ABSTRACT NUMBER: ESOC2026A2461 ACUTE ISCHEMIC STROKE IN PATIENTS WITH ATRIAL FIBRILLATION DESPITE ADHERENCE TO APPROPRIATE ORAL ANTICOAGULATION

Abstract Introduction Atrial fibrillation (AF) causes 20-30% of acute ischemic strokes (AIS). Despite adherence to oral anticoagulants (OAC), embolic events still occur. We aim to characterize AF patients with AIS while on adequate OAC therapy. Methods Retrospective observational study of consecutive inpatients with AIS and AF between January 2023 and December 2024. Clinical-demographic data, including AF characteristics, vascular risk factors, treatment and stroke etiological investigation results were analysed. Results Of 242 patients with AIS and AF, 64 (26.4%) suffered a stroke, despite an appropriately dosed and compliant OAC regimen. They were 51.6% female, median age 82 years. The majority (78.1%) had permanent AF, and apixaban was the commonest OAC (n=25, 39.1%). Forty (62.5%) completed aetiologic investigation. In 21.9% another concomitant cause of stroke was found, most often intracranial and/or extracranial great vessel atherosclerotic stenosis/occlusion was present in eight (12.5%). Another 11 (17.2%) patients had more cardioembolic causes, as mechanic valvular prosthesis (6.2%) or left ventricular hypokinesia (4.7%). Either hypertension, dyslipidaemia, or diabetes was uncontrolled in 34 (54%) patients, but without another specific stroke cause. In the end, AF was the sole aetiology found in 12 (18.8%) adequately anticoagulated patients, with controlled vascular risk factors. Conclusion A quarter of AF patients with AIS were compliant with appropriate AOC. Not all were offered aetiological investigation. In those who were, multiple aetiologies were found in 22%, and concomitant cardioembolism in 17%. There remain 20-40% of patients with just AF, who could benefit from add-on therapies, like left atrial appendage occlusion. Conflict of interest Nothing to disclose