Objective   To investigate the safety and medium- and long-term efficacy of surgical radiofrequency ablation to treat atrial fibrillation during concomitant mitral valve surgery.

  Methods   From January 2014 to December 2018, 280 patients with mitral valve disease and the comorbidity of preoperative atrial fibrillation were recruited for the study. Among them, 130 patients received only mitral valve surgery (non-ablation group), and 150 patients were underwent surgical radiofrequency ablation for the atrial fibrillation during concomitant mitral valve surgery (ablation group). Among the 150 patients of the ablation group, 80 had biatrial ablation, and 70 had left atrial ablation. Under general anesthesia, median sternotomy was done on all patients and cardiopulmonary bypass was established through the ascending aorta and superior and inferior venae cavae. After aortic occlusion, patients in the ablation group underwent the ablation procedure with the Atricure® bipolar ablation device, using the Cox Maze Ⅲ procedure as a reference. In addition, the left atrial appendage was removed and electrocautery of the ligament of Marshall and Waterston’s groove were performed in all Cox Maze cases. Following ablation, mitral valve replacement or repair was performed. All patients were given 200 mg oral amiodarone on the first day after surgery, for three times/d×7 d, which was followed by twice/d×7 d, and then oral amiodarone 200 mg/d was maintained till the end of 3 months after surgery (ablation group) or 12 months after surgery (non-ablation group). Patients were followed up at the intervals of 3 months, 6 months, 12 months, 2 years, 3 years, and 5 years after discharge. The follow-up service included standard 12-lead chest electrocardiogram (ECG) and 24-h dynamic ECG. The primary end point of the study was the time point of postoperative atrial fibrillation and the secondary endpoints were major cardiovascular events, death, and readmission due to heart failure.

  Results   The surgeries were successfully performed in all subjects of the study. A total of 30 patients were lost to follow-up within 5 years after operation (10.7% losses to follow-up), including 11 patients in the ablation group and 19 patients in the non-ablation group. The proportion of patients who did not have atrial fibrillation in the ablation group and the non-ablation group at 6 months, 12 months, 2 years, 3 years and 5 years after surgery was 83.3% and 27.7%, 72.7% and 20.8%, 66.0% and 15.4% 61.3% and 13.1%, and 43.3% and 10.8%, respectively, with the data from the two groups showing statistically significant difference (P<0.001). The proportion of patients who did not have atrial fibrillation in the biatrial ablation and the left atrial ablation group at 6 months, 12 months, 2 years, 3 years and 5 years after surgery was 87.3% and 87.5%, 92.4% and 82.8%, 90.5% and 85.7%, 94.8% and 88.1%, and 75.5% and 69.4%%, respectively, with the data from the two groups showing no statistically significant difference (P>0.05). However, the cumulative incidence of atrial fibrillation in the two groups showed statistically significant difference (P<0.001). There were no deaths within 30 days after operation in either group. There was no significant difference in cerebrovascular accident, readmission for heart failure, pulmonary infection and mediastinal infection between the two groups within one year after operation (P>0.05). However, the proportion of patients who had permanent pacemaker installed due to Ⅲ-degree atrioventricular block in the ablation group was higher than that in the non-ablation group (P<0.05). The proportion of patients who required re-drainage due to delayed pericardial effusion in the ablation group was higher than that in the non-ablation group (P<0.05).

  Conclusion   In the group of patients who had modified Cox Maze procedure with bipolar ablation device to treat atrial fibrillation during concomitant mitral valve surgery, the maintenance rate of sinus rhythm after cardioversion was significantly higher than that in the non-ablation group. The surgery showed better safety and significantly better medium- and long-term outcomes. Left atrial ablation and biatrial ablation were both considered safe and effective surgical treatment for atrial fibrillation. Compared with the left atrial ablation group, the biatrial ablation group achieved better effects in restoring and maintaining sinus rhythm without an increase the incidence of perioperative complications.