Pulmonary vein antrum isolation may be superior to atrioventricular node ablation with biventricular pacing for treatment of drug-resistant atrial fibrillation in patients with heart failure, according to a late-breaking clinical trial presented at the American Heart Association meeting.

The Pulmonary Vein Antrum Isolation versus AV Node Ablation with Bi-Ventricular Pacing for Treatment of Atrial Fibrillation in Patients with Congestive Heart Failure, or PABA CHF trial, was the first head-to-head trial of procedures with a six-month follow-up.

Researchers randomized 71 patients with drug-resistant atrial fibrillation in five countries to receive pulmonary vein antrum isolation or AV node ablation with bi-ventricular pacing; 35 underwent vein isolation and 36 underwent AV node ablation.
After an ablation procedure, the patient is left dependent on an implantable cardioverter defibrillator or pacemaker. Although the technique has been used clinically for about 25 years, the addition of bi-ventricular pacing has become common only in the last three years in patients with heart failure.

During a pulmonary vein antrum isolation procedure, catheters inserted into the heart atria deliver radiofrequency energy to the pulmonary vein, creating a line of scar tissue that blocks electrical impulses, effectively disconnecting the pathway of the abnormal rhythm. The procedure requires puncturing the heart and crossing over into the left atrium. It has been performed and refined almost exclusively at large academic medical centers during the last 10 years.

In the study, patients could continue on anti-arrhythmic drugs and patients receiving the pulmonary vein isolation procedure could have a second after two months based on physicians’ judgment.

“As both heart failure and atrial fibrillation are becoming epidemics with the aging of the baby boom generation, pulmonary vein isolation may offer an option to address the confluence of these two problems in patients,” said Andrea Natale, MD, head of the section of electrophysiology and pacing at the Cleveland Clinic in Ohio.

At six months after the initial procedure, patients who underwent pulmonary vein isolation showed improvements on all primary endpoints compared with ablation patients: quality of life scores as measured by a questionnaire about daily activity limitations (61 vs. 79); six-minute walk distances (345 meters vs. 301 meters); and a higher ejection fraction (35 percent vs. 29 percent). The ejection fraction for the ablation group was close to the baseline ejection fraction for all patients in the study.

The results on the secondary endpoint, termination of atrial fibrillation, were even more compelling: 89 percent of isolation patients were free of atrial fibrillation, including 74 percent who were free of atrial fibrillation and not taking antiarrhythmic medication. None of the ablation patients were considered free of the arrhythmia.

Researchers also did a subanalysis of patients by atrial fibrillation category: paroxysmal/intermittent fibrillation, persistent fibrillation (constant fibrillation that could be converted to regular rhythm by the implantable cardioverter defibrillator, or permanent atrial fibrillation (constant arrhythmia resisting shock conversion to a regular rhythm).

They found that 42 percent of ablation patients experienced worsening arrhythmia severity compared with no worsening in isolation patients. In fact, 94 percent of isolation patients moved to a better category, including the high number of patients with and without anti-arrhythmic medication who had no atrial fibrillation at all. In comparison, only 6 percent of ablation patients moved to a better category.

Both procedures carry the risk of infection and perforation, while pulmonary vein isolation carries the further risk of stroke and pulmonary vein stenosis, Natale said. However, the only complication seen in the current trial was mild, symptomless pulmonary vein stenosis.

“pulmonary vein isolation leads to improvements in quality of life, functional capacity and ejection fraction versus ablation in patients with symptomatic atrial fibrillation with heart failure,” Natale said. “At specialized academic centers, patients who have symptomatic atrial fibrillation should be considered for isolation first before ablation.”