Argentina: A recent systematic review and meta-analysis published in theJournal of Thrombosis and Thrombolysiscompared early versus delayed initiation oforal anticoagulation (OAC)for secondary stroke prevention in patients withatrial fibrillation (AF)following anacute ischemic stroke (AIS).The study, conducted by Vinicius Pereira and colleagues from the Faculty of Biomedical Sciences, Universidad Austral, Argentina, pooled data exclusively from randomized controlled trials (RCTs), providing updated evidence on this critical clinical question. Patients with AF who experience AIS are at heightened risk of recurrent strokes, making timely initiation of anticoagulation vital. However, the ideal window to start OAC therapy remains debated due to concerns over bleeding complications, particularly intracranial hemorrhage. The inclusion of the recently completed OPTIMAS trial, the largest RCT to date on this topic, adds considerable weight to the findings. The researchers systematically reviewed PubMed, Scopus, and Cochrane Central databases up to October 2024, identifying three RCTs encompassing 6,442 participants. Of these, 50.17% received early OAC. Using the Mantel–Haenszel method, pooled odds ratios (ORs) with 95% confidence intervals (CI) were calculated for major outcomes. The key findings of the study were as follows: The authors concluded that starting OAC soon after AIS in AF patients appears to be safe, as it does not significantly increase bleeding or mortality risks. However, its overall efficacy in reducing recurrent strokes remains inconclusive, with possible benefits restricted to select patient subgroups. The inclusion of OPTIMAS bolsters the current evidence base and supports individualized decision-making until more extensive data are available. "Clinicians are advised to weigh the risks and benefits of early anticoagulation on a case-by-case basis, considering patient-specific factors such as stroke severity, bleeding risk, and comorbidities. Further large-scale trials are necessary to refine guidelines and clarify which patient populations may benefit most from early intervention," the authors wrote. Pereira, V., Marino, M., Hornik, A. et al. Comparison of early vs late anticoagulation for secondary stroke prevention in patients with atrial fibrillation: a systematic review and meta-analysis of randomized controlled trials. J Thromb Thrombolysis (2025). https://doi.org/10.1007/s11239-025-03139-6