ABSTRACT NUMBER: ESOC2026A1093 STROKE IN PATIENTS WITH ATRIAL FIBRILLATION DESPITE ORAL ANTICOAGULATION – A MULTICENTER ANALYSIS

Abstract Background and aims Secondary stroke prevention in patients with atrial fibrillation (AF) who experience acute ischemic stroke (AIS) despite oral anticoagulation (OAC) is challenging. The aim of this analysis was to characterize patterns and competing causes of AIS in patients with AF with and without OAC. Methods We retrospectively analyzed all patients admitted with AIS and known AF to three tertiary care hospitals in Berlin, Germany in 2024 and compared (1) those with and without OAC and (2) adequate vs. insufficient OAC dosing. Comparisons included markers of small vessel disease (SVD) on MRI and competing stroke etiologies according to the TOAST-classification. Results We included 249 AIS patients (mean age 80.5 years, median NIHSS=5, 52.6% female) of which 172 (69.1%) had OAC, including 75/172 (39.5%) with insufficient dosing. Patients with AIS despite OAC less frequently had large vessel occlusions (41.4% vs. 55.8%; p=0.033), but more frequently had active cancer (9.3% vs. 1.3%; p=0.021) and a competing stroke etiology (28.5% vs. 14.3%; p=0.015). Competing etiologies included large artery atherosclerosis [16/49 (32.7%)], SVD [13/49 (26.5%)] and concomitant malignancy [15/49 (30.6%)]. Patients with OAC more often had presence of lacunes (32.6% vs. 15.4%; p=0.037), while other SVD components did not differ. With regard to insufficient OAC dosing competing etiologies did not differ significantly (33.3% vs. 22.7%; p=0.128). Conclusions In AIS with AF despite OAC, competing etiology and insufficient dosing was common. Of note, 1 in 3 patients with competing etiology had concomitant malignancy. Individualized and novel preventive strategies are needed to reduce future ischemic stroke risk. Conflict of interest Sophie Böhme: nothing to disclose. Noah Ayadi: nothing to disclose. Regina von Rennenberg: nothing to disclose. Markus Klammer: Nothing to disclose. Thea Hüsing: received travel and accommodation costs from Jazz Pharmaceuticals. Jan Scheitz: received honoraria for lectures/consulting fees from AstraZeneca, Bristo-Myers Squibb and Medtronic. Heinrich Audebert: received honoraria for lectures/advisory boards from AstraZeneca, Bayer, BMS, Boehringer and Pfizer. Christian Nolte: received honoraria for lectures/advisory board from AstraZeneca, Bayer and Pfizer.