Efficacy and Safety of Intravenous Thrombolysis Beyond 4.5 Hours in Ischemic Stroke: A Systematic Review and Meta-Analysis

TL;DR

This study finds that intravenous thrombolysis can still help some stroke patients even after the 4.5-hour window, though it increases the risk of certain types of bleeding.

Contribution

The study provides updated evidence on the efficacy and safety of IVT beyond the standard 4.5-hour window using recent randomized trials.

Findings

IVT improved functional outcomes and neurological improvement in patients beyond 4.5 hours.

IVT increased the risk of symptomatic intracranial hemorrhage and parenchymal hemorrhage.

No significant increase in overall mortality or systemic bleeding was observed.

Abstract

Background: Intravenous thrombolysis (IVT) is the standard treatment for ischemic stroke within 4.5 h of symptom onset. However, a significant proportion of patients present beyond this window. This study aims to evaluate the efficacy and safety of IVT beyond the 4.5 h window in selected patients. Methods: A systematic literature search was conducted across PubMed, Cochrane Library, and Google Scholar from inception to April 2025. Odds ratios (ORs) with 95% confidence intervals (CIs) were pooled using a random-effects model. Results: A total of 12 RCTs were included, with 3236 patients. Compared to controls, IVT significantly improved excellent functional outcomes [OR: 1.40; 95% CI: 1.21–1.62] and good functional outcomes [OR: 1.26; 95% CI: 1.06–1.50] at 90 days. IVT also improved recanalization [OR: 2.47; 95% CI: 1.96–3.12], reperfusion [OR: 2.20; 95% CI: 1.26–3.84], and early neurological improvement [OR: 1.91; 95% CI: 1.12–3.26]. However, it was associated with a significantly higher risk of symptomatic intracranial hemorrhage (sICH) [OR: 2.17; 95% CI: 1.25–3.79], any ICH [OR: 1.49; 95% CI: 1.09–2.04], and type-II parenchymal hemorrhage (PH) [OR: 2.14; 95% CI: 1.19–3.83]. No significant difference was observed in systemic hemorrhage, 90-day all-cause mortality, 7-day mortality, or 90-day intervention-related mortality (p > 0.05). Conclusions: IVT beyond 4.5 h improves neurological outcomes in patients with ischemic stroke without increasing overall mortality or systemic bleeding, though it raises the risk of sICH, any ICH, and type-II PH. Further large RCTs are needed to confirm these findings and guide clinical practice.

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