Catheter Ablation for Atrial Fibrillation
Abstract & Commentary
With Comment by John P. DiMarco, MD, PhD, Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville, Editorial Board, Clinical Cardiology Alert.
Synopsis: The data provide a picture of the evolving status of catheter ablation of atrial fibrillation in the period of 1995 through 2002.
Source: Cappato R, et al. Circulation. 2005;111:1100-1105.
In this study, Cappato and colleagues report the results of a survey on the current status of catheter ablation for atrial fibrillation. Cappato et al sent a detailed questionnaire about catheter ablation for atrial fibrillation to 777 electrophysiology laboratories throughout the world. Centers that agreed to participate, answered 43 questions on the history and current status of their program for ablation of atrial fibrillation. The questionnaire data were then used to assess the following outcome parameters: freedom from recurrent atrial fibrillation in the absence of antiarrhythmic drugs, freedom from recurrent atrial fibrillation in the presence of formerly ineffective antiarrhythmic drugs, overall freedom from recurrent atrial fibrillation, and the development of major complications.
One hundred eighty-one of the surveyed 777 EP laboratories responded to the questionnaire. Between 1995 and 2002, 100 (55.9%) of the 181 centers had started a program of catheter ablation for atrial fibrillation. These 100 centers reported data on 9370 patients who underwent 11,762 catheter ablation procedures. The centers had varying criteria for performing catheter ablation for atrial fibrillation and differing exclusion criteria.
Five different catheter ablation strategies were reported. These were right atrial compartmentalization (852 patients), left atrial compartmentalization (1080 patients), ablation of the triggering focus or foci (1526 patients), pulmonary vein electrical disconnection (6600 patients), and a combination of 2 or more strategies or unspecified strategies (631 patients). A second or third procedure was required in 2389 (25.4%) of the 9370 patients. There was a steady increase in the total number of catheter ablations of atrial fibrillation performed annually, with a gradual shift towards pulmonary vein disconnection and left atrial compartmentalization over other strategies seen over time.
For the entire group, 52% of patients became asymptomatic in the absence of antiarrhythmic drug, and another 23.9% of patients became asymptomatic with continued use of formerly ineffective antiarrhythmic drugs. To achieve this reported success rate, 24.3% required 2 procedures and 3.1% required 3 procedures. Therefore, 6644 (70.9%) patients received control of atrial fibrillation with or without drug therapy. It should be noted that the range for reported success rates between centers was very broad (22.3%-91%). There was a significant relationship between the number of procedures performed per center and the overall success rate.
There was no general agreement on the best pre-operative evaluation or adjunct intraoperative techniques. Most centers used some form of anticoagulation leading up to the procedure, and all centers used heparin during the procedure. After ablation, 83% of the centers reported using oral anticoagulants for some period of time. Aspirin was administered in the remaining 17% of centers.
A major complication was reported in 524 patients (6%). There were 4 reported periprocedural deaths (0.05%). The most common complications were tamponade (1.2%), femoral pseudoaneurysm (0.53%), and arteriovenous fistulae (0.42%). Among the 7154 patients who had left atrial procedures, stroke was noted in 20 (0.28%) and transient ischemic attacks in 47 (0.66%). Pulmonary vein stenosis was noted acutely or chronically in 1.63%.
In addition, atypical atrial flutter of new onset, which was presumed to be iatrogenic, was reported in 3.9% of patients. This complication was more frequently observed in centers using 3D guided compartmentalization strategies for left atrial ablation.
Cappato et al conclude that their data provide a picture of the evolving status of catheter ablation of atrial fibrillation in the period of 1995 through 2002. These data may serve as a guideline to clinicians considering referring patients for this procedure.
Comment
The data presented in this survey provide an interesting overview of the development of catheter ablation for atrial fibrillation throughout the world. Atrial fibrillation is the most common sustained arrhythmia, affecting over 2 million people in the United States alone. Unlike most other supraventricular arrhythmias, it has proved to be very resistant to catheter ablation approaches. Since 1995, efforts at catheter ablation of atrial fibrillation have been slowly progressing. The data in this survey show both the progression of the technique and the limitations of the procedures so far developed.
Since 2002, the techniques for catheter ablation of atrial fibrillation have continued to evolve. Catheter ablation is now commonly used in patients with more prolonged forms of atrial fibrillation and in patients with heart failure and left atrial distention. Outcome data on the new techniques, and in patients with more complicated histories, are quite limited. Long-term data greater than 5 years are, of course, unavailable. It has also been recognized that patients with atrial fibrillation will have asymptomatic episodes after a catheter ablation, so data that rely on symptomatic recurrences are overestimates of the success of the procedure. Therefore, there still remain questions about whether these patients can be followed off anticoagulants if they previously had indication for warfarin for stroke prevention.
Ablation of atrial fibrillation has been shown to be very useful in patients with frequent symptomatic episodes of paroxysmal atrial fibrillation. In selected patients, it may be the therapy of choice. Further, long-term data are needed, and safer techniques will be required, before catheter ablation can be considered primary therapy for the majority of patients with atrial fibrillation.
The data provide a picture of the evolving status of catheter ablation of atrial fibrillation in the period of 1995 through 2002.
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