Abstract DP292: Endovascular Thrombectomy Enhances Functional Outcomes and Reduces Cerebral Edema in Large Core Stroke Within 24 Hours: An Observational Cohort Study

Introduction: Endovascular Thrombectomy (EVT) has demonstrated efficacy and safety in patients with large infarct cores (LIC). However, mortality and severe disability remain high, particularly among patients with cerebral edema. We aimed to assess EVT's efficacy on functional outcomes and cerebral edema in patients with unrestricted large core strokes within 24 hours using non-contrast CT (NCCT). Methods: We conducted a prospective observational cohort study in Vietnam, from October 2023 to May 2025, enrolling patients with large-vessel occlusion in the anterior circulation, National Institutes of Health Stroke Scale (NIHSS) score ≥ 6, Alberta Stroke Program Early CT Score (ASPECTS) < 6 at baseline, and admission within 24 hours of onset. An ambulatory outcome was defined as a modified Rankin Scale of 0-3 at 90 days. Safety outcomes were determined by death at 90 days, symptomatic intracranial hemorrhage (sICH) according to SITS-MOST criteria, and cerebral edema was defined as mass effect with a maximum midline shift ≥ 5 mm on follow-up MRI or NCCT performed at 24 hours. We used inverse probability of treatment weighting (IPTW) combined with multivariable adjustment for potential confounders, including age, sex, baseline ASPECTS, NIHSS score, and time from onset to admission. Results: We analyzed 185 patients (EVT group: 106; medical-care group: 79). Median age was 67 years (IQR 60-77), 47% were females. At admission, the median NIHSS was 18 (IQR 15-21), and ASPECTS was 3 (IQR 2-4). In the IPTW-adjusted data set, EVT was associated with a higher rate of ambulatory outcome versus medical care (48.1% vs 20.3%; IPTW-adjusted odds ratio (IPTW-aOR) 2.30, 95% CI 1.41–3.74; p<0.001) and lower 90-day mortality (30.2% vs 50.6%; IPTW-aOR 0.50, 95% CI 0.31–0.80; p=0.004). The sICH rate was numerically higher with EVT (11.3% vs 10.1%; IPTW-aOR 1.64, 95% CI 0.87–3.09; p=0.125) but not significant. Cerebral edema with mass effect was less frequent after EVT (33% vs 50.6%; IPTW-aOR 0.51, 95% CI 0.31–0.83, p=0.006) and was independently associated with poor outcome at 90 days (IPTW-aOR 3.75, 95% CI 2.04–6.89, p<0.001). Conclusion: This study shows EVT improved functional outcomes and survival while reducing cerebral edema compared with medical care. Cerebral edema with mass effect was an independent predictor of poor outcome, suggesting that part of EVT’s benefit may be mediated through the mitigation of cerebral edema. Further studies are needed to confirm these findings.