Ablation during mitral valve surgery offers up mixed results




SAN DIEGO – Surgical ablation of atrial fibrillation at the time of mitral valve surgery provides significantly greater rhythm control than mitral valve surgery alone, a study showed.

Freedom from atrial fibrillation (AF) at both 6 months and 1 year was 63% in patients undergoing mitral valve surgery (MVS) plus ablation and 29% in those undergoing MVS alone, a statistically significant difference.

However, patients who had ablation plus MVS were 2.5 times more likely to have a permanent pacemaker implanted than were those who had MVS alone, at 21.5% and 8.1%, respectively, also a significant difference.

Dr. A. Marc Gillinov Patrice Wendling/Frontline Medical News

Dr. A. Marc Gillinov

Ablation did not increase mortality or major adverse cardiac or cerebrovascular events, Dr. A. Marc Gillinov said at the annual meeting of the American College of Cardiology.

Preoperative AF is present in up to 50% of patients undergoing mitral valve operations and is associated with an increased risk of death and stroke.

The study enrolled 260 relatively elderly patients (mean age 69 years) with AF that was persistent (non–self-terminating for at least 7 days) or long-standing persistent (continuous for at least a year), in addition to mitral valve disease. A total of 133 patients were randomly assigned to MVS plus ablation and 127 to MVS alone. The ablation group was further randomized to pulmonary vein isolation or a biatrial maze procedure; all underwent closure of the left atrial appendage.

There was no significant difference in freedom from AF at 6 months and 1 year between patients who had pulmonary vein isolation or a biatrial maze procedure, at 61% and 66%, respectively, said Dr. Gillinov, a cardiac surgeon at Cleveland Clinic.

One-year mortality was similar among all patients undergoing MVS plus ablation vs. MVS alone, at 6.8% and 8.7%.

The two groups also had similar Short Form-12 questionnaire scores for physical function and mental function, although AF occurring at least once daily was significantly less common with ablation, at 19.8%, compared with 45.2% in the MVS-alone patients, he said.

The heart rhythm endpoint was “stringent,” with 3-day Holter monitors obtained at both 6 and 12 months and repeat ablation procedures and death considered treatment failures, Dr. Gillinov said.

He acknowledged that 20% of patients did not have data for the primary endpoint and that the endpoint was not a clinical one, but said a trial with mortality or stroke as the endpoint would require more than 1,000 patients and many years follow-up.

Regarding whether ablation should now be performed routinely, “the glass is half full or half empty,” remarked discussant Dr. Bernard Gersh of Mayo Clinic in Rochester, Minn. “On one hand, you have shown less atrial fibrillation [with ablation], but no effect on quality of life, and the price to be paid was a higher rate of pacemaker implantation,” he said.

The pacemaker implantation rate was higher than expected – 17% in-hospital – and does represent a potential cost, but he would routinely do a maze procedure, Dr. Gillinov said.

Discussant Dr. Alice Jacobs of the Cardiovascular Center at Boston Medical Center, said she expected Dr. Gillinov to say the procedure should not be used in everyone given the lack of benefit in stroke, probably because they tied off the left atrium appendage, and the increase in pacemaker implantations.

About half of the pacemaker implantations were due to atrioventricular block, possibly a consequence of the valve surgery, and one-third to sinus-node dysfunction, which is common in elderly patients, Dr. Gillinov explained.

The study was funded by the National Institutes of Health and the Canadian Institutes of Health Research. Dr. Gillinov reported serving as a consultant/speaker for AtriCure, Medtronic, On-X, Edwards, and Tendyne; research funding from St. Jude Medical; an equity interest in Clear Catheter; and that his institution receives royalties from AtriCure for a left atrial appendage occlusion device.

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