Intravenous Thrombolysis Use in the Late Time Window Before Interhospital Transfer for Thrombectomy

Importance In patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO), the benefit of intravenous thrombolysis (IVT) administered beyond 4.5 hours from the last time known well before endovascular therapy (EVT) is uncertain. Recently, the TIMELESS trial failed to demonstrate a benefit of IVT in this setting, but this trial focused on patients directly admitted to comprehensive stroke centers (CSCs) with fast access to EVT. Objective To assess the efficacy and safety of IVT initiated beyond 4.5 hours in patients with AIS-LVO initially admitted to primary stroke centers (PSCs) and subsequently transferred to a CSC for EVT, allowing substantial time for the IVT to take effect. Design, Setting, and Participants This multicenter retrospective cohort study was conducted between January 2020 and December 2024, with 3-month follow-up, at 20 French PSCs. All consecutive patients with AIS-LVO admitted beyond 4.5 hours from the last time they were known well in the PSC and subsequently transferred to a CSC for EVT, with or without IVT administered prior to transfer, were eligible for inclusion. Data analysis was performed between May 2025 and July 2025. Main Outcomes and Measures The primary outcome was the 3-month modified Rankin Scale score, analyzed in the ordinal approach. Propensity score with overlap weighting (PSOW) balanced covariates between patients treated with IVT vs those without. Results A total of 584 patients were included, among whom 309 patients (52.9%) were female. Median (IQR) age was 71 (61-81) years, median (IQR) baseline National Institutes of Health Stroke scale score was 15 (10-19), median (IQR) time from last known well to PSC imaging was 10.5 (6.9-14.0) hours, and 232 patients (39.7%) received IVT before transfer. Advanced brain imaging (magnetic resonance imaging or computed tomography [CT] with CT-perfusion) was performed at the PSC in 544 patients (93.2%). IVT use before transfer was independently associated with a shift toward better 3-month outcomes (PSOW–common odds ratio [OR], 1.97; 95% CI, 1.33-2.92; P = .001) and higher odds of recanalization during transfer (PSOW-OR, 8.69; 95% CI, 3.16-23.87; P < .001) compared with those without. The rate of any intracerebral hemorrhage and symptomatic intracerebral hemorrhage were similar between groups. Conclusions and Relevance In this multicenter cohort study, IVT initiated beyond 4.5 hours prior to interhospital transfer for EVT was associated with higher rates of recanalization during transfer and improved 3-month functional outcomes, without safety concerns. These findings offer encouraging support for clinical trials evaluating IVT in the late time window before interhospital transfer.