Abstract Number: Esoc2026a2251 Stretching the Clock: Reassessing Intravenous Thrombolysis Beyond 4.5 Hours in Acute Ischemic Stroke—a Meta-Analysis of Over 50,000 Patients

Abstract Background and aims Intravenous thrombolysis (IVT) is a well-established treatment for acute ischemic stroke (AIS) when administered within 4.5 hours of symptom onset. However, a substantial number of patients arrive at medical facilities outside this window, restricting their access to this therapy. Recent studies indicate that with the help of advanced imaging techniques, IVT might still be beneficial beyond the standard timeframe. This systematic review and meta-analysis evaluate the effectiveness and safety of administering IVT after the 4.5-hour mark in AIS patients. Methods A comprehensive literature search was carried out across PubMed, Scopus, and Web of Science to identify studies comparing IVT beyond 4.5 hours to either standard non-thrombolytic treatment or to IVT within the traditional window. Results Eighteen studies met inclusion criteria. Patients receiving IVT beyond 4.5 hours showed significantly better chances of favorable neurological outcomes (modified Rankin Scale mRS 0–1 at 90 days) compared to those who did not receive IVT (RR: 1.21; 95% CI: 1.08–1.36, p=0.001). There was no significant difference in overall mortality (p=0.3). However, the incidence of symptomatic intracranial hemorrhage (sICH) was higher in patients treated beyond 4.5 hours (RR: 2.23; 95% CI: 1.19–4.18, p=0.01), especially with alteplase (RR: 4.62; 95% CI: 1.33–16, p=0.02). In contrast, tenecteplase was associated with a more favorable safety profile, showing no significant increase in sICH (p=0.14). Conclusions Administering IVT after 4.5 hours can be a viable and effective option for selected AIS patients when guided by advanced imaging criteria, leading to improved recovery without increasing the risk of death Conflict of interest Nothing to declare