Background: Intravenous thrombolysis (IVT) is an effective way for treating acute ischemic stroke (AIS). However, its effects have not been established among AIS patients with unclear stroke symptoms or with stroke onset for >4.5 h.
Methods: We searched PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials and Google Scholar databases for randomized controlled trials that compared IVT (IVT group) and placebo or usual care (control group [CG]) in AIS patients with disease onset for >4.5 h. The outcomes of interest included the favorable functional outcome (defined as modified Rankin Scale [mRS] scores 0-1) at 90 days, the functional independence (defined as mRS scores 0-2) at 90 days, proportion of patients with symptomatic intracerebral hemorrhage (sICH) and death at 90 days. We assessed the risk of bias using the Cochrane tool. Pre-specified subgroup analyses were performed by age (≤70 years or >70 years), National Institute of Health Stroke Scale (NIHSS, ≤10 or >10) and time window (4.5-9.0 h or >9.0 h).
Results: Four trials involving 848 patients were eligible. The risk of bias of included trials was low. Patients in the IVT group were more likely to achieve favorable functional outcomes (45.8% vs. 36.7%; OR 1.48, 95% CI 1.12-1.96) and functional independence (63.8% vs. 55.7%; OR 1.43, 95% CI 1.08-1.90) at 90 days, but had higher risk of sICH (3.0% vs. 0.5%; OR 5.28, 95% CI 1.35-20.68) at 90 days than those in the CG. No significant difference in death at 90 days was found between the two groups (7.0% vs. 4.1%; OR 1.80; 95% CI 0.97-3.34).
Conclusions: Use of IVT in patients with extended time window may improve their functional outcomes at 90 days, although IVT may induce increased risk of sICH. Care of these patients should well balance the potential benefits and harms of IVT.
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