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

Stroke Thrombectomy for Large Infarcts with Limited Penumbra: Systematic Review and Meta-Analysis of Randomized Trials

BACKGROUND

Recent randomized trials have suggested that endovascular thrombectomy (EVT) is superior to medical management (MM) for stroke patients with large infarcts. However, whether or how perfusion metrics should be used to guide optimal patient selection for treatment is unknown.

PURPOSE

To synthesize trial results to provide more definitive guidance on the role of EVT for stroke patients with large infarcts based on perfusion metrics.

DATA SOURCES

MEDLINE database from inception up to July 8, 2024. Randomized controlled trials that report the efficacy and safety of EVT for patients with large infarcts (defined by either infarct core volume greater than 50cc or Alberta Stroke Program Early CT Score [ASPECTS] less than 6) stratified by mismatch profile were included.

STUDY SELECTION

Five trials were identified - SELECT2 and ANGEL-ASPECT.

DATA ANALYSIS

The primary outcome was odds of acceptable outcomes (90-day modified Rankin scale [mRS] 0 to 3). Secondary outcome was 90-day mRS 5 or 6. Patients where then subdivided into those with mismatch ratio 1.2-1.8 or penumbra volume 10-15cc (intermediate mismatch) and those with mismatch ratio <1.2 or volume <10cc (low mismatch).

DATA SYNTHESIS

A total of 140 intermediate mismatch (75 EVT and 65 MM) and 60 low mismatch patients (23 EVT and 37 MM) were identified. EVT was significantly associated with higher odds of mRS 0-3 for intermediate mismatch (OR 2.77 [95% CI 1.11-6.89], P = .028), but not low mismatch (OR 1.47 [95% CI 0.44-4.94], P = .54). Similarly, in terms of 90-day poor outcomes (mRS 5-6), EVT for intermediate mismatch patients was significantly associated with lower odds (OR 0.49 [95% CI 0.24 to 0.99], P = .046), while EVT for the low mismatch cohort was not (OR 0.66 [95% CI 0.22 to 1.96], P = .45). There was no significant inter-study heterogeneity observed across study estimates.

CONCLUSIONS

For stroke patients with large infarcts, EVT was beneficial for patients with perfusion mismatch ratio and volume of at least 1.2 and 10cc, but not for those with mismatch ratio <1.2 or volume <10cc.

Endovascular thrombectomy in acute stroke with a large ischemic core: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Endovascular thrombectomy (EVT) is the standard treatment for acute ischemic stroke due to internal carotid artery (ICA) or middle cerebral artery (MCA) M1 occlusion with a small ischemic core. However, the effect of EVT on acute stroke with a large ischemic core remains unclear. This study aimed to evaluate the association of EVT plus medical care versus medical care alone with outcomes in patients with acute stroke and a large ischemic core due to ICA or MCA M1 occlusion.

METHODS AND FINDINGS

PubMed, the Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov were searched from January 1, 2000 to September 25, 2024. There were no language restrictions. Randomized controlled trials (RCTs) of patients with acute stroke and a large ischemic core that compared EVT plus medical care versus medical care alone were evaluated. We computed the random-effects estimate based on the inverse variance method. Risk ratio (RR) with 95% confidence interval (CI) was used to measure outcomes of EVT plus medical care versus medical care alone. The primary outcome was functional independence, defined as modified Rankin Scale (mRS) of 0-2 at 90 days post-stroke; and the lead secondary outcome was reduced disability, defined as ordinal shift of mRS. Safety outcomes were requiring constant care or death (mRS 5-6), death, and early symptomatic intracranial hemorrhage (sICH). Grading of Recommendations Assessment, Development and Evaluations (GRADE) was used to evaluate summaries of evidence for the outcomes. We included six RCTs comprising 1870 patients (826 females [44.2%]) with acute stroke and a larger moderate or large ischemic core due to ICA or MCA M1 occlusion. All patients were nondisabled before stroke. Pooled results showed that at 90 days post-stroke, EVT plus medical care, compared with medical care alone, was associated with greater functional independence (RR 2.53, 95% CI [1.95, 3.29]; p  < 0.001; number needed to treat [NNT], 9, 95% CI [6,15]) and reduced disability (common odds ratio 1.63, 95% CI [1.38, 1.93]; p < 0.001; NNT, 4 [minimum possible NNT, 2; maximum possible NNT, 6]). EVT plus medical care, compared with medical care alone, was associated with a lower risk of requiring constant care or death (RR 0.74, 95% CI [0.66, 0.84]; p  <  0.001; NNT, 7, 95% CI [6,11]). EVT plus medical care, compared with medical care alone, was associated with a nonsignificantly higher proportion of patients with early symptomatic intracranial hemorrhage (RR 1.65, 95% CI [1.00, 2.70]; p  =  0.05). The rates of death were not significantly different between the EVT plus medical care and medical care alone groups (RR 0.86, 95% CI [0.72, 1.02]; p  =  0.08). Main limitations include variability in imaging definitions of large core and inclusion of both larger moderate and large cores in the analysis.

CONCLUSIONS

Among patients with acute stroke and a larger moderate or large ischemic core due to ICA or MCA M1 occlusion who were nondisabled before stroke, EVT plus medical care, compared with medical care alone, may be associated with improved functional independence, reduced disability, and reduced rates of severe disability or death at 90 days post-stroke. PROSPERO registration number: CRD42024514605.

