Direct aspiration vs. stent retriever for middle cerebral artery M2 occlusion: a systematic review and meta-analysis.

Thrombectomy with direct aspiration (DA) or stent retriever (SR) are equally effective for endovascular treatment of proximal occlusions. However, their efficacy and safety in distal occlusions, such as those in the M2 segment of the middle cerebral artery, remain uncertain. Therefore, we aim to compare the efficacy and safety of these two approaches in M2 occlusions. This systematic review was registered in PROSPERO (CRD42025649001). We searched PubMed, EMBASE, Web of Science, and Cochrane Library for studies comparing DA to SR in patients with middle artery M2 occlusion until June 2025. The primary endpoint was successful reperfusion (modified Thrombolysis in Cerebral Infarction score [mTICI] 2b-3), and secondary endpoints included complete reperfusion (mTICI 3), first-pass successful reperfusion, favorable functional outcome (modified Rankin Scale [mRS] ≤ 2), symptomatic intracranial hemorrhage (sICH), subarachnoid hemorrhage (SAH), vasospasm, and mortality. Statistical analysis was conducted in R Studio (version 2024.12.1 + 563), using risk ratio (RR) with 95% confidence intervals (CI). Twelve studies were included (N, 1578; age, 69.8 ± 9 years; men, 52.0%). DA was associated with higher likelihood of successful reperfusion (RR 1.06 [95% CI: 1.01–1.11], P = .02; I2 = 0%). Meta-regression analysis showed that between-studies variability in age, NIHSS, ASPECTS, use of intravenous thrombolysis, history of stroke, atrial fibrillation, hypertension, diabetes mellitus, history of smoking, and dyslipidemia did not significantly alter the pooled estimate of successful reperfusion. Furthermore, DA was associated with a lower risk of SAH (RR 0.29 [95% CI: 0.10–0.81], P = .03; I2 = 0%). However, complete reperfusion, first-pass successful reperfusion, favorable functional outcome, sICH, vasospasm, and mortality did not significantly differ between groups. In this meta-analysis, DA for middle artery M2 occlusion led to a higher likelihood of successful reperfusion and a lower risk of SAH when compared to SR.