Stroke thrombectomy for large infarcts with limited penumbra: Systematic review and meta-analysis of randomized trials.

Background and purpose: 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 largely unknown.

Materials and methods: This was a meta-analysis of randomized controlled trials reporting the effectiveness of EVT for large infarcts stratified by perfusion mismatch profiles. Patients with mismatch ratio 1.2-1.8 or penumbra volume 10-15cc (intermediate mismatch) or mismatch ratio <1.2 or volume <10cc (low mismatch) were included. Odds of 90-day modified Rankin scale (mRS) 0 to 3 (good) and 5 to 6 (poor) were calculated and effect sizes were pooled using Mantel-Haenszel fixed-effects models.

Results: Two trials - SELECT2 and ANGEL-ASPECT - were included; 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 to 3 for intermediate mismatch (pooled OR 2.77 [95%CI 1.11-6.89], p=0.028; Figure 1), but not low mismatch (pooled OR 1.47 [95%CI 0.444.94], p=0.54; Figure 1). Similarly, in terms of 90-day poor outcomes (mRS 5 or 6), EVT for intermediate mismatch patients was significantly associated with lower odds (OR 0.49 [95%CI 0.24 to 0.99], p=0.046; Figure 2), while EVT for the low mismatch cohort was not (OR 0.66 [95%CI 0.22 to 1.96], p=0.45; Figure 2). There was no significant inter-study heterogeneity observed across study estimates.

Conclusions: For patients with large infarcts, EVT appears to be likely 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. These data generally support the continued use of perfusion imaging to select patients with large infarcts for EVT if it is available at the treating institution. Future studies and trials should consider investigating the efficacy and safety of EVT for patients with large infarcts and low mismatch profiles.

Abbreviations: EVT = endovascular thrombectomy; MM = medical management; OR = odds ratio; CI = confidence interval.