Ablation vs Drug Therapy for Intermittent Atrial Fibrillation
Abstract & Commentary
By John P. DiMarco, MD, PhD, Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville. Dr. DiMarco is a consultant for Novartis, and does research for Medtronic and Guidant.
Source: Pappone C, et al. A Randomized Trial of Circumferential Pulmonary Vein Ablation vs Antiarrhythmic Drug Therapy in Paroxysmal Atrial Fibrillation: The APAF Study. J Am Coll Cardiol. 2006; 48:2340-2347.
In this paper Pappone and his colleagues report a randomized study comparing circumferential pulmonary vein ablation (CPVA) to antiarrhythmic drug therapy in patients with paroxysmal atrial fibrillation who had previously failed at least one trial with antiarrhythmic drugs. Patients were eligible for entry into the study if they were between ages 18 and 70, and had experienced episodes of atrial fibrillation for more than 6 months with at least 2 episodes per month during that time period. Patients also were required to have developed recurrent arrhythmias during therapy with propafenone, disopyramide or quinidine, either as single agents or in combination with digoxin or verapamil. Patients were enrolled between January and May 2005 and were randomized to either CPVA or long-term antiarrhythmic therapy with either amiodarone, flecainide, or sotalol at maximally tolerated doses. CPVA was performed using the standard technique with either CARTO or NavX mapping systems. Either an 8 mm standard radiofrequency catheter or an irrigated tipped catheter was used for ablation. The pulmonary veins were isolated with mitral isthmus and cavotricuspid isthmus lines performed in all patients. Patients were treated with an antiarrhythmic drug for 6 weeks after catheter ablation and the trial's 12-month follow-up began at that point. Repeat procedures were permitted if there was a recurrence of either atrial fibrillation or atrial tachycardia beyond the first 6 weeks after the ablation. In the antiarrhythmic drug group, patients were begun on oral therapy with either flecainide, sotalol or amiodarone. There was a one-month run-in phase that allowed dosage adjustment. Combination therapy with 2 agents could be used in the case of failure of the first assigned drug. All patients were anticoagulated with warfarin but anticoagulation could be discontinued if sinus rhythm was maintained for greater than 6 weeks. During follow-up, all patients were seen in an outpatient clinic at 3, 6 and 12 months after randomization. At each visit, a 12-lead electrocardiogram, 48 hours of ambulatory electrocardiographic monitoring and a transthoracic echocardiogram were obtained. Patients also received an event recorder and were asked to record and transmit a rhythm strip one to 3 times daily routinely and whenever they experienced palpitations. Rhythm transmissions were available from all patients for 94% of the days during follow-up. The primary endpoint of the study was freedom from documented recurrent atrial tachyarrhythmia during the 12-month follow-up.
One-hundred-ninety-eight patients were randomized. The mean age was 56 years and 67% were male. The patients had experienced a mean of 6 AF episodes per month over a mean period of 6 years. A history of hypertension was seen in 56.5% and the mean left-ventricular ejection fraction was 60%. There were no significant clinical differences between the CPVA and the antiarrhythmic drug therapy group.
In the ablation group, patients received a mean of 35 minutes of radiofrequency energy delivery with a mean procedure time of 81 minutes. After the 6- week blanking period, 85 patients remained free of antiarrhythmic atrial tachyarrhythmias, and 11 patients developed atrial fibrillation, with 5 of these controlled by antiarrhythmic drugs, and 6 requiring a repeat ablation session. The repeat procedure was successful in 5 out of 6. Atrial tachycardias were observed in 3 additional patients, all of whom underwent successful repeat ablations. At 12 months, there was a decrease in left atrial size from 40 + 6 mm to 36 + 6 mm. Serious complications were uncommon. One patient developed a brief transient ischemic attack without sequelae, and one patient was noted to have a small pericardial effusion.
In the antiarrhythmic drug therapy group, 24 (25%) patients had their atrial fibrillation suppressed with a single antiarrhythmic drug. Combination therapy with either flecainide plus sotalol or flecainide plus amiodarone was successful in 33 of 75 patients, and the remaining 42 patients crossed over to CPVA. Adverse drug effects were noted in 23 patients. Three patients on flecainide developed proarrhythmia, 7 patients on amiodarone developed thyroid dysfunction, and sexual dysfunction was noted in 11 patients on sotalol.
Kaplan-Meier analysis of arrhythmia recurrence was performed using the end of the 6-week blanking period as time 0. Eighty-six percent of patients randomized to CPV were free of atrial arrhythmias at the end of follow-up as compared to only 22% of the antiarrhythmic drug therapy patients.
The authors conclude that among patients with a long history of paroxysmal atrial fibrillation and a previous failure of an antiarrhythmic drug, a single CPVA is more effective than antiarrhythmic drug therapy with alternate agents.
Commentary
Indications for catheter ablation to treat atrial fibrillation remain controversial. In this study, Pappone and his colleagues from Italy confirm their previous excellent results with CPVA and show that an ablation based approach results in less atrial fibrillation than antiarrhythmic drug therapy. Before catheter ablation can be routinely recommended, several points should be considered. First, these patients were really ideal candidates for catheter ablation. They were relatively young, had few comorbidities, had normal or nearly normal left atrial size and a long history of frequent episodes of atrial fibrillation. Second, they had already failed an antiarrhythmic drug. Since patients tend to segregate into drug responders and nonresponders, one would have expected a relatively high rate of recurrence on therapy with an alternate agent. Third, the techniques for catheter ablation of atrial fibrillation are still evolving. The results reported by these investigators from Italy have consistently been among the best, and many other laboratories have not been able to duplicate such high efficacy and low complication rates. When recommending catheter ablation, cardiologists must consider the results in the laboratory that will perform the procedure. Finally, the most important measure of the effectiveness of antiarrhythmic therapy for atrial fibrillation is the effect on symptoms. Although one might infer from the results reported here that symptoms were improved in the ablation group, inclusion of a formal quality-of-life measure or some other objective measure of symptom burden would help us to define better the benefit of catheter ablation relative to drug therapy.
In this paper Pappone and his colleagues report a randomized study comparing circumferential pulmonary vein ablation (CPVA) to antiarrhythmic drug therapy in patients with paroxysmal atrial fibrillation who had previously failed at least one trial with antiarrhythmic drugs.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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