independence at 90 days (adjusted odds ratio, 7.33 [95% CI, 1.22-43.70]; P=0.03). A significant interaction was observed between recanalization and age, as well as the extent of infarction, indicating MT to be most effective in patients <70 years and with a baseline Alberta Stroke Program Early Computed Tomography Score range between 3 and 7. These findings remained stable after propensity score matching, analyzing 152 matched pairs with similar rates of functional independence between patients with and without CTP-mismatch profiles (17% versus 23%; P=0.42).

CONCLUSIONS

In patients without CTP-mismatch profiles defined according to the EXTEND (Extending the Time for Thrombolysis in Emergency Neurological Deficits) criteria, recanalization was associated with improved functional outcomes. This effect was associated with baseline Alberta Stroke Program Early Computed Tomography Score and age, but not with the time from onset to imaging.

Alberta Stroke Program Early Computed Tomography Score, Infarct Core Volume, and Endovascular Therapy Outcomes in Patients With Large Infarct: A Secondary Analysis of the ANGEL-ASPECT Trial

Importance

Endovascular therapy (EVT) demonstrated better outcomes compared with medical management in recent randomized clinical trials (RCTs) of patients with large infarct.

Objective

To compare outcomes of EVT vs medical management across different strata of the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) and infarct core volume in patients with large infarct.

Design, Setting, and Participants

This prespecified secondary analysis of subgroups of the Endovascular Therapy in Acute Anterior Circulation Large Vessel Occlusive Patients With a Large Infarct Core (ANGEL-ASPECT) RCT included patients from 46 stroke centers across China between October 2, 2020, and May 18, 2022. Participants were enrolled within 24 hours of symptom onset and had ASPECTS of 3 to 5 or 0 to 2 and infarct core volume of 70 to 100 mL. Patients were divided into 3 groups: ASPECTS of 3 to 5 with infarct core volume less than 70 mL, ASPECTS of 3 to 5 with infarct core volume of 70 mL or greater, and ASPECTS of 0 to 2.

Interventions

Endovascular therapy or medical management.

Main Outcomes and Measures

The primary outcome was the ordinal 90-day modified Rankin Scale (mRS) score.

Results

There were 455 patients in the trial; median age was 68 years (IQR, 60-73 years), and 279 (61.3%) were male. The treatment effect did not vary significantly across the 3 baseline imaging subgroups (P = .95 for interaction). The generalized odds ratio for the shift in the 90-day mRS distribution toward better outcomes with EVT vs medical management was 1.40 (95% CI, 1.06-1.85; P = .01) in patients with ASPECTS of 3 to 5 and infarct core volume less than 70 mL, 1.22 (95% CI, 0.81-1.83; P = .23) in patients with ASPECTS of 3 to 5 and infarct core volume of 70 mL or greater, and 1.59 (95% CI, 0.89-2.86; P = .09) in patients with ASPECTS of 0 to 2.

Conclusions and Relevance

In this study, no significant interaction was found between baseline imaging status and the benefit of EVT compared with medical management in patients with large infarct core volume. However, estimates within subgroups were underpowered. A pooled analysis of large core trials stratified by ASPECTS and infarct core volume strata is warranted.

Trial Registration

ClinicalTrials.gov Identifier: NCT04551664.

Penumbra salvage in extensive stroke: exploring limits for reperfusion therapy

BACKGROUND

The effect of thrombectomy in patients presenting with extensive ischemic stroke at baseline is currently being investigated; it remains uncertain to what extent brain tissue may be saved by reperfusion in such patients. Penumbra salvage volume (PSV) has been described as a tool to measure the volume of rescued penumbra.

OBJECTIVE

To assess whether the effect of recanalization on PSV is dependent on the extent of early ischemic changes.

METHODS

Observational study of patients with anterior circulation ischemic stroke triaged by multimodal-CT undergoing thrombectomy. PSV was defined as the difference between baseline penumbra volume and net infarct growth to follow-up. The effect of vessel recanalization on PSV depending on the extent of early ischemic changes (defined using Alberta Stroke Program Early CT Score (ASPECTS) and core volumes based on relative cerebral blood flow) was determined using multivariable linear regression analysis, and the association with functional outcome at day 90 was tested using multivariable logistic regression.

RESULTS

384 patients were included, of whom 292 (76%) achieved successful recanalization (modified Thrombolysis in Cerebral Infarction ≥2b). Successful recanalization was independently associated with 59 mL PSV (95% CI 29.8 to 88.8 mL) and was linked to increased penumbra salvage up to an ASPECTS of 3 and core volume up to 110 mL. Recanalization was associated with a higher probability of a modified Rankin Scale score of ≤2 up to a core volume of 100 mL.

