Background:Echocardiography is a clinical feasible method of choice for the quantitative analysis of left atrial appendage (LAA) mechanics in two dimensions. The study was to assess the potential relationship of left atrial appendage (LAA) mechanics parameters and left atrial appendage (LAA) function in patients with non-valvular atrial fibrillation (NVAF) by two-dimensional transesophageal echocardiography.Methods:This study involved 216 patients with Atrial Fibrillation ( 39.4%，woman) who were referred for a clinical indication for transesophageal echocardiography (TEE).Speckle-tracking was used to measure left atrial appendage mechanics (LAA) myocardial strain analysis. Left atrial appendage mechanical dispersions (LAAMD) were defined as the standard deviation (SD) of time to peak positive strain corrected by the R-R interval.Results:The Persistent atrial fibrillation（per-AF）group were older, higher prevalence of stroke, and more frequently suffered from heart failure than the Paroxysmal atrial fibrillation（par-AF）group. The patients with a lower LAAEF had less LAA mechanical dispersion than those with a higher LAAEF (4.82(2.66~6.82) vs 8.31(5.22~11.85) ,p＜0.05).The LAAMD had a significant positive correlation with the LAAEF (r=0.455).The LAAEF and LAAMD having the diagnostic performance (AUC,0.7397,95% CI 0.6692–0.8102, 0.6458, 95%CI 0.5678–0.7239, respectively). Using a LAAEF cut-off value of ＜64.5% and LAA MD cut-off value of ＜6.288%, patients with LAA dysfunction were identified with a sensitivity of 70.45%, 62.96% and specificity of 68.47%, 60.55%, respectively.Conclusions:The data showed that LAAMD was predictors of dysfunction of LAA, but LAAMD was not superior to LAAEF in patients for predictors LAA dysfunction. However, Left atrial appendage mechanical dispersion may showed decreased LAA function before LAA deformation