Stent retriever versus direct aspiration thrombectomy for acute large vessel occlusion: A meta-analysis including 17,556 patients, from MR CLEAN to present

Objective: Stent retriever (SR) and direct aspiration (DA) mechanical thrombectomy (MT) improve clinical outcomes for stroke secondary to large vessel occlusion. The purpose is to perform an updated meta-analysis comparing the two techniques.Methods: PubMed database was searched for studies between January 1, 2015, and July 5th, 2021 with mechanical thrombectomy to treat acute ischemic stroke.Results: We identified 136 studies including 17,556 patients, with 11,258 (64.1%) patients treated by SR or a combined approach and 6298 (35.9%) patients with DA. The DA group had less posterior cerebral artery strokes, was significantly older, and had lower National Institutes of Health Stroke Scale scores (p = .05,.02,.04) There was no difference between groups in percentage of middle cerebral artery or internal carotid artery occlusions or intravenous tissue plasminogen activator administered (p = .62,.19,.06). A regression model showed no difference between SR and DA in mortality, symptomatic intracranial hemorrhage, and disability (mRS > 2) at 90 days (p = .13,.75,.84). Successful reperfusion (mTICI 2b/3 rates) were higher in the DA group (DA 87.6% vs SR 82.3%, p < .01), but after accounting for covariates was not significant (p = .17). Conclusion: Our updated meta-analysis shows that DA has similar safety, reperfusion and 90-day clinical outcomes compared to SR. These results should serve to increase confidence in DA thrombectomy for acute ischemic stroke secondary to LVO.