More is not better when it comes to catheter ablation to treat persistent atrial fibrillation. A randomized controlled clinical trial found additional ablation did not improve outcomes, a result that may prompt a revision in guidelines.
Atul Verma, MD, of Southlake Regional Health Centre in Newmarket, Ontario, and other researchers in the STAR AF II trial published their results May 7 in the New England Journal of Medicine. STAR AF II (Substrate and Trigger Ablation for Reduction of Atrial Fibrillation Trial Part II) evaluated three approaches for treating persistent atrial fibrillation using radiofrequency energy: ablation with pulmonary-vein isolation alone, pulmonary-vein isolation plus ablation of complex fractionated electrograms and pulmonary-vein isolation plus linear ablation.
“Data from randomized trials comparing methods of ablation for persistent atrial fibrillation are limited,” they observed. “Despite the paucity of data, guidelines suggest that 'operators should consider more extensive ablation based on linear lesions or complex fractionated electrograms for ablation of persistent atrial fibrillation.’”
They enrolled patients in 48 centers and 12 countries between 2010 and 2012, with 61 treated by isolation alone, 244 by isolation plus electrograms and 244 by isolation plus lines. They obtained clinical assessments, 12-lead electrocardiograms and 24-hour Holter-monitor recordings at three, six, nine, 12 and 18 months. Participants also were asked to transmit rhythm recordings weekly and when they experienced symptoms using a phone-based monitor for the 18-month follow-up period.
At 18-months follow-up, 59 percent of the patients who received isolation alone were free of recurrent atrial fibrillation vs. 49 percent for isolation plus electrograms and 46 percent for the isolation plus lines group.
They performed repeat ablations in 21 percent of the isolation alone patients, 26 percent of the isolation plus electrograms group and 33 percent for the isolation plus lines group. Freedom of atrial fibrillation rates were not significantly different among the groups.
“Our findings are not in accordance with the current guideline recommendation that patients with persistent atrial fibrillation who undergo pulmonary-vein isolation should have additional substrate ablation to improve outcome,” they wrote.
Pulmonary-vein isolation alone was successful in about half of patients, they noted, with a success rate about 60 percent after two procedures. Pulmonary-vein isolation alone also required less procedure time and fluoroscopy exposure.
The 1:4:4 randomization design left the study underpowered to determine if pulmonary-vein isolation alone was superior to the other two approaches, though. Verma et al recommended more research be done.
STAR AF II was funded by St. Jude Medical.