Endovascular thrombectomy in late-window stroke: Do perfusion imaging and large infarcts really matter? A systematic review and meta-analysis of 10 randomized clinical trials.

Background: Several randomized trials have evaluated the benefits of endovascular thrombectomy (EVT) for anterior circulation large vessel occlusion strokes presenting beyond 6 hours of the last known well (LKW). We aimed to synthesize the results from these trials to provide high-level evidence regarding EVT treatment for patients presenting in the late window.

Methods: A systematic search was conducted through four electronic databases, with no language restriction. Binary outcomes were analyzed using the risk ratio (RR) and 95 % confidence interval (CI), while continuous outcomes were analyzed using the standardized mean difference (SMD) and 95 % CI.

Results: Out of 2824 patients from 10 trials comparing EVT plus BMT and BMT alone among patients with AIS who presented beyond 6 hours of LKW, 1871 patients (n = 981 EVT, n = 890 BMT) were included in the analysis. The results showed benefits toward the EVT than BMT alone in Modified Rankin Scale (mRS) 0-1 (RR= 1.84, 95 %CI= 1.4- 2.4), mRS 0-2 (RR= 2.3, 95 %CI= 1.5- 2.1), and mRS 0-3 (RR= 1.64, 95 %CI= 1.3- 1.63) at three months. No significant difference between EVT and BMT alone groups was found when analyzing either 90-day mortality or symptomatic intracranial hemorrhage. Subgroup analysis showed that there was no significant difference between patients with large core stroke and patients with non-large core stroke in 90-day mRS 0-2 (RR= 3.6 vs 2.37, P-value=0.26). Findings did not show significant difference between perfusion vs non-perfusion imaging modalities in 90-day mRS 0-2 and mortality.

Conclusion: These findings strengthen the previous evidence for the benefits of EVT over medical treatment in managing patients with stroke, even with large ischemic regions in the late time window.