Circumferential Pulmonary Vein Ablation Demonstrates Potential to Cure AF: Results of the APAF Trial

March 31, 2006

March 31, 2006 -- Circumferential pulmonary vein ablation (CPVA) therapy is more effective than antiarrhythmic drugs for the treatment of paroxysmal atrial fibrillation (AF), and may be able to cure a substantial number of AF patients, according to initial results of the Ablation for Paroxysmal Atrial Fibrillation (APAF) trial.

The controlled, randomized trial was presented this month at the American College of Cardiology 55th Annual Scientific Session in Atlanta, Georgia by Carlo Pappone, MD, PhD and his team at San Raffaele University Hospital in Milan, Italy. [1] The APAF results come less than 2 weeks after a small (145 patients) randomized study by Prof. Pappone's group was published in The New England Journal of Medicine[2] suggesting that CPVA was superior to antiarrhythmic drug therapy in patients with chronic AF. In his ACC presentation, Prof. Pappone said the APAF trial was designed to meet the need for a higher-powered, randomized, controlled study to better define the optimal treatment strategy for AF. The results, he said, suggest that ablation therapy may provide a cure for AF. However, in order to match the results observed in the trial, the procedure should be performed at high-volume, tertiary arrhythmia centers by physicians with a great deal of experience with CPVA.

As noted by Prof. Pappone, the APAF trial was designed with a 90% power to detect a 50% reduction in the incidence of recurrent AF at 1 year in patients treated with CPVA vs antiarrhythmic medical therapy (n = 85 in each group). He and his colleagues randomized 198 patients who had a history of paroxysmal, medication-resistant AF for at least 6 months and an AF burden of 2 episodes per month to either ablation therapy or treatment with 1 of 3 antiarrhythmic drugs (flecainide, sotalol, or amiodarone). The mean duration of AF at baseline was approximately 6 years, and patients in the CPVA group had a significantly higher incidence of AF episodes per year than in the control group (52 vs 30, P = .05).

Patients in the ablation group underwent CPVA performed on all 4 pulmonary veins using either a standard 8-mm catheter or a 3.5-mm irrigated tip catheter guided by either the CARTO (Biosense Webster) or NavX (St. Jude Medical) 3-dimensional mapping systems. Three additional ablation lines also were placed to prevent atrial tachycardia. Patients were then monitored using daily transtelephonic transmissions, plus 48-hour Holter monitoring and transthoracic echocardiography, performed at 3, 6, and 12 months. The primary endpoint was freedom from recurrent atrial arrhythmias, including AF, atrial tachycardia, and atrial flutter.

At the ACC, Prof. Pappone presented the results from the first 150 patients enrolled in the study who had reached at least 9 months of follow-up. A total of 87% of the ablation group was free from AF recurrence at 9 months, compared with 29% of the drug-treatment group ( P < .001). None of the patients in the ablation group who achieved persistent sinus rhythm required antiarrhythmic drugs, and all but 1 were able to discontinue their anticoagulant medication, he reported. Eight of the CPVA patients had AF recurrences and were treated with either drugs (n = 5) or a re-ablation procedure (n = 3). In the control group, 52 patients had AF recurrences, 38 of whom were treated with CPVA. Of the control patients treated with CPVA, 32 patients were in sinus rhythm at follow-up.

Of importance, Prof. Pappone noted, there was a significant decrease in left atrial diameter from baseline in patients who underwent ablation therapy, suggesting positive left atrial remodeling in these patients. Adverse events were rare in the ablation group and included only 1 transient ischemic event and 1 pericardial effusion. By contrast, the drug group experienced a number of adverse events, including 2 cases of significant proarrhythmia and 11 cases of sexual dysfunction.

Prof. Pappone told meeting attendees that when comparing the 2 mapping systems, "both were effective and safe to perform the procedure." However, when comparing the 2 ablation catheters, Prof. Pappone reported that the irrigated-tip catheter performed much better for the prevention of thromboembolic events and was able to produce more transmural lesions than the standard 8-mm catheter. In addition, among the antiarrhythmic drugs employed in the trial, amiodarone was more effective than either flecainide or sotalol.

The overall results, he concluded, demonstrate that CPVA is superior to antiarrhythmic drug therapy for the treatment of paroxysmal AF.

At a media briefing held during the ACC, Prof. Pappone stressed the importance of the findings, stating that "the results show that it is possible today to cure AF and maintain sinus rhythm in about 90% of patients." This can be achieved using CVPA without the need for long-term antiarrhythmic and anticoagulant drug therapy, he said.

References
  1. Pappone C, Augello G, Sala S, et al. A controlled randomized trial of circumferential pulmonary vein ablation versus antiarrhythmic drug therapy for curing paroxysmal atrial fibrillation. The Ablation for Paroxysmal Atrial Fibrillation (APAF) trial. Program and abstracts from the American College of Cardiology 55th Annual Scientific Session; March 11-14, 2006, Atlanta, Georgia. Abstract 302-6.

  2. Oral H, Pappone C, Chugh A, et al. Circumferential pulmonary-vein ablation for chronic atrial fibrillation. N Engl J Med. 2006;354:1934-1941.

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