Five-year Follow-up of Atrial Fibrillation Ablation
Abstract & Commentary
By John P. DiMarco, MD, PhD
Source: Weerasooriya R, et al. Catheter ablation for atrial fibrillation: Are results maintained at 5 years of follow-up? J Am Coll Cardiol. 2011;57:160-166.
Most prior study results of catheter ablation for atrial fibrillation (AF) have had relatively short follow-up duration. In this paper, the group from the Hospital Cardiologique du Haut-Leveque in Bordeaux, France, reports its experience in 100 patients who underwent catheter ablation between January 2001 and April 2002 who were respectively followed for at least 5 years to determine long-term outcomes. Patients were excluded if they had prior AF ablation attempt, resided outside of France, had a history of atrial fibrillation for less than 6 months, or had less than one hour per week of atrial fibrillation on average. The authors' ablation protocol has been previously described. In general, radiofrequency ablation was performed using a trans-septal approach and an irrigated tip ablation catheter. All segmental pulmonary vein ostia were systematically isolated, and a cavo-tricuspid isthmus ablation lesion was placed in every patient. Linear left atrial ablation and mitral isthmus ablation lesions were used selectively in patients with persistent or longstanding, persistent atrial fibrillation. Follow-up was performed at one, three, six, and twelve months after the initial procedure, and then at annual intervals. Follow-up testing included 24-hour Holter monitoring, transthoracic echocardiography, and exercise stress testing. Patients with symptoms were encouraged to seek electrocardiographic documentation during the episode. Patients with documented recurrence were offered repeat ablation. Patients who had documentation of atrial tachycardia or atrial flutter were considered ablation failures. Complete success was defined as the absence of symptoms or episodes of AF, atrial tachycardia, or atrial flutter of greater than > 30 seconds duration off antiarrhythmic agents.
The 100 patients in this report were selected from 552 patients who underwent catheter ablation at the author's institution during the entry period for this study. Most of the other patients were excluded because they had undergone a prior ablation (n = 256) or had inadequate histories of AF (132). The mean age in the study group was 56 years, and 86% were male. The types of atrial fibrillation were paroxysmal in 64%, persistent in 22%, and longstanding persistent in 14%. Only 36% had structural heart disease. The mean left ventricular ejection fraction was 70 + 11%. Hypertension was present in 43 patients. The CHADS2 score was 0 in 48 patients, 1 in 32 patients, and ≥ 2 in 20 patients. Patients had failed 3.5 + 1.4 prior antiarrhythmic drugs, and 67% had unsuccessful trials of amiodarone.
In the 100 patients reported here, a total of 175 procedures were performed, with a mean number of 2 per patient. Forty-nine patients had a single procedure, 34 had 2 procedures, 13 had 3, and four had between 4 and 7 catheter ablation attempts. Recurrent AF was the major indication for a repeat procedure (60%), but other atrial tachyarrhythmias were seen in 40%. Actuarial arrhythmia-free survival rates after a single catheter ablation procedure were 39.8 + 5.1%, 36.5 + 5%, and 28.5 + 4.7% at 1, 2, and 5 years, respectively. Recurrences were most frequent during the first six months. However, a late recurrence among patients who had maintained sinus rhythm for one year was observed in 28% of the patients. When all interventions were analyzed, the atrial arrhythmia-free survival rates following the last ablation procedure were 87.1% + 3.5%, 81.4 + 4.1% and 62.9 + 5.4% at 1, 2, and 5 years, respectively. The most common causes for recurrent arrhythmias were either recovery of pulmonary vein conduction or gaps in linear lesions, but non-pulmonary vein foci and left atrial flutter were also noted. By multivariate analysis, predictors of recurrence were found to include valvular heart disease and history of a nonischemic dilated cardiomyopathy.
The authors conclude that although the long-term success of a single ablation procedure for AF is modest, a catheter-ablation strategy with repeat interventions, as necessary, provides acceptable long-term results in a high proportion of patients. They argue that long-term follow-up data should be openly discussed with the patients and factored into clinical decision-making.
This paper provides important insights into the role of catheter ablation in the management of patients with AF. In patients with little or no associated heart disease, AF is primarily an electrophysiologic problem, and catheter ablation directed at the pulmonary veins, the most common source for AF, is likely to be successful. In these patients, the primary limitation to catheter ablation is the tendency for veins to reconnect. As underlying heart disease progresses, so does the atrial substrate, and catheter ablation becomes less successful. Now the appropriate comparison is not to an ablation procedure for Wolff-Parkinson-White syndrome, where ablation yields a life-long cure, but rather to coronary interventions, which lessen symptoms, but may need to be repeated over time. The authors recognize this, and I agree with their recommendation that true long-term results should be discussed with patients so that their expectations are in line with actual results. Catheter ablation for most patients with AF represents intermediate-term palliation that may be very beneficial, but a need for repeat procedures should be expected to maintain long-term arrhythmia control.