First-line contact aspiration versus first-line stent retriever for acute ischemic stroke with M2 occlusion: A systematic review and meta-analysis

Objective: Mechanical thrombectomy is widely used for acute ischemic stroke caused by middle cerebral artery M2 segment occlusion. However, the comparison between contact aspiration (CA) and stent retriever (SR) used as first-line techniques for acute M2 occlusion is still unclear. We aimed to perform a systematic review and metaanalysis on this issue. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement was followed. Three databases (Pubmed, Embase, and Cochrane) were searched. The Newcastle-Ottawa scale was used to assess the risk of bias for the included studies. We focused on two main outcomes, the final successful reperfusion (modified Thrombolysis in Cerebral Infarction mTICI 2b/3) and 90-day functional independence (modified Rankin Scale score 0-2). The meta-analyses were performed using the random-effects models. Results: Seven observational studies were included for systematic review. Only one study indicated a superiority of first-line SR in achieving final successful reperfusion, while the other six studies did not show significant difference between these two techniques. And all the seven studies showed comparable proportion of 90-day functional independence. Five studies were available for meta-analysis with 601 patients (239 received firstline CA, 362 received first-line SR). The pooled results also suggested that the proportion of final successful reperfusion (OR=1.18, 95%CI 0.72-1.93, I2 =0%) and 90-day functional independence (OR=1.18, 95%CI 0.82-1.68, I2 =0%) were comparable between these two strategies. Conclusion: For patients with acute M2 occlusion, first-line CA and SR techniques could achieve similar final reperfusion outcomes and 90-day clinical prognosis. Further studies with randomized controlled design are needed.