CONCLUSIONS

Recanalization was associated with significant penumbra salvage up to a lower ASPECTS margin of 3 and upper core volume margin of 110 mL. The clinical benefit of recanalization for patients with very large ischemic regions of >100 mL or ASPECTS <3 remains uncertain and requires prospective investigation.

Current and Emerging Endovascular and Neurocritical Care Management Strategies in Large-Core Ischemic Stroke

The volume of infarcted tissue in patients with ischemic stroke is consistently associated with increased morbidity and mortality. Initial studies of endovascular thrombectomy for large-vessel occlusion excluded patients with established large-core infarcts, even when large volumes of salvageable brain tissue were present, due to the high risk of hemorrhagic transformation and reperfusion injury. However, recent retrospective and prospective studies have shown improved outcomes with endovascular thrombectomy, and several clinical trials were recently published to evaluate the efficacy of endovascular management of patients presenting with large-core infarcts. With or without thrombectomy, patients with large-core infarcts remain at high risk of in-hospital complications such as hemorrhagic transformation, malignant cerebral edema, seizures, and others. Expert neurocritical care management is necessary to optimize blood pressure control, mitigate secondary brain injury, manage cerebral edema and elevated intracranial pressure, and implement various neuroprotective measures. Herein, we present an overview of the current and emerging evidence pertaining to endovascular treatment for large-core infarcts, recent advances in neurocritical care strategies, and their impact on optimizing patient outcomes.

Current advances in endovascular treatment

PURPOSE OF REVIEW

Endovascular thrombectomy (EVT) is the most beneficial reperfusion therapy for acute ischemic stroke. Currently, much effort is done to promote trials examining EVT efficacy and safety in various conditions not included in the main randomized controlled trials established the superiority of EVT. This review summarizes the current advances of EVT patients' selection and periprocedural management.

RECENT FINDINGS

Recent evidence points to beneficial effect of EVT among patients with relatively large ischemic core, premorbid independent nonagenarians and basilar artery occlusion, and suggest that intravenous thrombolysis bridging treatment is associated with better reperfusion rates. Ongoing trials currently examine EVT efficacy and safety in distal vessel occlusions and in large vessel occlusion with low NIHSS. Current evidence also support use of general anaesthesia and avoid postprocedural extremely low or high blood pressure as well as haemodynamic instability.

SUMMARY

The field of EVT is rapidly evolving. The results of recent trials have dramatically increased the indications for EVT, with many ongoing trials examining further indications.

Association of Endovascular Thrombectomy With Functional Outcome in Patients With Acute Stroke With a Large Ischemic Core

BACKGROUND AND OBJECTIVES

Endovascular thrombectomy (EVT) is effective for patients with large vessel occlusion (LVO) stroke with smaller volumes of CT perfusion (CTP)-defined ischemic core. However, the benefit of EVT is unclear in those with a core volume >70 mL. We aimed to compare outcomes of EVT and non-EVT patients with an ischemic core volume ≥70 mL, hypothesizing that there would be a benefit from EVT for fair outcome (3-month modified Rankin scale [mRS] 0-3) after stroke.

METHODS

A retrospective analysis of patients enrolled into a multicenter (Australia, China, and Canada) registry (2012-2020) who underwent CTP within 24 hours of stroke onset and had a baseline ischemic core volume ≥70 mL was performed. The primary outcome was the estimation of the association of EVT in patients with core volume ≥70 mL and within 70-100 and ≥100 mL subgroups with fair outcome.

RESULTS

Of the 3,283 patients in the registry, 299 had CTP core volume ≥70 mL and 269 complete data (135 had core volume between 70 and 100 mL and 134 had core volume ≥100 mL). EVT was performed in 121 (45%) patients. EVT-treated patients were younger (median 69 vs 75 years; p = 0.011), had lower prestroke mRS, and smaller median core volumes (92 [79-116.5] mL vs 105.5 [85.75-138] mL, p = 0.004). EVT-treated patients had higher odds of achieving fair outcome in adjusted analysis (30% vs 13.9% in the non-EVT group; adjusted odds ratio [aOR] 2.1, 95% CI 1-4.2, p = 0.038). The benefit was seen predominantly in those with 70-100 mL core volume (71/135 [52.6%] EVT-treated), with 54.3% in the EVT-treated vs 21% in the non-EVT group achieving a fair outcome (aOR 2.5, 95% CI 1-6.2, p = 0.005). Of those with a core volume ≥100 mL, 50 of the 134 (37.3%) underwent EVT. Proportions of fair outcome were very low in both groups (8.1% vs 8.7%; p = 0.908).

DISCUSSION

We found a positive association of EVT with the 3-month outcome after stroke in patients with a baseline CTP ischemic core volume 70-100 mL but not in those with core volume ≥100 mL. Randomized data to confirm these findings are required.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that EVT is associated with better motor outcomes 3 months after CTP-defined ischemic stroke with a core volume of 70-100 mL.

