Background:Left atrial(LA) fibrosis and reverse remodeling are important prognostic factors after mitral valve(MV) surgery. We sought to investigate predictors of fibrosis and reverse remodeling using speckle tracking imaging in patients with MV disease who underwent MV surgery. Methods:Fifty patients who had planned to MV surgery (28 with predominant mitral stenosis and 22 with mitral regurgitation) underwent comprehensive echo-Doppler evaluation. Global strain and strain rate of LA were measured in apical 4- and 2-chamber views using 2D speckle tracking image analysis (n=17). During operation LA tissues were obtained and then degree of fibrosis (% of fibrosis area) was measured after trichrome staining. Seven to fifteen days after MV surgery, the reduction of LA volume was evaluated. Results: Degree of LA fibrosis was higher in patients with predominant mitral stenosis (36.5짹20.4% vs. 20.1짹11.0% for mitral regurgitation, p=0.001) and atrial fibrillation (n=32, 33.7짹18.0% vs. 21.5짹17.8% for sinus rhythm, p=0.025). Also, average LA global strain (9.6짹4.3 vs 18.0짹7.2 %, p<0.001) and preoperative systolic global strain rate (0.41짹0.17 vs 0.75짹0.27 s-1, p<0.001) representing reservoir function of LA were higher in patients with mitral regurgitation compared to mitral stenosis. Average LA global strain was significantly correlated with degree of fibrosis (r=-0.550, p=0.022), and LA systolic global strain rate was significantly correlated with degree of LA volume reduction (��=-0.715, p=0.003) after surgery independent of age, presence of atrial fibrillation (AF), preoperative predominant pathology or modality of valve surgery. Conclusions: Preoperative global LA strain and systolic global LA strain rate measured by speckle tracking imaging could predict the degree of LA fibrosis and postoperative LA volume reduction in patients with MV disease. Keywords: Speckle tracking imaging, mitral valve surgery, fibrosis, reverse remodeling