Objectives Left atrial (LA) dilation can evolve into asymmetrical remodeling. The aim of this study was to determine the echocardiographic parameters associated with LA asymmetric structural remodeling (ASR) in patients with and without nonvalvular atrial fibrillation (AF). Methods and results A total of 170 patients with a dilated LA were prospectively enrolled. ASR was defined as an atrium shape that is no longer ellipsoidal (LA basal dimension measured at the junction between the pulmonary vein and atrium greater than the mitral annular dimension). Symmetric structural remodeling (SSR) was defined as all other cases. Echocardiographic parameters of LA function and left ventricular diastolic function, measured by pulsed-wave Doppler and Tissue Doppler Imaging, were analyzed to identify the parameters associated with ASR. The mean age of the patients was 67 ± 11 years. Forty-one percent had a stable sinus rhythm (SR), and 59% had AF. LA-ASR was detected in 66% of the patients: 55% with AF and 45% with SR (p=0.002). The mean LA-ASR and LA-SSR volume indexes were 49 ± 14 ml/m² and 29 ± 13 ml/m², respectively (p<0.001). LA systolic myocardial velocity (p=0.036) and peak systolic pulmonary venous flow velocity (p=0.033) were the parameters best associated with ASR. The sensitivity and specificity of both parameters, based on ROC curve analysis, were 77 and 70%, respectively. The AUC was 0.765 (95% CI: 0.662-0.849, p=0.0001). Conclusion LA dilation is associated with asymmetrical structural remodeling. Echocardiographic parameters that reflect LA reservoir function are best associated with asymmetrical remodeling.