ABSTRACT NUMBER: ESOC2026LB72 CHARACTERISTICS OF PATIENTS WITH ISCHEMIC STROKE DESPITE ORAL ANTICOAGULATION FOR ATRIAL FIBRILLATION

Abstract Background and aims Breakthough ischemic stroke despite oral anticoagulation (OAC) among patients with atrial fibrillation (AF) remains insufficiently characterized. We aimed to identify characteristics associated with ischemic stroke despite OAC treatment. Methods Prospective data from consecutive patients with ischemic stroke and AF who underwent carotid imaging from 10 stroke registries were included. Patients were categorized in those with i)stroke despite OAC, ii) known AF not on OAC, iii) newly diagnosed AF. Multivariable logistic regression was performed to identify clinical characteristics associated with stroke despite OAC. Results Among 2,551 stroke patients, 30.1% experienced a breakthrough stroke, 32.0% were not receiving OAC despite AF history, and 37.9% had newly diagnosed AF. Patients with breakthrough were older, had a higher cardiovascular comorbidity burden, and presented with milder neurological deficits compared to those not on OACs. Ipsilateral atherosclerotic carotid stenosis was more prevalent in the OAC group (p=0.008). Compared to those not treated with OACs, characteristics associated with breakthrough stroke included increasing age (aOR:1.02/year; 95%CI:1.00–1.03), prior stroke/TIA (aOR:1.67; 1.13–2.47), persistent/permanent AF (aOR:1.49; 1.11–2.01), multiterritorial infarcts (aOR:2.04; 1.27–3.25), hyperlipidemia (aOR:1.4; 1.05–1.90), and cancer (aOR:2.73; 1.10–6.76). Mild ipsilateral carotid stenosis was associated with breakthrough stroke (aOR:1.37; 1.00–1.86), even though stenosis >50% were not associated with breakthrough stroke. Conclusions Breakthrough strokes were associated with older age and higher cardiovascular risk burden. These findings suggest the presence of competing stroke mechanisms beyond cardioembolism and underscore the need for comprehensive vascular risk assessment. Conflict of interest