Bipolar versus unipolar energy in the surgical ablation of atrial fibrillation in patients with mitral valve surgery

Objective: To evaluate the presence of sinus rhythm or atrial fibrillation (AF) in patients who had mitral valve surgery with concomitant surgical ablation of AF, by unipolar or bipolar radiofrequency. Methods: Adults patients who had mitral valve replacement or mitral valvuloplasty with concomitant surgical ablation of AF, either by unipolar or bipolar radiofrequency, were consecutively included between the 2008 and 2012. Surgery was done by conventional median sternotomy. Results: A total of 99 patients were included; 20 (20.2%) had surgical ablation by unipolar energy and 79 (79.8%) by bipolar energy. There were 76 (76.8%) women, and mean age± SD was 51 ±11 years. The median duration of AF before surgery was 41 months. Type of AF was paroxysmal in 21 (21%), persistent in 11 (11%), and long-standing persistent in 67 (67%). Mean left atrium size in the preoperative period was 5.54 ± 0.82 cm. Mean left ventricular ejection fraction was 58±12.4%. Types of mitral valve surgery were valvuloplasty (n=10), mechanical valve replacement in 30, and bioprosthesis replacement in 59. Concomitant tricuspid annuloplasty was performed in 39 patients. Thirty- day mortality was 8/99 (8%). Mean follow-up time was 1274 days (3.49 years). Survival was 92%. After 4 years no patient who had had unipolar ablation was in sinus rhythm, whilst 67% of those who had bipolar energy ablation were in sinus rhythm (p<0.001). Conclusion: The use of bipolar energy is superior to unipolar energy in the surgical ablation of atrial fibrillation in patients submitted to mitral valve surgery.