Timing of Anticoagulant Initiation After Moderate-Severe and Severe Acute Ischemic Strokes (TAMSS)

Background: Optimal timing for initiating anticoagulation after acute ischemic stroke remains uncertain, requiring a balance between thromboembolic prevention and minimizing the risk of hemorrhagic transformation. Aims: To compare the safety and efficacy of early versus late anticoagulation initiation after acute ischemic stroke. Methods: Retrospective chart review at a tertiary medical center evaluating early (≤7 days from stroke onset) or late (>7 days from stroke onset) anticoagulation initiation for adults admitted to the Neurological Critical Care Unit between January 1, 2019 and June 1, 2024 with an indication for anticoagulation and a diagnosis of moderate-severe or severe acute ischemic stroke. Results: Primary outcome was a composite of major extracranial bleeding and symptomatic intracranial hemorrhage within 30 days of anticoagulation initiation. Of 356 patients screened, 143 met inclusion criteria; 91 (64%) received early and 52 (36%) received late anticoagulation. Baseline demographics were similar between the cohorts. Primary 30-day outcome occurred in 12% (11/91) of the early and 10% (5/52) of the late cohort ( P = 0.78). No differences were observed in bleeding events, recurrent stroke, embolism, or mortality at 30 or 90 days. On multivariable analysis, P2Y12 inhibitor use was associated with increased risk of the primary outcome (OR 5.241, 95% CI 1.295-21.206, P = 0.02). Conclusions and Relevance: Early anticoagulation after ischemic stroke was not associated with higher bleeding risk and may reduce hospital stay, suggesting that early initiation may be safe. Larger prospective studies are needed to determine optimal timing of anticoagulation.