Abstract WP083: Predisposition to Atrial Fibrillation in ESUS Stroke Population with Large Vessel Occlusion

Introduction: Large vessel occlusion (LVO) is a common presentation of acute ischemic stroke. However, many patients with LVO are ultimately discharged with a stroke etiology classified as an embolic stroke of undetermined source (ESUS). It is suspected that a significant proportion of these patients may have underlying atrial fibrillation (AF) that remains undetected at the time of discharge. Identifying AF in this population has important implications for long-term management, which can significantly reduce risk of recurrent stroke. This study aims to evaluate patients with LVO classified as ESUS and determine the incidence of atrial fibrillation development within this group. Methods: This was a single-center, retrospective analysis of patients presenting with large vessel occlusion (LVO) who underwent mechanical thrombectomy between 2016 and 2023 with ESUS stroke etiology at discharge. Univariable logistic regression was used to assess cardiac and large-vessel factors associated with subsequent atrial fibrillation (AF). Patients with AF at presentation or left ventricular ejection fraction <30% were excluded. Additionally, rates of stroke recurrence were compared between patients discharged on antiplatelet therapy versus anticoagulation Results: Of 112 patients, 36 (32.1%) were ultimately diagnosed with AF, either before or after discharge. Among the 90 patients discharged without AF diagnosis, 14 (15.6%) were later diagnosed during follow-up. Fourteen patients with post-discharge AF experienced recurrent stroke; of these, 12 (85.7%) were on antiplatelet therapy (single or dual antiplatelet) and 2 (14.3%) were on anticoagulation at the time of recurrence. There was a trend toward association between moderate left atrial enlargement and AF development (odds ratio 8.75, 95% CI 1.73–44.16; p = 0.009). Conclusion: About 15% of patients with LVO classified as ESUS were diagnosed with AF after discharge. All had orders for extended cardiac monitoring, highlighting the importance of post-discharge monitoring. A trend toward left atrial enlargement and AF development was observed, and larger studies are needed to better define patients at highest risk.