Objective To evaluate the efficacy of catheter ablation of atrial functional mitral regurgitation (AFMR) by two-dimensional speckle tracking imaging (2D-STI) combined with real-time three-dimensional echocardiography (RT-3DE), and to explore the influencing factors for the improvement of mitral regurgitation after catheter ablation.Methods Forty-seven patients with AFMR who underwent catheter ablation for the first time in our hospital were selected. All patients were reexamined by echocardiography at 6 months after ablation. According to whether AFMR improved after ablation, they were divided into improved group (22 cases) and non-improved group (25 cases). The left atrial diameter (LAD), mitral annular diameter (MAD), left ventricular end-systolic diameter (LVESD), left ventricular end-diastolic diameter (LVEDD) and left ventricular ejection fraction (LVEF) were measured by conventional echocardiography. 2D-STI was used to measure the left atrial storage period strain (LASr), pipeline period strain (LAScd) and pump period strain (LASct). The maximum left atrial volume (LAVmax) and minimum left atrial volume (LAVmin) were measured by RT-3DE, and the left atrial ejection fraction (LAEF) and left atrial dilatation index (LAEI) were calculated. The differences of the above parameters between the two groups before and after catheter ablation were compared to analyze the effect of catheter ablation on left atrial structure and function remodeling. Multivariate Logistics regression analysis was used to analyze the influencing factors of improvement of mitral regurgitation after catheter ablation. Receiver operating characteristic (ROC) curve was drawn to analyze the diagnostic value of each factor in predicting the efficacy of catheter ablation.Results Compared with those before catheter ablation, the cardiac structural parameters (LAD, MAD and LAVI) were decreased, and the functional parameters (LASr, LAScd, LASct, LAEF and LAEI) were increased after catheter ablation in the two groups, and the differences were statistically significant (all P < 0.05). Multivariate logistic regression showed that MAD (OR=5.552, 95% CI: 1.796-9.791, P=0.031), LASr (OR=0.733, 95% CI: 0.552-0.973, P=0.031) were independent predictors of improvement of mitral regurgitation after catheter ablation. ROC curve Compared with those before catheter ablation, the cardiac structural parameters (LAD, MAD and LAVI) were decreased, and the functional parameters (LASr, LAScd, LASct, LAEF and LAEI) were increased after catheter ablation in the two groups, and the differences were statistically significant (all P < 0.05). Multivariate logistic regression showed that MAD (OR=5.552, 95% CI: 1.796-9.791, P=0.031), LASr (OR=0.733, 95% CI: 0.552-0.973, P=0.031) were independent predictors of improvement of mitral regurgitation after catheter ablation. ROC curve analysis showed that the area under the curve of MAD for predicting improvement of mitral regurgitation was 0.775 (95% confidence interval: 0.643-0.908, P=0.001), and the best cut-off value was 3.35cm. The area under the curve of LASr for predicting improvement of mitral regurgitation was 0.735 (95% confidence interval: 0.643-0.908, P=0.001). 0.590-0.881, P=0.006), and the best cut-off value was 18.05%. analysis showed that the area under the curve of MAD for predicting improvement of mitral regurgitation was 0.775 (95% confidence interval: 0.643-0.908, P=0.001), and the best cut-off value was 3.35cm. The area under the curve of LASr for predicting improvement of mitral regurgitation was 0.735 (95% confidence interval: 0.643-0.908, P=0.001). 0.590-0.881, P=0.006), and the best cut-off value was 18.05%.Conclusion 2D-STI combined with RT-3DE can accurately evaluate the efficacy of catheter ablation in patients with AFMR. Both MAD and LASr are independent predictors of improvement of mitral regurgitation after catheter ablation.