Atrial Fibrillation Catheter Ablation Versus Surgical Ablation Treatment (FAST) A 2-Center Randomized Clinical Trial
Editor's Note: This article is based on Boersma LV, Castella M, van Boven W, Berruezo A, Yilmaz A, Nadal M, et al. Atrial Fibrillation Catheter Ablation Versus Surgical Ablation Treatment (FAST): A 2-Center Randomized Clinical Trial. Circulation 2012;125: 23-30.
This two-center prospective randomized study was designed to compare the efficacy and safety of radiofrequency catheter ablation (CA) versus minimally-invasive surgical ablation (SA) in specific subgroups of patients with symptomatic atrial fibrillation (AF) refractory to at least 1 antiarrhythmic drug. The inclusion criteria were left atrial (LA) diameter of 40-44 mm in association with hypertension, LA diameter ≥45 mm, or a prior unsuccessful CA procedure. Exclusion criteria included long-standing persistent AF, LA diameter >65 mm, and left ventricular ejection fraction <45%.
Neither the CA nor the SA strategy was uniform between the 2 centers. At 1 of the centers, the CA strategy consisted only of circumferential antral ablation to isolate the pulmonary veins using a standard 4-mm-tip radiofrequency ablation catheter and the SA strategy consisted of a video-assisted thoroscopic approach, epicardial pulmonary vein isolation using a bipolar radiofrequency ablation clamp, bilateral epicardial ganglia ablation, and additional LA ablation lines at the operator’s discretion. At the other center, antral pulmonary vein isolation was performed using a 3.5-mm irrigated-tip ablation catheter, along with additional LA ablation lines at the discretion of the operator, and the SA strategy consisted of pulmonary vein isolation with the bipolar radiofrequency ablation clamp, isolation of right atrial ganglionated plexi, and surgical division of the ligament of Marshall. The LA appendage was excised in all SA patients. Antiarrhythmic drug therapy was discontinued after a 3-month blanking period. Cardioversion was permitted during the blanking period.
A 7-day Holter monitor was performed pre-ablation and at 3, 6, and 12 months of follow-up. The 1º efficacy end point was freedom from any LA tachyarrhythmia lasting >30 seconds during 3-12 months of follow-up in the absence of antiarrhythmic drug therapy. The 1º safety end point was the rate of significant adverse events (SAEs) during 12 months of follow-up.
One-hundred twenty-four patients (mean age 56 years, mean LA diameter 43 mm) with AF (paroxysmal in 67%) were randomly assigned to CA (n=63) or SA (n=61). A prior unsuccessful CA procedure had been performed in 67% of patients. The baseline Holter monitor demonstrated no AF in 48% of patients, paroxysmal AF in 20%, and continuous AF in 32%. In the CA group, a LA ablation line was made at the roof in 48% of patients, at the mitral isthmus in 27%, and at both sites in 23%. In the SA group, additional lines were created in 31% of patients.
The 1º efficacy point at 12 months of follow-up was achieved significantly more often in the SA group (65.6%) than in the CA group (36.5%). Efficacy was not significantly different between the 2 study sites and was not affected by the use of an irrigated-tip catheter or the creation of supplementary ablation lines.
The primary safety end point of SAEs was significantly higher in the SA group (34.4%) than in the CA group (15.9%). The rate of procedural SAEs was significantly higher in the SA group (23%) than in the CA group (3.2%). The most common procedural SAEs in the SA group were pneumothorax (10%) and the need for pacemaker implantation (3.3%). The only procedural complications in the CA group were 1 case each of cardiac tamponade and stroke. During the 12 months of follow-up, the rates of SAEs were similar in the SA and CA groups (11.5% versus 12.6%, respectively). The most common SAEs during follow-up were pneumonia (3.2%) and AF-induced heart failure (3.2%) in the CA group and pneumonia (3.3%) and delayed hydrothorax (3.3%) in the SA group.
Surgical ablation of AF in patients who have had an unsuccessful prior CA procedure or who have an enlarged LA is more effective than radiofrequency CA but is associated with a higher risk of procedural SAEs.
This study is important because it is the first randomized comparison of surgical versus catheter ablation of AF. It is noteworthy that the study was performed in selected patients with AF, most commonly patients who already had already failed a CA procedure. Therefore the results should not be generalized to all patients with drug-refractory AF.
The results of AF ablation, whether performed with a catheter or surgically, are highly dependent on the ablation strategy that is employed. One of the probable reasons that SA had greater efficacy than CA in this study is that the surgical approach was more comprehensive than the catheter approach and consisted not only of pulmonary vein isolation and linear ablation, but also ablation of ganglionated plexi and excision of the left atrial appendage. On the other hand, the CA strategy was relatively minimalistic, consisting only of antral pulmonary vein isolation in approximately 50% of patients. Because the majority of patients in this study had failed a prior CA procedure, extra-pulmonary venous triggers may have been responsible for recurrent AF in some patients. Yet the CA strategy did not include any attempts to identify extra-pulmonary venous AF triggers, even among the patients with paroxysmal AF, who made up two-thirds of the study population. Furthermore, in the patients with persistent AF, complex atrial fractionated electrograms were not targeted. While antral pulmonary vein isolation with or without 1-2 ablation lines is a reasonable initial strategy for persistent AF, in patients who have failed a prior CA procedure, success is unlikely to be achieved without more extensive ablation outside the antral regions.
A limitation of the study is that the ablation strategy that was used at the 2 centers that participated in the study was different in the CA and SA arms. Because there was not a significant difference in efficacy between the 2 centers, this limitation probably did not affect the results of the study.
Another limitation has to do with the objective documentation of recurrent AF during follow-up. It is difficult to argue that the absence of AF on 7-day Holter monitor recordings during follow-up was a reliable indicator of freedom from AF when approximately one-half of the subjects had no AF on the baseline 7-day monitor.
Despite its limitations, this randomized study provides new data that could be helpful to clinicians for making evidence-based recommendations to patients with AF who have not responded adequately to antiarrhythmic drug therapy. The study highlights the possible advantage (greater efficacy) and disadvantage (greater risk) of SA compared to CA.
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