ABSTRACT NUMBER: ESOC2026A610 BEYOND THE 90-DAY BENCHMARK: A MULTICENTER LONGITUDINAL ANALYSIS OF ONE-YEAR FUNCTIONAL STATE TRANSITIONS AFTER THROMBECTOMY FOR LARGE-CORE STROKE

Abstract Background and aims Although endovascular thrombectomy improves outcomes in large-core stroke, the adequacy of 90-day endpoint to capture functional recovery remains uncertain. Methods This prospective, multicenter study enrolled consecutive patients with large-core stroke (ASPECTS ≤5) treated with EVT at four comprehensive stroke centers between 07/2023 and 09/2025. Functional status was assessed using the modified Rankin Scale (mRS) at discharge and at 30-90-180-365-day by independent, blinded, mRS-certified neurologists at each interval. Functional outcomes were grouped as independent (mRS 0–2), moderate disability (mRS 3–4), or severe disability/death (mRS 5–6). Secondary outcomes included symptomatic intracranial hemorrhage (sICH, SITS-MOST) and 90-day mortality. Longitudinal functional states were analyzed using cumulative link mixed models (CLMM) with random intercepts, adjusting for categorical time, center clustering, age, NIHSS, ASPECTS, onset-to-puncture, and reperfusion success. NCT06016348. Results Of 410 patients, 372 (90.7%) completed 1-year follow-up (median age 64, NIHSS 18, ASPECTS 4; successful reperfusion 89.8%). sICH occurred in 10.2%, and 90-day mortality was 16.5%. Functional independence increased from 9.7% (discharge) to 29.0% (90 days) and 39.8% (365 days), while severe disability or death declined from 51.6% to 31.2%. In adjusted CLMM, the greatest significant shift occurred between 90 and 180 days (OR 2.85, 95% CI 1.95–4.18; p<0.001), stabilizing thereafter (OR 1.14, 95% CI 0.78–1.67; p=0.495), highlighting moderate disability as a pivotal transitional state. Conclusions In large-core stroke, meaningful recovery after EVT continues well beyond 90 days, peaking between 90 and 180 days. Ninety-day endpoints may systematically underestimate EVT benefit, with implications for future trial design. Conflict of interest Trung Quoc Nguyen: nothing to disclose, Khang Vinh Nguyen: nothing to disclose, Thien Quang Le: nothing to disclose, Lanh Chi Nguyen: nothing to disclose, Dung Tri Bach: nothing to disclose, Hang Minh Thi Tran: nothing to disclose, Dinh Bao Chau Hoang: nothing to disclose, Thang Ba Nguyen: nothing to disclose, Thang Huy Nguyen: nothing to disclose. Figure 1 - belongs to Results Figure 2 - belongs to Conclusions