ObjectiveTo investigate the restoration of left atrial function and its relationship with atrial fibrosis of patients after mitral valve replacement (MVR)and concomitant radiofrequency ablation (RFA)for atrial fibrillation (AF). MethodsClinical data of 32 patients with mitral valve disease and chronic AF who underwent surgical treatment in General Hospital of Shenyang Military Area Command from January to August 2010 were retrospectively analyzed in this cohort study. There were 11 male and 21 female patients with their age of 49.8±8.7 years. There were 14 patients with rheumatic mitral stenosis (MS), 8 patients with rheumatic MS and mitral regurgitation, and 10 patients with mitral valve prolapse. Preoperative AF duration was 3.6±4.6 years. All the patients received MVR and concomitant RFA for AF. According to the cutting off extent of left atrial fibrosis (10.9%), all the 32 patients were divided into 2 groups. There were 19 patients with more severe left atrial fibrosis ( > 10.9%)in group A and 13 patients with milder left atrial fibrosis ( < 10.9%)in group B. Immunohistochemistry was performed to examined left atrial fibrosis, and echocardiography was performed to examined the structure and function of left atrium. ResultsThere was no perioperative death. Cardiopulmonary bypass time was 84.6±22.6 minutes, aortic cross-clamping time was 47.6±15.6 minutes, and ICU stay was 3.2±1.5 days. All the 32 patients were followed up for longer than 6 months (1.3±0.6 years). The extent of left atrial fibrosis of the 32 patients was 4.8%-18.3% (10.7%±4.2%). There was no statistical difference in left atrial diameter (LAD), left atrial fractional area change (LAFAC)or mitral annular motion between group A and group B preoperatively and 3 months after surgery respectively (P > 0.05). At 6 month after surgery, LAD of group B was significantly smaller than that of group A (P < 0.05), late diastolic mitral annular velocity (Am)of group B was significantly higher than that of group A (P < 0.05), and there was also some improvement in LAFAC of group B compared with group A (P=0.067). Among the 32 patients, 28 patients (87.5%)restored sinus rhythm (SR)3 months after surgery, and 21 patients (65.6%)maintained SR longer than 6 months after surgery. Patients in group B were more likely to maintain SR than patients in group A (P=0.010). ConclusionImprovement of left atrial function can be observed 6 month after MVR and concomitant RFA for AF, which is related to the extent of left atrial fibrosis.