Abstract 467: Early (≤6h) Vs. Late (>6h ‐ 24h) Window Thrombectomy for Acute Ischemic Stroke: A Pooled Analysis of 39,732 patients

Background The clinical benefit of mechanical thrombectomy (MT) for acute ischemic stroke (AIS) caused by large vessel occlusion has been well established through recent clinical trials. While the recommended time window is within six hours from symptoms onset, pushing the edges towards the extension beyond six hours carries the potential to increase the number of eligible patients. Comparing the outcomes of late window MT with those of early window intervention remains a matter of clinical importance. Methods A systematic literature review and meta‐analysis was conducted, including studies comparing late (>6h ‐ 24h) versus early (≤ 6h) MT for AIS patients from inception till June 2025. Outcomes analyzed were functional independence (modified Rankin Scale mRS 0‐2), excellent functional recovery (mRS 0‐1), 90‐day mortality, and symptomatic ICH (sICH). Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using fixed‐ or random‐effects models according to heterogeneity. Results Sixteen studies, with a total of 39,732 patients (early window= 30,413, late window=9,319), were included in our analysis. Compared to early window MT, the late window was significantly associated with lower odds of achieving functional independence (OR, 0.83; 95%CI 0.79, 0.87; P=0.00; I2= 54.5%), and excellent functional recovery (OR, 0.81; 95%CI 0.74, 0.87; P=0.00; I2= 0%). However, we found no significant differences between either groups in sICH (OR, 1.01; 95%CI 0.91, 1.12; P=0.89; I2= 22.9%), and 90‐day mortality (OR, 0.99; 95%CI 0.92, 1.06; P=0.76; I2= 47.1%). Conclusions Although patients treated with MT in the late window (6‐24h) achieve less favorable functional outcomes compared with early intervention, late thrombectomy does not increase mortality or hemorrhagic complications, underscoring its safety in carefully selected patients. These findings highlight that while earlier treatment maximizes recovery potential, future research on late window thrombectomy remains highly warranted. image