Abstract & Commentary
Synopsis: The described technique for pulmonary vein ablation yields results superior to medical therapy in a broad spectrum of patients with atrial fibrillation.
Source: Pappone C, et al. J Am Coll Cardiol. 2003;42:185-197.
Pappone and colleagues present an observational study evaluating the efficacy of their laboratory’s technique for pulmonary vein isolation. The approach used by Pappone et al involves circumferential isolation of the pulmonary vein ostia using an electroanatomic approach. This technique places a ring of lesions at least 5 mm from the ostia themselves. Pappone et al report on 1171 consecutive patients with paroxysmal or chronic atrial fibrillation referred to their laboratory for evaluation. Of these, 589 patients underwent pulmonary vein isolation and 582 received medical therapy. Therapy was selected by Pappone et al and was not randomly assigned. The entire group had a mean age of 65, and 59% were male. About 35% had no structural heart disease, and 44% had only hypertension. The mean left ventricular ejection fraction was 54%, and the mean left atrial diameter was 4.5 cm. The ablation group was then compared to the medical therapy group in terms of the following parameters: total mortality, nonfatal adverse cardiac events, atrial fibrillation recurrence, left atrial size change, hospitalization, and quality of life. The median follow-up was 900 days for both groups.
There were 38 (6%) deaths in the ablation group vs 83 (14%) deaths in the medical therapy group. Observed survival probabilities were 98%, 95%, and 92% at 1, 2, and 3 years, respectively, in the former group, and 96%, 90%, and 86% in the latter group. Survival in the ablation group matched expected survival for an age-matched Italian population. Survival was poorer than expected in the medical therapy group. Heart failure and ischemic strokes or transient ischemic attacks were more common in the medical group. In both groups, these adverse effects were usually associated with recurrent atrial fibrillation (72%) and/or inadequate anticoagulation (50%). Ablation was associated with improved rhythm control with 120/589 (20%) ablation patients compared to 340/582 (58%) medical therapy patients experiencing 1 or more recurrences of atrial fibrillation. The majority of the ablation patients who developed recurrent atrial fibrillation did so during the first year after their procedure. An enlarged (> 4.5 cm) left atrium and a smaller area encircled by the ablation lesions were predictors of recurrence. There was also a fourfold reduction in left atrial size and an increase in peak A-wave velocity in the ablation group. Finally, the ablation group, but not the medical group, reported an improvement in quality of life. Medical therapy patients reported no change in quality of life during the course of the study.
Pappone et al conclude that their technique for pulmonary vein ablation yields results superior to medical therapy in a broad spectrum of patients with atrial fibrillation.
Comment by John DiMarco, MD, PhD
Since the initial description of focal sources of atrial fibrillation arising from the pulmonary veins, there has been intense interest in catheter ablation as a potential cure for atrial fibrillation. As yet, there has not evolved a standard approach for either selecting patients or actually performing the procedure.
Pappone et al present the first truly large series of patients who have undergone pulmonary vein ablation. The group was predominantly middle-aged, and many patients had a history of hypertension, the most common etiology of atrial fibrillation in this age group. Although there were relatively few patients with severe left ventricular dysfunction, this patient group is more representative of the average atrial fibrillation patient than has been reported in other ablation series, which often had a large proportion of young patients with no heart disease. In these patients, Pappone et al report excellent success rates and virtually no acute or long-term complications.
The technique used by Pappone et al is somewhat different from that used in most laboratories. The ablation lesions are placed anatomically in rings around the pulmonary vein ostia. These large rings also include a portion of the posterior left atrial wall, and this may contribute to the high efficacy rate reported here. Since detailed mapping is not performed, less instrumentation is required and the procedure duration is comparatively short.
The major limitation of this paper is that the assignment of ablation or medical therapy was not randomized. Most patients in both groups had previously had recurrences while on drugs, so recurrent arrhythmias should not have been unexpected. Amiodarone, the most effective antiarrhythmic drug, was used in only 33% of the medical therapy patients. Factors not included or completely accounted for by the Cox proportional hazards model likely affected outcomes. The data here do not imply that ablation should be first-line therapy. Rather, they imply that ablation is an evolving strategy that provides an alternative to drug therapy for an expanding pool of patients.
Dr. DiMarco, Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville, is on the Editorial Board of Clinical Cardiology Alert.