Surgical ablation of atrial fibrillation after the PRAGUE-12 study: more questions than answers.

No doubt surgical research has paved the way to curative treatment of cardiac arrhythmias. Long before the idea of catheter ablation was born, accessory atrioventricular pathways were interrupted by surgical knives, ventricular tachycardia was successfully treated by endocardial resection or scar circumcision, and even the first successful approaches to cure atrioventricular nodal re-entrant tachycardia were done in the surgical operating theatre. However, for these types of arrhythmias, surgical procedures are nowadays performed very rarely, mainly because of the tremendous success of catheter ablation. In atrial fibrillation (AF), current interventional treatment concepts and strategies would have been impossible without the milestone work of cardiac surgeons. The most important contribution came from James Cox and colleagues who established the Maze operation, the first curative treatment option for AF patients. In an attempt to replicate the Maze procedure with percutaneous catheters, John Schwarz initiated the development of catheter ablation procedures for AF in the early 1990s. Subsequently, and step by step, techniques and technologies were improved, and today catheter ablation is established as a leading treatment strategy for symptomatic patients with AF. In contrast, today stand-alone surgical ablation of AF does not play such a significant role. As indicated in a recent survey, failed catheter ablation currently is the most frequent indication for stand-alone surgical ablation. When compared with catheter ablation, surgical procedures are more invasive, more complex and complicated, and also more expensive. However, many patients with an indication for cardiac surgery because of coronary artery disease or valvular heart disease have or even suffer from AF. For these patients it may make sense to consider concomitant surgical ablation of AF during the same operation. Various non-randomized, mainly single-centre studies have shown that concomitant surgical ablation of AF significantly increased the sinus rhythm rate during short-term follow-up. Most of these studies have been done in centres experienced in arrhythmia surgery and have included highly selected patients, mainly those with symptomatic AF. However, only very little is known about the outcome of unselected patients with AF undergoing ablation during cardiac surgery. Budera and colleagues have now reported the 1-year outcome data from the PRAGUE-12 study, a multicentre, randomized, prospective evaluation of surgical ablation of AF in patients with an indication for cardiac surgery. A total of 224 patients were randomized to no ablation (n 1⁄4 107) or surgical ablation (n 1⁄4 117) concomitant with various other surgical procedures, mainly coronary artery bypass graft (CABG) and/or valvular surgery. Most importantly, patients were included regardless of AF-related symptoms or any other AF-specific selection criteria. The primary efficacy outcome parameter was freedom from AF during a single 24 h Holter electrocardiogram (ECG) recorded 1 year after ablation. The primary safety outcome parameter included 30 day perioperative complications. In the overall patient population, the authors observed a significantly higher sinus rhythm rate in the ablation group, while perioperative complications were similar in both groups. In addition, secondary outcome parameters such as total mortality, stroke rate, and the incidence of heart failure were not different between both groups. The PRAGUE-12 study addresses a very interesting and clinically highly relevant issue: does it make sense to perform surgical ablation of AF in an unselected patient cohort with an indication for cardiac surgery? Indeed, the unselected patient population included in the study seems to reflect closely routine clinical application of surgical AF ablation concomitant with other surgical interventions in Europe. The authors have to be congratulated for their efforts to investigate this patient population within the frame of a prospective, randomized, multicentre study. However, does the PRAGUE-12 study really help to better understand the outcome of surgical ablation in an unselected population? Does the