Endovascular therapy in acute anterior circulation large vessel occlusive patients with a large infarct core (ANGEL-ASPECT): protocol of a multicentre randomised trial

BACKGROUND

The benefit of stroke thrombectomy for large infarct core still lacks robust randomised controlled studies.

AIM

To demonstrate the design of a clinical trial on endovascular therapy for acute anterior circulation large vessel occlusion (LVO) patients with large infarct core volume.

DESIGN

ANGEL-ASPECT is a multicentre, prospective, randomised, open-label, blinded End-point trial to evaluate whether best medical management (BMM) combined with endovascular therapy improves neurological functional outcomes as compared with BMM alone in acute LVO patients with Alberta Stroke Program Early CT Score (ASPECTS) of 3-5 on non-contrast CT or infarct core volume range of 70-100 mL (defined as rCBF <30% on CT perfusion or ADC <620 on MRI) up to 24 hours from symptom onset or last seen well.

STUDY OUTCOMES

The primary efficacy outcome is 90 (±7) days modified Rankin Scale. Symptomatic intracranial haemorrhage within 48 hours from randomisation is the primary safety outcome.

DISCUSSION

The ANGEL-ASPECT trial will screen patients with large infarct core (ASPECTS 3-5 or 70-100 mL) through image evaluation criteria within 24 hours and explore the efficacy and safety of endovascular therapy compared with BMM.

Endovascular Thrombectomy Reduces Risk of Poor Functional Outcomes in Patients Presenting within 0-6 Hours with Large Ischemic Core Volumes on Computed Tomography Perfusion

INTRODUCTION

Patients presenting with large ischemic core volumes (LICVs) on computed tomography perfusion (CTP) are at high risk for poor functional outcomes. We sought to identify predictors of outcome in patients with an internal carotid artery (ICA) or middle cerebral artery (MCA) occlusion and LICV.

METHODS

A large healthcare system's prospectively collected code stroke registry was utilized for this retrospective analysis of patients presenting within 6 hours with at least 50 ml of CTP reduced relative cerebral blood flow (CBF) < 30%. A multivariable logistic regression model was constructed to identify independent predictors (p < 0.05) of poor discharge outcome (modified Rankin scale score 4-6).

RESULTS

Over a 38-month period, we identified 104 patients meeting inclusion criteria, with a mean age of 65.4 ± 16.2 years, median presenting National Institutes of Health Stroke Scale score 20 (IQR 16-24), median ischemic core volume (CBF < 30%) 82 ml (IQR 61-118), and median mismatch volume 80 ml (IQR 56-134). Seventy-five patients (72.1%) had a discharge modified Rankin scale score of 4-6. Sixty-six of 104 (63.5%) patients were treated with endovascular thrombectomy (EVT). In the multivariable regression model, EVT (OR 0.303; 95% CI 0.080-0.985; p = 0.049) and lower blood glucose (per 1-point increase, OR 1.014; 95% CI 1.003-1.030; p = 0.030) were independently protective against poor discharge outcome.

CONCLUSIONS

EVT is independently associated with a reduced risk of poor functional outcome in patients presenting within 6 hours with ICA or MCA occlusions and LICV.

Impact of relative cerebral blood volume reduction on early neurological improvement in extensive ischemic stroke

PURPOSE

The benefit of endovascular treatment (EVT) for patients with low ASPECTS is yet ambiguous and currently investigated in randomized trials. As a tool for estimation of infarct extent and progression, CT-perfusion might predict early neurological improvement (ENI) after EVT.

OBJECTIVE

We hypothesized that the degree of relative cerebral blood volume (rCBV) reduction is directly associated with ENI in low ASPECTS patients undergoing EVT.

METHODS

Ischemic stroke patients with ASPECTS≤5 who received multimodal-CT and underwent thrombectomy were analyzed. The rCBV reduction was defined as the ratio of CBV measured in the ischemic lesion and contralateral CBV. Complete reperfusion was defined as eTICI 2c-3. Clinical endpoint was early neurological improvement (ENI) at 24-hours defined continuously (NIHSS change from baseline to 24-hours) and binarized (NIHSS at 24-hours≤8).

RESULTS

102 patients were included. Lower rCBV reduction and complete EVT were independently associated with ENI (-11.4 NIHSS points, p=0.04; -7.3 points, p<0.0001, respectively). The effect of complete EVT on ENI was directly linked to the degree of rCBV reduction: the probability for binary ENI was +34.6%, p=0.004 in patients with low rCBV reduction versus +8.2%, p=0.28 in patients with high rCBV reduction.

