Objective: the study aimed to evaluate the value of the efficacy of the PA-TDI duration for predicting Perioperative atrial fibrillation in patients undergoing mitral valve surgery for mitral valve regurgitation. Methods: clinical and laboratory data of 100 patients who have mitral regurgitation and are planned for undergoing mitral valve surgery were collected and analyzed. Along with the usual echocardiographic parameters, PA interval measured by tissue Doppler was measured for all patients. Post-operatively, patients were followed up to detect occurrence of post-operative atrial fibrillation for one week post-surgery. Patients were divided into two groups according to incidence of POAF. The two groups were compared and PA-TDI was tested to assess its ability to predict POAF. Results: PA-TDI duration in POAF group was longer than in NO POAF group with highly significant difference between the two groups with P-value