The addition of mitral valve (MV) repair (a valve of the heart) to coronary artery bypass grafting (CABG), a type of open-heart surgery, did not result in significant benefit to the patient and was associated with increased risk of neurological events. Therefore, the routine addition of MV repair to CABG in patients with moderate IMR did not demonstrate a clinically meaningful advantage.

The Cardiothoracic Surgical Trials Network (CTSN) is reporting results for the first time from a clinical trial of patients who have a complication of coronary heart disease known as moderate ischemic mitral regurgitation (IMR). Study findings were presented by senior study author Robert Michler, M.D., professor and chairman, Department of Cardiothoracic and Vascular Surgery, Montefiore Medical Center and Albert Einstein College of Medicine, and co-director of The Montefiore Einstein Center for Heart and Vascular Care, at the American Heart Association’s Scientific Sessions 2014 and published simultaneously in the New England Journal of Medicine.

“The results of this study suggest there is little benefit to what is often considered a routine addition to the open-heart procedure of CABG for patients with moderate IMR,” said Dr. Michler. “Although the one-year data are very compelling, long-term follow-up is necessary to determine whether the lower prevalence of IMR seen at one year will translate into any clinical benefit for patients undergoing mitral valve repair.”

IMR occurs when blood backflows into the left atrium from the left ventricle of the heart due to improper closure of the MV. The condition often develops as a complication of a heart attack and subsequent enlargement of the left ventricle, the heart's main pumping chamber. Functional IMR affects 1.6 million to 2.8 million patients in the U.S. and is associated with a doubling in mortality among patients with mild or greater degrees of mitral regurgitation after a heart attack. The optimal treatment of IMR remains controversial and unclear. 

The prospective, multi-center, controlled clinical trial randomly assigned 301 patients with moderate IMR to CABG alone or CABG with MV repair. The primary endpoint was left ventricular end systolic volume (LVESVI) at one-year, assessed using a Wilcoxon rank sum test categorizing deaths as the lowest LVESVI rank.

One-year mortality was 6.7 percent in CABG/MV repair patients versus 7.3 percent in CABG patients. There were no observed differences in MACCE, death, readmissions, functional status or quality-of-life at one-year.

The CTSN core clinical centers in the U.S. and Canada include Cleveland Clinic Foundation, Duke University, Emory University, Montefiore Einstein Heart Center, Montreal Heart Institute, University of Virginia, University of Pennsylvania, and 19 Consortium sites. Icahn School of Medicine at Mount Sinai, is where the CTSN’s DCC is based which directs each of its clinical trial’s design, methodologies, ethical research concerns, study data, analysis and reporting.

This study was presented as the Late-Breaking Clinical Trial (Abstract 49403): The Surgical Treatment of Moderate Ischemic Mitral Regurgitation: A Randomized Clinical Trial From The Cardiothoracic Surgical Trials Network.