The apparent diffusion coefficient color Map for evaluating a large ischemic core

INTRODUCTION

Our previous work demonstrated that evaluating large ischemic cores using the apparent diffusion coefficient (ADC) could predict EVT outcomes, with the most frequent ADC (peak ADC) ≥520×10-6 mm2/s associated with better clinical results. Since the degree of ADC reduction reflects the severity of ischemic stress, this study aimed to assess the utility of an ADC color map in visualizing this stress.

PATIENTS AND METHODS

This retrospective cohort study included consecutive patients with a low Alberta Stroke Program Early Computed Tomography Score (ASPECTS) using diffusion-weighted imaging (DWI) who underwent successful EVT recanalization between April 2014 and March 2023. To create a visual representation of ischemic stress, we assigned different colors to diffusion-weighted image (DWI) lesions based on their ADC values: ≥520×10-6 mm2/s, 520-440×10-6 mm2/s, and <440×10-6 mm2/s. We compared patients with peak ADC ≥520×10-6 mm2/s to those with lower peak ADC to identify factors associated with the higher value.

RESULTS

A total of 78 patients were enrolled, with 34 having a peak ADC ≥520×10-6 mm2/s. The optimal ratio for discriminating peak ADC ≥520×10-6 mm2/s was found to be 60 % for the volume of the lesion with ADC ≥520×10-6 mm2/s (ADC520) relative to the total DWI lesion volume. This ratio demonstrated a sensitivity of 86 % and a specificity of 82 %.

DISCUSSION AND CONCLUSION

The ADC color map effectively portrays the depth of ischemic stress. A large ischemic core with an ADC520/DWI ratio >60 % may be salvageable with EVT. This approach offers a visual means for assessing EVT suitability in acute large ischemic stroke.

Mismatch Vs No Mismatch in Large Core-A Matter of Definition

BACKGROUND

Endovascular thrombectomy (EVT) has shown promise in randomized controlled trials (RCTs) for large ischemic core stroke patients, yet variability in core definition and onset-to-imaging time creates heterogeneity in outcomes. This study aims to clarify the prevalence and implications of core-perfusion mismatch (MM) versus no mismatch (No MM) in such patients, utilizing established imaging criteria.

METHODS

A retrospective cohort study was conducted including patients from 7/29/2019 to 1/29/2023, with data extracted from a continuously maintained database. Patients were eligible if they met criteria including multimodal CT imaging performed within 24 h from last known well (LKW), AIS-LVO diagnosis, and ischemic core size defined by specific rCBF thresholds. Mismatch was assessed based on different operational definitions from the EXTEND and DEFUSE 3 trials.

RESULTS

Fifty-two patients were included, with various time windows from LKW. Using EXTEND criteria, a significant portion of early window patients exhibited MM; however, fewer patients met MM criteria in the late window. Defining MM using DEFUSE 3 criteria yielded similar patterns, but with overall lower MM prevalence in the late window. When employing rCBF <38% as a surrogate for ischemic core, a higher percentage of patients were classified as MM across both time windows compared to rCBF <30%.

CONCLUSION

The prevalence of MM in large ischemic core patients varies significantly depending on the imaging criteria and time from LKW. Notably, MM was more prevalent in the early time window across all criteria used. Additional RCTs are needed to determine if this definition of MM identifies patients who will benefit most from EVT.

Beyond conventional imaging: A systematic review and meta-analysis assessing the impact of computed tomography perfusion on ischemic stroke outcomes in the late window

BACKGROUND

Non-contrast cranial computed tomography (NCCT) and CT angiogram (CTA) have become essential for endovascular treatment (EVT) in acute stroke. Patient selection may improve when CT perfusion (CTP) imaging is also added for patient selection. We aimed to analyze the effects of implementing CTP in acute ischemic stroke (AIS) patients' treatment to assess whether stroke outcomes differ in the late window.

METHODS

We searched the PubMed, Embase, and Web of Sciences databases to obtain articles related to CTA and CTP in EVT. Collected patient data were split into two groups: the CTP and control (NCCT + CTA) cohorts. Primary outcomes evaluated were modified Rankin Scale (mRS) scores, symptomatic intracranial hemorrhages (sICHs), mortality, and successful recanalization.

RESULTS

There were 14 studies with 5809 total patients in the final analysis: 2602 received CTP and 3202 were in the control group. CTP/CTA patients showed significantly lower rates of 90-day stroke-related mortality (odds ratio (OR) = 0.72, 95% confidence interval (CI) = 0.60-0.87, p < 0.01) and significantly higher successful recanalization (OR = 1.42, 95% CI = 1.06-1.94, p < 0.01) compared with CTA-only patients. Analysis of other outcomes including functional independence (mRS = 0-2), critical times, and intracranial hemorrhages was non-significant (p > 0.05).

CONCLUSION

The study highlights the usefulness of CTP-guided therapy as a supplementary tool in EVT selection in the late window. Although the addition of CTP resulted in lower mortality, the favorable outcomes did not improve. Further evidence is required to establish a clearer understanding of the potential advantages or limitations of incorporating CTP in stroke imaging.

Current gaps in acute reperfusion therapies

PURPOSE OF REVIEW

Advances in intravenous thrombolysis and endovascular thrombectomy have significantly reduced disability and improved outcomes associated with acute ischemic stroke.

RECENT FINDINGS

An expansion of indications for reperfusion therapies in select groups of patients to permit treatment in an extended time window, with large ischemic core, and with simplified imaging protocols have enabled a broader group of patients access to disability-sparing therapy. Cerebroprotection has had renewed development in the era of acute reperfusion.

SUMMARY

In this review, we highlight recent developments in stroke reperfusion research and related questions that are under study or remain unanswered.