Reduced Left Atrial Appendage Flow Velocity as a Risk of Thromboembolic Events After Catheter Ablation of Atrial Fibrillation

Background Reduced left atrial appendage flow velocity (LAAFV) on transesophageal echocardiography (TEE) is recognized as a predictor of thromboembolic events (TEs) in patients with atrial fibrillation (AF). However, its long‐term prognostic value following AF ablation remains unclear. Methods and Results We retrospectively evaluated 1521 patients undergoing AF ablation who underwent preprocedural TEE. Patients were categorized into two groups based on LAAFV: reduced (≤ 21.4 cm/s, n = 99) and preserved (> 21.4 cm/s, n = 1422). The primary outcome was TEs. Secondary outcomes included arrhythmia recurrence and major adverse cardiovascular events (MACEs), defined as a composite of all‐cause death, stroke, major bleeding, and heart failure hospitalization, as well as individual components and cardiovascular mortality. Over a mean follow‐up of 49 ± 32 months, TEs occurred in 19 patients (1.2%). The 5‐year cumulative incidence of TEs was significantly higher in the reduced LAAFV group (6.7% vs. 0.9%, p < 0.0001), despite a lower rate of anticoagulation discontinuation (20.1% vs. 57.1%, p < 0.0001). Multivariable analysis identified reduced LAAFV as an independent predictor of TEs. It was also associated with higher risks for all secondary endpoints. Conclusions Reduced preprocedural LAAFV is associated with adverse long‐term clinical outcomes after AF ablation, including a significantly increased risk of thromboembolic events.