ACC.15: Ablation with mitral valve surgery proves safe, effective

SAN DIEGO—Performing an ablation along with mitral valve surgery is more likely to keep cardiac patients free of persistent atrial fibrillation (AF) at one year, according to results unveiled March 16 at the American College of Cardiology scientific session. But it also increased the risk of needing a pacemaker.

A. Marc Gillinov, MD, of the Cleveland Clinic, presented the study on behalf of the Cardiothoracic Surgical Trials Research Network  team. They designed the trial to evaluate the safety and effectiveness of surgical ablation in patients with persistent or long-standing persistent AF who were undergoing mitral valve surgery. They included two ablation approaches—pulmonary vein isolation and the more complex biatrial maze procedure—in order to compare the two.

“If we go to the guidelines and ask this question [how to treat this type of patient] we get the answer: An AF surgical ablation is reasonable for selected patients with AF who are undergoing cardiac surgery for other indications,” he said. “This is a class 2A recommendation but the level of evidence is only a C. This is the background for the current trial.”

The 20 participating U.S. and Canadian hospitals randomized half of the 260 patients undergoing mitral valve surgery with AF to concurrently receive ablation and half to mitral valve surgery alone as the control. The ablation group was further randomized to treatment by pulmonary vein isolation or the biatrial maze procedure. Their primary endpoint was freedom from AF at six and 12 months, based on three-day Holter monitoring.

Twenty percent of participants lacked primary endpoint data and consequently their outcomes were imputed. “Operative characteristics were similar between the groups except that patients undergoing ablation had about a 15-minute longer period on cardiopulmonary bypass, so the addition of ablation took about 15 extra minutes operative time,” he noted.

At six and 12 months, nearly twice as many patients in the ablation group remained free of AF as the control (63.2 percent vs. 29.4 percent). At 12 months, 45.2 percent of control patients had daily episodes of atrial fibrillation as opposed to 19.8 percent of those who received ablation. There was no difference in outcomes between the two ablation techniques.

One-year mortality among ablation patients was 6.8 percent and in those in the control it was 8.7 percent. Rates for major adverse cardiac or cerebrovascular events also were similar. Patients in the ablation group were more than twice as likely to require implantation of a permanent pacemaker, most often during their index hospitalization.

Gillinov described the Holter monitor as a stringent endpoint but panelist Eric C. Bates, MD, of the University of Michigan Health System in Ann Arbor, questioned if the electrophysiology community would accept two three-day monitoring periods as a good measure of therapeutic effectiveness. He also said the high success rate was a surprise.

Gillinov pointed to Heart Rhythm Society guidelines, which support the use of three-day Holter monitoring as an endpoint. “Actually, single-center studies in certain literature report success rates of 80 percent and sometimes even 90 percent,” he replied. “What I am getting at is, the more you look for afib the more you find, so I suspect our 63 percent success rate represents looking harder.”

Richard Fogel, MD, an electrophysiologist at the Care Group and CEO of St. Vincent Medical Group in Indianapolis, asked if, based on the results, Gillinov would consider a biatrial maze procedure for every patient with persistent AF who was to undergo mitral valve surgery. Gillinov said in most cases, yes, but not in a scenario involving a very sick patient and a complex, long operation. “In some rare instances, even 15 extra minutes of operating time might be too much. But this says the default operation is treat the atrial fibrillation.”

The study was published concurrently in the New England Journal of Medicine.

Angela Marshall contributed to this article.