Medscape CRM News 2006. © 2006 Medscape
"We now have proof that in [paroxysmal AF] patients in whom at least one drug has failed to control their AF, ablation performs much better than trying additional drugs. This holds true even for the most powerful antiarrhythmic drug, amiodarone" -- Pierre Jais, MD (Hôpital Cardiologique Haut-Leveque Bordeaux-Pessac, France)
In patients with symptomatic, paroxysmal atrial fibrillation (AF) who have already failed at least 1 attempt at antiarrhythmic drug (AAD) therapy, catheter ablation may be a better treatment choice than switching to another drug, according to the results of the Atrial Fibrillation vs Antiarrhythmic Drugs (A4)[1] trial.
A4 Investigators reported that compared with patients who were randomized to AADs, patients who received ablation therapy were much less likely to experience an episode of AF over a 12-month follow-up period and also demonstrated better exercise capacity and quality-of-life scores.
The results add to the positive evidence from other recent studies of AF catheter ablation, including 2 trials released earlier this year from Carlo Pappone, MD, PhD and colleagues (San Raffaele University Hospital, Milan, Italy), demonstrating the superiority of ablation vs AADs for maintaining normal sinus rhythm in patients with both paroxysmal and chronic AF (see Related Links).[2,3]
Pierre Jais, MD, of Hôpital Cardiologique Haut-Leveque (Bordeaux-Pessac, France), who presented the results of A4 at Heart Rhythm Society (HRS) 2006 Annual Scientific Sessions, said the results were crystal clear. "We now have proof that in [paroxysmal AF] patients in whom at least one drug has failed to control their AF, ablation performs much better than trying additional drugs. This holds true even for the most powerful antiarrhythmic drug, amiodarone," he asserted.
A4: Study Design and Methods
A4, which was conducted at 4 centers in Europe and North America, randomized 112 patients to receive either AAD therapy (n = 59) or ablation (n = 53). Patients had to have symptomatic, paroxysmal AF of at least 6 months' duration with at least 2 AF episodes per month, and resistance to at least 1 Class I or III AAD. The average age of the participants was 51 years, and 85% were male; the mean duration of AF episodes at baseline was 9 ± 9 hours; and 80% of patients were on anticoagulant drugs.
Patients were followed at 2, 3, 6, and 12 months using 24-hour Holter monitoring as well as patient-kept diaries. The primary endpoint, recurrence of AF, was defined as any episode of arrhythmia beyond Month 3 (documented or not) lasting more than 3 minutes. Secondary endpoints included quality-of-life scores, withdrawal of anticoagulation at 1 year, and adverse events/mortality.
The first 3 months of the trial were designated as a "blanking period" during which patients in the drug group were allowed to receive up to 3 different AADs, either alone or in combination, and those in the ablation group were allowed up to 3 ablation procedures. Repeat ablations were common, with a mean of 1.8 ablations performed per patient in this group. Circumferential pulmonary vein isolation was performed in all ablation patients, with additional focal or linear ablation lines placed as needed.
After 3 months, the patients were assessed for the primary and secondary endpoints and crossover was permitted if needed. Crossovers were common in the AAD group, with a total of 37 AAD patients who failed drug therapy crossing over to the ablation group by study end.
In his presentation, Dr. Jais conceded that the definition they used for AF recurrence was very strict and probably resulted in an overestimation of the number of treatment failures in the study. However, he explained that because of the lack of published data on the success rate of AADs in paroxysmal AF patients, the investigators had to define their own criteria for success and failure and thus decided to embrace a strict definition.
Results
The results are summarized in the table below. At 1-year follow-up, 75% of the ablation group was free of arrhythmia recurrence, compared with only 7% of the AAD group. Moreover, 60% of the ablation patients were able to discontinue oral anticoagulation therapy, compared with 25% in the AAD group who did not cross over. The Kaplan-Meier plots for time to AF recurrence also showed a highly statistically significant superiority of ablation over AADs (P < .0001). Patients who were treated with amiodarone for the first time during the trial achieved a slightly better result than the overall outcomes in the AAD group, with 21% of the first-time amiodarone patients being free from AF recurrence at 12 months. However, this was still far inferior to what was achieved in the ablation group.
The majority of the quality-of-life results also were significantly better in the ablation group, and these findings were maintained over the 12-month follow-up period. In addition, a 12-month stress test showed significantly greater improvement in the ablation group in several measures of functionality, including exercise duration and maximum systolic blood pressure.
Complications in the ablation group included 2 tamponades (including 1 reported in a crossover patient), 2 groin hematomas, and 1 pulmonary vein stenosis, while AAD complications included 1 patient with hyperthyroidism and 1 death due to cancer, which was probably not related to the AAD. No stroke or transient ischemic attacks were observed in either group over the 12-month follow-up.
The researchers concluded that in patients who have failed at least 1 AAD, AF ablation results in a far better outcome compared with those seen with other AADs. They called for further study to compare the impact of both strategies on a longer-term outcome.
Table. A4: Primary and Secondary Endpoints at 12 Months
Outcome Ablation Group
(n = 53) AAD Group
(n = 59) P
Free of arrhythmia recurrence at 1 year (%) 75 7 --
Discontinued oral anticoagulation (%) 60 25* --
Quality-of-life measures (intention-to-treat basis):
Physical function 91.3 82.2 .0012
Social function 90.4 80.9 .0024
Mental health 90.7 80.6 .0018
Physical component 52.0 48.9 .0174
Mental component 56.6 51.9 .0106
*Of the 22 patients who did not cross over to ablation group
Discussion, Limitations, and Future Technology
Following the presentation, session moderator A. John Camm, MD (St. George's Hospital Medical School, London, United Kingdom), questioned the study's design and asked whether such a soft endpoint that included palpitations of only 3 minutes' duration should be considered a true endpoint. He noted that it would be helpful if the trial were continued to collect more hard-endpoint data. Responding to the comments, Dr. Jais acknowledged that the study had limitations, but said the investigators had determined that continuation of the trial was not realistic because patients who fail drug therapy may want to have an ablation procedure and "they will not accept a trial where they cannot cross over."
Dr. Jais stressed the importance of proper patient selection for AF ablation, pointing out that ablation therapy can only be justified in symptomatic patients with a significant AF burden. "It probably doesn't make sense to offer ablation therapy for patients who have only 2 AF episodes per year," he said. "Ablation is not 100% safe. . . you have to keep in mind that you do have complications with this procedure." On the other hand, the trial clearly suggests that "if a patient fails one AAD, it doesn't make sense to try all the other available drugs because the chance of success is very low," he pointed out. In this case, he concluded, "physicians should consider going on to perform ablation, providing the patient has a minimal degree of AF."
AF ablation was a topic of great interest at this year's HRS meeting, which kicked off on Wednesday, May 17th, with a live, satellite-linked, transatlantic AF ablation case performed by Dr. Pappone that wowed attendees. Working from a lab in Boston, Massachusetts, Dr. Pappone used remote magnetic navigation technology and robotic controls to perform catheter-based, circumferential pulmonary vein ablation on a patient located in Milan, Italy. Marking the first public demonstration of such a feat, the procedure was successfully completed in about 1 hour in front of hundreds of rapt observers. Despite significant cost concerns, some contend that the use of the remote robotic technology can be used to educate other electrophysiologists on procedural techniques at different centers worldwide, and that the use of this technology may offer better clinical outcomes than those obtained using manual navigation.
Supported by an independent educational grant from St. Jude Medical.
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