Late-Window IV Thrombolysis Before Transfer May Improve Stroke Outcomes
Key Clinical Summary
- Intravenous thrombolysis (IVT) administered before transfer from primary stroke centers was linked to better 3-month functional outcomes in large vessel occlusion stroke.
- Patients receiving late-window IVT showed higher recanalization rates during transfer compared with no IVT.
- Rates of intracerebral hemorrhage were similar, suggesting no increased safety risk.
A multicenter French cohort study published in JAMA Neurology evaluated whether intravenous thrombolysis (IVT) given beyond the conventional 4.5-hour window—before interhospital transfer for endovascular thrombectomy (EVT)—improves outcomes in acute ischemic stroke due to large vessel occlusion (AIS-LVO). Findings suggest potential functional benefits and higher recanalization rates without added hemorrhagic risk.
Study Findings
The retrospective cohort included 584 patients treated at 20 French primary stroke centers from January 2020 to December 2024. Median age was 71 years (IQR 61–81) with a baseline NIH Stroke Scale score of 15 (IQR 10–19). Median time from last known well to initial imaging was 10.5 hours (IQR 6.9–14.0). Advanced imaging (MRI or CT perfusion) was obtained in 93.2% of cases.
Of the cohort, 232 patients (39.7%) received IVT prior to transfer for EVT. Using propensity score overlap weighting to adjust for baseline differences, late-window IVT was significantly associated with improved 3-month modified Rankin Scale outcomes (common OR 1.97; 95% CI, 1.33–2.92; P = .001) compared with those who did not receive IVT. Recanalization during transfer was also more common in the IVT group (PSOW-OR 8.69; 95% CI, 3.16–23.87; P < .001).
Importantly, rates of any intracerebral hemorrhage and symptomatic intracerebral hemorrhage did not differ between groups, suggesting an acceptable safety profile in this late-window cohort. These results support the hypothesis that prolonged exposure to IVT prior to EVT may be clinically beneficial.
Clinical Implications
For clinicians managing AIS-LVO patients at centers without immediate EVT capability, these findings highlight a potential role for late-window IV thrombolysis prior to transfer. Traditional guidelines recommend IVT within 4.5 hours of last known well; however, this study suggests that when transfer times are prolonged, administration of IVT beyond this window could improve functional outcomes at 3 months and increase recanalization success during transfer.
This evidence may be particularly relevant in regions with limited access to comprehensive stroke centers, where delays in EVT are common. It underscores the importance of rapid imaging, careful patient selection based on perfusion imaging criteria, and streamlined protocols for initiating IVT even when beyond standard time thresholds. While encouraging, these observational results should be confirmed in prospective randomized trials before changes to guidelines.
Conclusion
Late-window intravenous thrombolysis before interhospital transfer for thrombectomy in AIS-LVO patients was associated with improved outcomes and higher recanalization without increased safety concerns. Prospective trials are needed to confirm benefit and inform guideline updates.
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