Background: Permanent atrial fibrillation (AF) is present before operation and persists after surgery in 30-40% of patients undergoing mitral valve surgery. Using the maze procedure, 75-82% of patients can be cured of AF, but the procedure is difficult and long lasting. Percutaneous radiofrequency (RF) ablation has emerged as an effective therapy for AF in recent years.
Aim: To assess the efficacy of intra-operative RF ablation of AF in patients undergoing mitral valve surgery.
Methods: 100 adults with permanent AF underwent mitral valve replacement. Patients were divided into two groups: the RF group – 50 patients qualified for mitral valve replacement and RF ablation; and the control group – 50 patients selected for mitral valve replacement without ablation. Odds ratio and 95% confidence interval were examined to assess the influence of several factors on the outcome (free from AF during one-year follow-up based on symptoms and serial Holter ECG recordings).
Results: Baseline clinical, demographic and echocardiographic characteristics were similar in both groups. Electrical cardioversion following surgery was required in 76% of patients from the RF group compared with 94% from the control group (p <0.002). In those who underwent cardioversion, sinus rhythm was restored more frequently in RF than control patients (32 vs. 16%, p <0.002). Sinus rhythm at hospital discharge was present in 56% of RF patients compared with 22% of controls (p=0.0001), and after one-year follow-up in 54 vs. 16% (p <0.001), respectively. The use of amiodarone was significantly lower in RF patients compared with controls (32 vs. 70%, p <0.05). NYHA class III (OR 8.5, CI 1.0-394) or IV (OR 36, CI 1.2-1958) and left atrial diameter >6 cm (OR 9.3, CI 0.5-5230) were identified as predictors of AF.
Conclusions: Intra-operative RF ablation performed in the left atrium in patients with chronic AF undergoing mitral valve replacement significantly improves sinus rhythm restoration rate. Advanced heart failure (NYHA class IV) and left atrial diameter >6 cm are negative prognostic factors for sinus rhythm maintenance.