A trial, simultaneously published online in Circulation and presented at the annual scientific sessions of the American Heart Association (AHA; 12–16 November, Orlando, Florida) has found that minimally invasive surgical ablation is more effective than catheter ablation but is also associated with more procedure-related adverse events
Surgical ablation, with the Cox maze approach, used to be the only available invasive treatment of atrial fibrillation. Although effective in selected patients, it was highly invasive. Therefore, it was superseded by catheter ablation. However, in 2006, Wolf et al (J Thorac Cardiovasc Surg 2005; 130: 797–802) described a minimally invasive approach to surgical ablation. Initial reports of this new approach indicated that it may have an efficacy of >90% in selected populations whereas a single-procedure catheter ablation was associated with an efficiency of >70% for paroxysmal atrial fibrillation (multiple procedures are usually required for long-standing persistent atrial fibrillation). Therefore, there has been growing debate about which should be the preferred option for invasive treatment of atrial fibrillation. Lead investigator of the new study, Lucas Boersma, Department of Cardiology, St Antonius Hospital, Nieuwegein, The Netherlands, who presented the study at the AHA scientific sessions, explained that the European Society of Cardiology only recommends minimally invasive surgical ablation if catheter ablation has failed. He added: “FAST (Atrial fibrillation catheter ablation versus surgical ablation) is the first randomised clinical trial that directly compares the efficacy and safety of catheter ablation to surgical ablation.”
The study evaluated the two approaches in 124 patients with atrial fibrillation (either persistent or paroxysmal) that was refractory to antiarrhythmic drugs. To be included in the study, they also had to have left atrial dilation of 40–44mm with hypertension, left atrial dilation ≥45mm, or haved undergone a previous failed catheter ablation procedure. According to Boersma, the important exclusion criteria were: “Long standing persistent (more than one year) atrial fibrillation, permanent atrial fibrillation, prior stroke or systemic embolism, significant valvular disease, left ejection fraction65mm.”
After being randomised in a 1:1 fashion, patients underwent either catheter ablation or minimally invasive surgical ablation. The catheter ablation procedure consisted of a wide-area linear antrum ablation with document pulmonary vein isolation with decapolar circular mapping catheter as the endpoint, and the surgical ablation procedure used video-assisted thoracoscopy. In the Circulation paper, Boersma et al reported: “In brief, pulmonary vein isolation was performed from the epicardial side with a bipolar radiofrequency ablation clamp. At least two overlapping applications around each of the ipsilateral veins were made, and isolation was confirmed by the absence of pulmonary vein potentials and exit block during pacing.” The primary efficacy endpoint of the study was freedom from atrial fibrillation (lasting more than 30 seconds) without the use of antiarrhythmic drugs 12 months after the procedure, and the primary safety endpoint was a significant adverse event (procedural or chronic) during the 12 months after the procedure.
The study found that surgical ablation was superior to catheter ablation in terms of the primary efficacy endpoint. Boersma said: “Looking at absolute differences, overall, after 12 months, about 37% of patients in the catheter ablation group were left free of atrial fibrillation but this figure was much higher in the surgical ablation group. About 66% of patients were free from arrhythmias in the surgical ablation group.”
However, the number of adverse events was significantly higher in the surgical ablation group compared with the catheter ablation group. Boersma explained: “Overall, the event rate was 34.4% in the surgical group and 15.9% in the catheter ablation group and this was primarily due to procedural complications.” In the surgical ablation group, procedure-related adverse events included pneumothorax, hematohorax, and pacemaker implantation. There were more chronic adverse events in the catheter ablation group (including stroke and death), but this difference was not significant (12.6% vs. 11.5%; p=1).
Boersma concluded: “I think these findings may be of use to physicians and patients when they have to choose optimal invasive therapy for atrial fibrillation.”