Beyond the Golden Hours: M2 Thrombectomy Outcomes Within and Beyond 6 Hours

Introduction: Mechanical thrombectomy (MT) is an established treatment for large vessel occlusions in acute ischemic stroke (AIS), but It’s role in medium vessel occlusions (MeVOs), particularly M2 segment occlusions, remains less defined. This study aimed to evaluate the safety and efficacy of MT for M2 occlusions in two time windows: early (<6 hours) and late (6–24 hours).Material and Methods: In this single-center cohort study, 23 patients with confirmed M2 occlusions underwent MT from October 2021 to October 2024 and were categorized into two groups: early (<6 hours, n = 12) and late (6–24 hours, n = 11). Advanced imaging was used for late-window selection. Baseline characteristics, procedural data, and outcomes, reperfusion success (modified TICI 2b/3), neurological improvement (NIHSS), functional recovery (mRS ≤2), and complications were analyzed.Results: The successful reperfusion rates were similar between the early and late groups (75% vs. 73%, P = 0.373). Both groups demonstrated significant neurological improvement (NIHSS change: early 6 ± 3, late 7 ± 3; P = 0.926) and favorable 3-month outcomes (mRS ≤ 2: early 66.7%, late 72.7%; P = 0.831). Procedural times were longer in the late group (52.91 vs. 42.50 minutes, P = 0.088), though not statistically significant. Complication rates were low and comparable.Conclusion: MT for M2 occlusions appears safe and effective in both early and late windows when guided by advanced imaging. Larger studies are warranted to confirm these findings. Keywords: Mechanical thrombectomy; rTPA; M2 segment; catheter retrieval.