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.