How effective is bipolar radiofrequency ablation for atrial fibrillation during concomitant cardiac surgery?

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was whether, in patients undergoing cardiac surgery, concomitant bipolar radiofrequency ablation had an acceptable success rate to justify the additional procedure. Altogether 263 papers were found using the reported search, of which 12 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. The consensus in the literature was that bipolar radiofrequency ablation was highly successful in restoring sinus rhythm. One meta-analysis of six non-randomized studies demonstrated that 76% of patients were in sinus rhythm compared with 16% in atrial fibrillation 3 months postoperatively. One randomized controlled trial found that the sinus rhythm conversion rate for any maze procedure was highly significant compared with the control group (P = 0.001). Another found that Cardioblate radiofrequency ablation was significantly better at restoring sinus rhythm at 1 year (75 vs 39% control, P = 0.019). Prospective studies showed a similar rate of sinus rhythm return at 1 year (89%). Notably some studies demonstrated a significant reduction in the New York Heart Association class when sinus rhythm was restored compared with those remaining in atrial fibrillation (P < 0.0001), demonstrating the value of this procedure beyond simply restoring sinus rhythm. In another study, the investigators found that both ablation and total procedure times were shorter with bipolar compared with monopolar ablation. These authors strongly recommend bipolar radiofrequency ablation due to a shorter procedure time, ability to avoid performing a standard left atriotomy and a greater guarantee of transmurality. With the current limited evidence, we conclude that bipolar radiofrequency ablation has a higher success rate in restoring sinus rhythm as an adjunct to cardiac surgery compared with no ablation for at least 1 year. The procedure had a high survival rate. There is randomized evidence to suggest the superiority of bipolar radiofrequency ablation over microwave ablation but limited evidence to suggest the superiority of bipolar over unipolar radiofrequency ablation. Factors found to be accurate predictors of ablation failure include a larger preoperative atrial diameter, permanent vs paroxysmal atrial fibrillation and longer duration of atrial fibrillation.