Ablation During Mitral Valve Surgery Reduces Atrial Fibrillation in Trial

March 16, 2015—Patients with atrial fibrillation who underwent ablation while they were already undergoing surgery to correct heart valve leakage had fewer episodes of atrial fibrillation 1 year after the procedure compared to patients who had the valve surgery alone, according to a study presented at the 64th annual scientific session of the American College of Cardiology (ACC). The study was simultaneously published online in The New England Journal of Medicine.

The study also showed that the patients who underwent ablation along with mitral valve surgery had no more deaths, adverse cardiac events, or hospitalizations than patients who only underwent the valve surgery alone; however, they were more likely to require a pacemaker.

In a press release, the ACC advised that the study included 260 patients within the Cardiothoracic Surgical Trials Network, a clinical research network involving 20 hospitals in the United States and Canada. The US National Institutes of Health and Canadian Institutes for Health Research supported the design and conduct of the trial.

This is the first appropriately powered randomized clinical trial to assess the use of ablation in patients already undergoing mitral valve surgery, stated the ACC.

As summarized by the ACC, the study randomized patients (1:1) to undergo mitral valve surgery alone or surgery with surgical ablation. All of the study participants had persistent or long-standing persistent atrial fibrillation and were undergoing surgery to repair or replace the mitral valve.

Of the patients who underwent ablation and mitral valve surgery, 63% were free from atrial fibrillation at 6 and 12 months after surgery. By contrast, 29% of patients who underwent mitral valve surgery alone were free from atrial fibrillation at those time points.

Surgeons have begun combining the two procedures to address both cardiac issues at the same time because many patients in need of valve repair also have atrial fibrillation, although the two conditions are not related.

Marc Gillinov, MD, the Judith Dion Pyle Chair in Heart Valve Research at the Cleveland Clinic in Cleveland, Ohio, is the study’s Lead Investigator. Dr. Gillinov commented in the ACC press release, “Although surgeons are widely performing ablation at the time of mitral valve surgery, there is a great deal of variation with regard to when it is done, how it is done, and which patients receive it. We sought to conduct a well-designed randomized controlled trial to answer fundamental questions about whether this procedure is successful and how it is best done.”

Dr. Gillinov noted that in the absence of strong clinical guidance regarding the use of ablation with mitral valve surgery, the decision is left largely up to physician preference. Approximately two-thirds of surgeons currently perform ablation during mitral valve surgery for patients with persistent atrial fibrillation, and one-third of surgeons do not.

The patients who underwent ablation were significantly more likely to be free of atrial fibrillation at 6 and 12 months after surgery, but the study showed no significant differences in rates of death, adverse cardiac events, or hospitalization. Patients who underwent mitral valve surgery alone reported a slightly lower quality of life because more of these patients said they still experienced daily atrial fibrillation 1 year after the surgery.

“I think what this shows is that, in the mitral valve surgery patient who has persistent atrial fibrillation, you will achieve better rhythm control by performing ablation, without any increase in mortality or other adverse cardiac events,” stated Dr. Gillinov.

However, the analysis showed that patients who underwent ablation with the mitral valve surgery were 2.5 times more likely to require the implantation of a pacemaker in the year following surgery. The reason for this difference is unknown and warrants further study, Dr. Gillinov said.

The ACC press release explained that because there are several tools and techniques physicians can choose when performing surgical ablation, the study investigators decided to randomly assign patients who underwent ablation to either pulmonary vein isolation or a biatrial Maze lesion. The analysis showed no significant differences in the outcomes for patients undergoing the two procedure types, although a larger study would help to elucidate any differences, advised Dr. Gillinov.

The study patients have only been tracked for 1 year, so the results do not yet provide a clear picture of the full spectrum of potential differences in cardiovascular outcomes. The investigators will continue to track patients to assess any long-term differences in survival, hospitalization, stroke, and other outcomes, noted the ACC announcement.