CONCLUSION

In ischemic stroke with low ASPECTS, ENI was directly linked to the degree of rCBV reduction as a potential indicator of ischemia depth in extensive baseline infarction. Lower rCBV reduction was associated with higher probability of ENI after complete reperfusion suggesting a less pronounced lesion progression despite its large extent and hence, a higher susceptibility to EVT.

Outcomes and CT Perfusion Thresholds of Mechanical Thrombectomy for Patients With Large Ischemic Core Lesions

Objective

To explore the clinical prognosis and factors after mechanical thrombectomy (MT) in patients with large cerebral infarction assessed by computed tomographic perfusion (CTP)and the optimal threshold of cerebral blood flow (CBF) for estimating ischemic core.

Methods

We analyzed data from the anterior circulation database of our hospital (August 2018-June 2021). Multivariate logistic regression analyses identified the predictors of clinical outcomes for patients with large baseline infarcts (>50 ml) assessed by the MIStar software. The receiver operating characteristic (ROC) analysis was used to explore the cutoff value of factors.

Results

The present study included one hundred thirty-seven patients with large baseline infarcts. Moreover, 23 (16.8%) patients achieved functionally independent outcomes, and 50 (36.5%) patients died at 90 days. A total of 20 (14.7%) patients had symptomatic intracranial hemorrhage (sICH). The multivariable analysis showed that higher age and larger core volume were independent of poor outcomes. The cutoff value of core volume was 90 ml, and the age was 76 years. Hypertension and rt-PA treatment were independent factors of sICH. Higher age and larger ischemic volume were independent risk factors of mortality.

Conclusions

Mechanical thrombectomy can be applied in patients with large ischemic core volumes. Patients older than 76 years with large cores (>90 ml) are unlikely to benefit from MT. These findings may be helpful in selecting patients with large baseline infarcts to be treated by MT. The threshold of CBF < 30% is the independent factor, and this is worth evaluating in future studies to find the optimal threshold of CBF.

Persistent challenges in endovascular treatment decision-making for acute ischaemic stroke

PURPOSE OF REVIEW

Although endovascular treatment (EVT) is the gold standard for treating acute stroke patients with large vessel occlusion (LVO), multiple challenges in decision-making for specific conditions persist. Recent evidence on a selection of patient subgroups will be discussed in this narrative review.

RECENT FINDINGS

Two randomized controlled trials (RCTs) have been published in EVT of basilar artery occlusion (BAO). Large single arm studies showed promising results in Patients with low Alberta stroke program early CT score (ASPECTS) and more distal vessel occlusions. Recent data confirm patients with low National Institutes of Health Stroke Scale (NIHSS) despite LVO to represent a heterogeneous and challenging patient group.

SUMMARY

The current evidence does not justify withholding EVT from BAO patients as none of the RCTs showed any signal of superiority of BMT alone vs. EVT. Patients with low ASPECTS, more distal vessel occlusions and patients with low NIHSS scores should be included into RCTs if possible. Without participation in a RCT, patients should be selected for EVT based on age, severity and type of neurological impairment, time since symptom onset, location of the ischaemic lesion and perhaps also results of advanced imaging.

Acute reperfusion therapies for acute ischemic stroke patients with unknown time of symptom onset or in extended time windows: an individualized approach

Recent randomized controlled clinical trials (RCTs) have revolutionized acute ischemic stroke care by extending the use of intravenous thrombolysis and endovascular reperfusion therapies in time windows that have been originally considered futile or even unsafe. Both systemic and endovascular reperfusion therapies have been shown to improve outcome in patients with wake-up strokes or symptom onset beyond 4.5 h for intravenous thrombolysis and beyond 6 h for endovascular treatment; however, they require advanced neuroimaging to select stroke patients safely. Experts have proposed simpler imaging algorithms but high-quality data on safety and efficacy are currently missing. RCTs used diverse imaging and clinical inclusion criteria for patient selection during the dawn of this novel stroke treatment paradigm. After taking into consideration the dismal prognosis of nonrecanalized ischemic stroke patients and the substantial clinical benefit of reperfusion therapies in selected late presenters, we propose rescue reperfusion therapies for acute ischemic stroke patients not fulfilling all clinical and imaging inclusion criteria as an option in a subgroup of patients with clinical and radiological profiles suggesting low risk for complications, notably hemorrhagic transformation as well as local or remote parenchymal hemorrhage. Incorporating new data to treatment algorithms may seem perplexing to stroke physicians, since treatment and imaging capabilities of each stroke center may dictate diverse treatment pathways. This narrative review will summarize current data that will assist clinicians in the selection of those late presenters that will most likely benefit from acute reperfusion therapies. Different treatment algorithms are provided according to available neuroimaging and endovascular treatment capabilities.