['Recurrence after catheter ablation of persistent atrial fibrillation (AF) remains an unsolved issue. This study aimed to explore the association between the left atrial appendage peak flow velocity (LAAV) and AF recurrence after ablation in persistent AF patients.', 'Fifty-three consecutive patients who underwent an initial catheter ablation of persistent AF were enrolled [age, 65±10 years; male, 42 (79%)]. The LAAV was obtained by transesophageal echocardiography before ablation. All the patients underwent pulmonary vein isolation and were followed up for 12 months. The LAAV and other clinical factors (AF duration, CHA2DS2VASc score, left atrial diameter, left atrial volume, and left ventricular ejection fraction) were tested using a Cox proportional hazards regression analysis as predictors of AF recurrence during the 1-year follow-up.', 'AF recurrence occurred in 16 (30%) patients. The patients with AF recurrences had lower LAAVs (23.3±7.2cm/s vs. 33.3±15.1cm/s, p=0.002) than those without AF recurrence. In the multivariable analysis, a low LAAV independently predicted AF recurrence (hazard ratio, 3.04; 95% confidence interval, 1.05-8.79; p=0.040). A Kaplan-Meier analysis also demonstrated a lower survival rate free from AF recurrence in the low LAAV group than in the high LAAV group (p=0.030).'] Does low left atrial appendage flow velocity predict recurrence of atrial fibrillation after catheter ablation of persistent atrial fibrillation?