Left atrial (LA) strain is a sensitive measure of LA mechanics. However, its relationship with rhythm outcomes after catheter ablation in patients with atrial fibrillation (AF) is not well established. The aim of this study was to evaluate whether baseline LA global longitudinal strain (LAε) predicts rhythm outcomes in patients who undergo catheter ablation for AF.In 256 patients with AF (paroxysmal, 204; persistent, 52), comprehensive echocardiography was performed with assessment of LAε by using Velocity Vector Imaging to calculate average strain values from apical four- and two-chamber views before ablation (median, 41 days; interquartile range, 1-95 days).After a median of 8.0 months (interquartile range, 4.0-23.3 months) of follow-up, 149 patients (58%) had maintained sinus rhythm and 107 patients (42%) had recurrence of AF. In our study cohort (mean age 59 ± 11 years; mean left ventricular ejection fraction, 58 ± 10%), impaired total LAε (LAεtotal) was associated with greater left ventricular mass index (r = -0.245, P < .001) and worsening left ventricular diastolic function (ratio of transmitral flow peak early diastolic velocity to peak early diastolic velocity of the mitral annulus: r = -0.357, P < .001; maximal LA volume index: r = -0.393, P < .001). Patients with LAεtotal < 23.2% showed a higher incidence of AF recurrence compared with patients with LAεtotal ≥ 23.2% (log-rank P < .001). In multivariate Cox proportional-hazards analysis, LAεtotal was independently related to rhythm outcomes (hazard ratio, 0.944; 95% confidence interval, 0.915-0.975; P < .001) after AF ablation. Moreover, LAεtotal provided incremental predictive value for rhythm outcomes over clinical features (increment in global χ(2) = 14.63, P < .001).In patients with AF, baseline LAεtotal was associated with rhythm outcome after catheter ablation.