Cleveland, OH - Pulmonary vein isolation with radiofrequency ablation is associated with better clinical outcomes than drug therapy and appears to be feasible as a front-line approach for the treatment of symptomatic atrial fibrillation (AF). In one of the first studies comparing catheter-based ablation of AF with standard antiarrhythmic drug therapy, investigators showed that pulmonary vein isolation was associated with less AF recurrence, improved quality of life, and a lower hospitalization rate at one year [1].

In this multicenter, prospective, randomized pilot study, led by Dr Oussama Wazni (Cleveland Clinic, OH) and published in the June 1, 2005 issue of the Journal of the American Medical Association, investigators directly compared catheter-based ablation of AF with standard antiarrhythmic drug therapy. Typically, pulmonary vein isolation, although shown in preliminary reports to eliminate AF completely, is considered only after drug therapy has failed, because of the risks associated with the procedure, such as stroke and pulmonary vein stenosis.

We are moving forward with performing the procedure more regularly, performing it as a standard of care that can benefit the many patients with AF.

"The standard of care for the treatment of atrial fibrillation has been to first consider drug therapy, either to maintain sinus rhythm or to achieve rate control," senior investigator Dr Andrea Natale (Cleveland Clinic) told heartwire. "The problem with these approaches is that they are not very effective. Even in the best-case scenario, over four or five years atrial fibrillation is under control in maybe 30% or 40% of patients. Catheter ablation of atrial fibrillation really then becomes one of the few options that we have to cure it. The therapy has evolved over the past five or six years, to a point where we are able to cure a significant number of patients of their atrial fibrillation. With one or two ablation procedures, we have been able to eliminate their atrial fibrillation completely."

Patients were included in the study if they experienced monthly symptomatic AF episodes for at least three months and had not previously been treated with antiarrhythmic drugs. There were no differences in baseline patient characteristics, including age, left atrial size, and duration and type of AF, among those randomized to ablation (n=32) and those randomized to drug therapy (n=35). The primary end point of the study was any recurrence of symptomatic AF or asymptomatic AF lasting longer than 15 seconds during Holter or event monitoring in the one-year follow-up period.

In the drug group, the physician providing patient care chose the drug; it was recommended that the maximum tolerable dose of each agent be used. The recommended medical regimen consisted of oral flecainide (100-150 mg) twice daily, propafenone (225-300 mg) three times daily, or sotalol (120-160 mg) twice daily. The end point of ablation was complete electrical disconnection of the pulmonary vein antrum from the left atrium.

After excluding events in the first two months after enrollment, 22 patients in the drug group compared with four patients in the ablation group had at least one AF. Of these events, asymptomatic AF was documented in 16% of the drug group and in 2% of the ablation group. Asymptomatic mild or moderate pulmonary vein stenosis developed in two patients randomized to ablation.

At six months, improvements in quality of life of patients in the ablation arm were also significantly better than improvements in drug group (as measured by the Short-Form 36 health survey).

"This is a preliminary study and a preliminary result, but the findings are encouraging," said Natale. "The next step will involve repeating the study in more centers, which have begun, mostly in North America and a few European centers. This study will include less-specialized, lower-volume centers so that we can prove that what we achieved at these highly experienced hospitals can be the standard of care for everybody else."

Natale and colleagues point out that the technique for performing pulmonary vein isolation is similar but not identical to other catheter-based techniques for performing AF ablation. Although the best technique for AF ablation remains a debated topic, they write that ablation techniques continue to evolve as knowledge, experience, and technology advance. Although the pilot study proved that catheter-based ablation of AF is feasible, Natale told heartwire that the procedure still requires experienced operators.

"This is an extremely complex procedure that has the potential for serious complications," he said. "But there are a large number of physicians being trained in the ablation procedure and in the next few years we are bound to see an increase in the number of electrophysiologists capable of doing a good job. At this point, I would not encourage clinicians with no experience to do the procedure, but this study is certainly a start. We are moving forward with performing the procedure more regularly, performing it as a standard of care that can benefit the many patients with atrial fibrillation."