ACC: Ablation bests a-fib drugs in pilot study--onto bigger CABANAs
ATLANTA--Ablative intervention was more effective than drug therapy for preventing recurrent symptomatic atrial fibrillation, according to the CABANA trial results presented Monday during a late-breaking clinical trial session at the American College of Cardiology’s (ACC) 59th annual conference.

The Catheter Ablation Versus Anti-arrhythmic Drug Therapy for Atrial Fibrillation (CABANA) pilot study—one of the first to evaluate the feasibility of catheter ablation in patients with more advanced atrial fibrillation (AF) and substantial underlying cardiovascular disease—was designed to lay the foundation for a large, randomized controlled trial.

“This pilot study establishes the feasibility and importance of conducting an extended pivotal trial critical for establishing long-term outcomes, mortality, quality of life and cost of ablation and drug therapy for atrial fibrillation,” said principal investigator Douglas L. Packer, MD, a cardiologist at Mayo Clinic in Rochester, Minn.

For the study, investigators recruited 60 patients with AF, more than two-thirds of whom had a persistent or long-standing persistent form of the arrhythmia. The study group tended to have multiple additional health problems: 80 percent of patients had high blood pressure, 18 percent had diabetes, 35 percent had coronary artery disease and 36 percent had mild-to-moderate heart failure. Also, forty-eight percent already had left atrial enlargement. Some 30 percent of patients had previously tried anti-arrhythmic drug therapy.

Of the 60 patients in the study, 31 were randomly assigned to drug therapy, and were treated with either anti-arrhythmic drugs (87 percent) or medications to only control the heart rate without eliminating the arrhythmia (13 percent). The remaining 29 patients were randomly assigned to catheter ablation.

In nearly all patients, radiofrequency energy was applied to tissue around the entrance of the pulmonary veins, according to Packer. In addition, in 45 percent, electrophysiologists chose to create additional linear lesions to block the spread of electrical impulses in problem areas.

Packer acknowledged the limitations of the trial, including the limited number of subjects and the limited follow-up of 12 months. “As expected, a small number of patients crossed over from drug to ablative therapy,” said Packer, adding that the small number of at-risk patients at 12 months limited the “late conclusions” that can be drawn.

Investigators found that catheter ablation was more effective than drug therapy for preventing recurrent symptomatic AF. However, treatment success rates in these patients, some of whom had persistent and long-standing persistent AF, were lower than observed in other randomized clinical trials. Late recurrent AF also may diminish the overall effectiveness of ablation therapy, according to Packer.

In his response to the study, incoming ACC president Ralph Brindis, MD, from Kaiser Permanente, said: “Due to the growing predominance of atrial fibrillation, this trial could be tremendously important in informing us how to manage this burgeoning population.”

Packer added: “We think this pilot indicates a signal, and even a mandate, for a longer term study.”

The CABANA pivotal trial, which is funded by NIH and industry, is currently recruiting patients at about 180 centers globally to further study this issue. The researchers are aiming for a total enrollment of 3,000.

The CABANA Pilot study was funded by St. Jude Medical Foundation.