Results of atrial fibrillation ablation during mitral surgery in patients with poor electro-anatomical substrate

Abstract

Background and aim of the study: Enlarged (> 50 mm) atria, longstanding (> 5 years) persistent atrial fibrillation (AF) and age > 70 years are considered predictive of recurrent AF following surgical ablation. The electrophysiological and clinical outcome after AF-ablation was evaluated in high-risk patients undergoing concomitant procedures.

Methods: Between January 2005 and January 2009, a total of 45 patients who complied with the three major predictors of failure, but who had undergone AF ablation ('left + right bipolar radiofrequency Maze') during concomitant mitral surgery were followed up. Freedom from AF, atrial flutter (AFL) and atrial tachycardia (AT), without anti-arrhythmic therapy (discontinued at the sixth month) was the primary endpoint. Survival, freedom from AF/AFL/AT with anti-arrhythmic therapy, early events during post-ablation blanking period, freedom from congestive heart failure (CHF) and from re-hospitalization, and changes in NYHA functional class were registered.

Results: Postoperatively, 18 patients (40%) showed sinus rhythm (SR) at admission to the intensive care unit, while 16 (26%) showed junctional rhythm and five (11%) required definitive pacemaker. Eleven of the 40 patients (28%) were discharged without a pacemaker, and experienced early events during the post-ablation blanking period. After a mean of 21 +/- 14 months' follow up, the actuarial survival was 88 +/- 7%. The prevalence of SR at six, 12, and 18 months was 74%, 64%, and 64% respectively. Freedom from AF/AFL/AT was 54 +/- 10% without anti-arrhythmic medications, and 51 +/- 9% with such drugs. Freedom from CHF was 85 +/- 6%, and significantly better in SR patients (94 +/- 6%) than in AF patients (69 +/- 13%; p = 0.018). Freedom from rehospitalization was 75 +/- 8%, and better in SR patients (94 +/- 6%) than in AF patients (37 +/- 14%; p = 0.0001). Accordingly, when compared to AF patients, the NYHA class was significantly ameliorated in SR patients at both six months (1.4 +/- 0.6 versus 2.7 +/- 0.9) and at the final follow up control (1.2 +/- 0.5 versus 1.9 +/- 0.7; p < 0.0001). The E/A wave recovered in 22 (85%) of the SR patients.

Conclusion: AF ablation during mitral valve surgery achieves good electrophysiological results, even in patients traditionally considered as poor candidates. SR recovery allows a higher freedom from CHF and rehospitalization, with a better functional recovery when compared to AF.