Efficacy of intravenous thrombolysis beyond 4.5 to 24 hours in patients with isolated posterior circulation acute ischemic stroke

ObjectiveTo compare the functional outcomes and safety of intravenous thrombolysis (IVT) administered within the standard 4.5-hour time window versus an extended time window of >4.5-24 h after symptom onset in patients with isolated posterior circulation acute ischemic stroke (AIS).MethodsData from patients with isolated posterior circulation AIS who received IVT between January 2017 and December 2024 were extracted from the Acute Stroke Patients for Stroke Management Quality Evaluation online database (CASE-Ⅱ, NCT04487340). Patients were categorized into the standard time window group (within 4.5-hour) and the extended time window group (>4.5-24 h). The primary outcome was 3-month functional independence (modified Rankin Scale score 0-2). Multivariate logistic regression and propensity score matching were used to compare outcomes. Interaction tests assessed the consistency of the time window effect across subgroups predefined by age, sex, baseline National Institutes of Health Stroke Scale (NIHSS) score, presence of large vessel occlusion, thrombolytic agent, and trial of ORG 10172 in acute stroke treatment (TOAST) subtype.ResultsAmong 3508 included patients, 3147 were in the standard time window group and 361 in the extended time window group. The rate of 3-month functional independence did not significantly differ between the two groups (80.1% vs. 78.7%, adjusted OR=0.896, 95%CI: 0.655-1.226, P>0.05). This finding remained consistent after propensity score matching (adjusted OR=1.122, 95%CI: 0.724-1.738, P>0.05). In the entire cohort, each 30-minute delay in ONT was associated with a 2.6% decrease in the probability of functional independence (OR=0.974, 95%CI: 0.952-0.996, P=0.02). This negative association was significant only within the standard time window group (OR=0.934, 95%CI: 0.887-0.984, P=0.01). Subgroup analysis indicated that the standard time window group had a higher rate of functional independence than the extended time window group (both interactions P5 or those with large vessel occlusion. No significant differences were observed in safety outcomes, including 24 h symptomatic intracranial hemorrhage, early neurological deterioration, and 3-month all-cause mortality.ConclusionFor patients with isolated posterior circulation AIS, IVT administered within >4.5-24 h after onset demonstrates effectiveness and safety comparable to treatment within the standard 4.5-hour time window.