Abstract P387: Stroke Despite Anticoagulation Therapy Predicts Early Recurrence After Cardioembolic Stroke: The IAC-Study

Abstract

Background and purpose: A proportion of patients with ischemic stroke and atrial fibrillation (AF) have an ischemic stroke despite being prescribed anticoagulation therapy. In this study of patients with ischemic stroke in the setting of AF, we aim to determine the association between prior anticoagulant therapy and 90-day recurrent ischemic events and delayed symptomatic intracranial hemorrhage (sICH). Methods: We included consecutive patients with acute ischemic stroke and AF from the Initiation of Anticoagulation after Cardioembolic stroke (IAC) study from 8 comprehensive stroke centers in the United States. We compared recurrent ischemic events and delayed sICH risk using unadjusted and adjusted cox-regression analyses between patients who were prescribed anticoagulation (AC p ) vs. were naïve to anticoagulation therapy prior to the ischemic stroke (AC n ). For ischemic events, we adjusted for CHA 2 DS 2 -Vasc, anticoagulation initiation, and switching anticoagulant (DOAC to Warfarin or Warfarin to DOAC). For delayed sICH, we adjusted for age, sex, NIHSS score, and early hemorrhagic transformation. Results: 2070 patients had home anticoagulation treatment status recorded. When compared to the AC n group, the AC p group were more likely to have higher median (IQR) CHA 2 DS 2 -Vasc score [5 (4-6) vs. 5 (3-6), p = 0.001], lower NIHSS score [8 (3 - 18) vs. 10 (4 - 18), p = 0.015], severe left atrial enlargement (43.5% vs. 34.5%, p < 0.001), and less likely to receive alteplase (14.4% vs. 36.2%, p < 0.001). In the adjusted cox hazard model, AC p was associated with increased risk of 90-day recurrent ischemic events (adjusted HR 1.52 95% CI 1.01 - 2.29, p = 0.047) but not increased risk of 90-day sICH (adjusted HR 1.10 95% CI 0.46 - 2.61, p = 0.838). In a sensitivity analysis, with severe left atrial enlargement added to the model, the association between AC p and recurrent ischemic event risk did not meaningfully change (adjusted HR 1.41 95% CI 0.87 - 2.28, p = 0.162). Conclusion: Patients with AF and ischemic stroke despite being prescribed anticoagulation therapy are at higher risk of recurrent events. Studies are needed to understand mechanisms of ischemic stroke in these patients to improve stroke prevention strategies.