Association of the Timing of Atrial Fibrillation Detection and Insular Involvement With the Risk of Embolic Events After Acute Ischemic Stroke

Objective Atrial fibrillation (AF) detected after insular stroke might arise from autonomic and inflammatory mechanisms triggered by insular damage, and be associated with a low embolic risk. We assessed the association of the timing of AF detection and insular involvement with the risk of embolic events after acute ischemic stroke. Methods Acute ischemic stroke patients with AF who underwent brain magnetic resonance imaging at baseline were enrolled. Patients were classified according to the timing of AF detection (AF detected after stroke [AFDAS] or known AF [KAF]) and insular involvement. The primary outcome was embolic events defined as recurrent ischemic stroke, transient ischemic attack, and systemic embolism within 90 days. Results Of 1,548 patients, 360 had AFDAS with insular cortex lesions (+I), 409 had AFDAS without insular cortex lesions (−I), 349 had KAF+I, and 430 had KAF−I. Cumulative incidence rates of embolic events at 90 days in patients with AFDAS+I, AFDAS−I, KAF+I, and KAF−I were 0.8%, 3.5%, 4.9%, and 3.3%, respectively. Patients with AFDAS−I (adjusted hazard ratio 5.04, 95% confidence interval 1.43–17.75), KAF+I (6.18, 1.78–21.46), and KAF−I (5.26, 1.48–18.69) had a significantly higher risk of embolic events than those with AFDAS+I. Interpretation Acute ischemic stroke patients with AFDAS and insular cortex lesions had a lower risk of embolic events than those who had AFDAS without insular cortex lesions or those with KAF, regardless of insular involvement. ANN NEUROL 2024;95:338–346