Cardiac rhythm and atrial transport function after surgical ablation of atrial fibrillation using cryoenergy: predictors and effectiveness of the procedure.

Aim: The aim of this prospective study was to assess the presence of sinus rhythm and atrial transport function after surgical ablation of atrial fibrillation using cryoenergy, and to evaluate predictors of the success of the procedure.

Methods: Between January 2005 and September 2006, 100 consecutive patients underwent left atrial cryoablation as a concomitant surgical procedure (46 patients with paroxysmal or persistent atrial fibrillation and 54 with permanent atrial fibrillation). Mitral valve surgery was performed in 74%. The mean and the median times of follow-up were 20 +/- 8.5, and 24 months respectively. Atrial mechanical function was assessed by echocardiography.

Results: Sinus rhythm was achieved during the postoperative follow-up in 71-81% of patients - significantly more often in the group with paroxysmal and persistent atrial fibrillation (90-98%), than patients with permanent atrial fibrillation prior to surgery (51-65%) (p<0.002). At 12 and 24 months after the surgery, a total of 68.2% and 51.2% of the patients were free from atrial fibrillation; 73.9% and 60.7% of the patients from the paroxysmal and persistent atrial fibrillation group, and 60.3% and 37.7% of patients with permanent atrial fibrillation (p=0.05). Five per cent of patients required postoperative permanent pacemaker implantation. An effective left and right atrial mechanical function was detected in 70-90%, and 96-98% of patients with sinus rhythm respectively. The following circumstances were identified as negative predictors of the presence of sinus rhythm after the ablation procedure: growing diameter of the left atrium, the duration of atrial fibrillation and the severity of mitral and tricuspid regurgitation before surgery (p<0.05). Restoration of the left atrial transport function was negatively predicted by the preoperative diameter of the left atrium, the presence of mitral valve stenosis and the severity of tricuspid regurgitation (p<0.05). A total of 95.4% of patients were free from stroke at one-year follow-up, and 94.1% at 2 years after surgery.

Conclusion: Stable sinus rhythm and effective left atrial transport function are the main factors resulting in decreased morbidity after successful ablation of atrial fibrillation. A careful post-operative follow-up of the patients and individualised treatment are necessary.