AHA.15: Two-year survival similar among surgical options for severe ischemic mitral regurgitation

After two years, patients who underwent mitral valve repair or replacement for severe ischemic mitral regurgitation had no statistically significant difference in mortality, overall readmissions or serious adverse events, according to a randomized trial. However, patients in the repair group had a higher rate of recurrent mitral regurgitation and were more likely to have a heart failure adverse event, cardiovascular readmission and quality of life score.

Lead researcher Daniel Goldstein, MD, a professor of cardiovascular and thoracic surgery at the Montefiore Medical Center and Albert Einstein College of Medicine in New York, presented the results on Nov. 9 at the American Heart Association (AHA) Scientific Sessions. The findings were simultaneously published online in the New England Journal of Medicine.

“Replacement provides a more durable correction of severe ischemic mitral regurgitation,” Goldstein said.

The researchers mentioned that ischemic mitral regurgitation is a serious consequence of coronary artery disease and is associated with a 1-year mortality rate of 15 percent to 40 percent. Goldstein said the benefit of surgical revascularization in treating severe ischemic mitral regurgitation is “undisputed,” although the best surgical option remains unclear.

Previous studies showed mitral valve repair was associated with lower perioperative morbidity and mortality, but Goldstein said the procedure can result in recurrence of mitral regurgitation and functional mitral stenosis. Meanwhile, chordal-sparing mitral valve replacement has been shown to provide a more durable correction than mitral valve repair, it was associated with higher perioperative mortality and potential long-term complications.

“At present, no evidence-based guidance exists on the best surgical option,” Goldstein said.

In this study, the researchers enrolled 251 patients with chronic severe ischemic mitral regurgitation and coronary artery disease and randomized them to undergo mitral valve repair or chordal-sparing mitral valve replacement. The Cardiothoracic Surgical Trials Network conducted the study, which was funded by the National Institutes of Health.

The surgeons used an approved complete rigid or semirigid annuloplasty ring when performing mitral valve repair, while mitral valve replacement included complete preservation of the subvalvular apparatus. The cardiologists also prescribed treatments such as aspirin, lipid-lowering agents, beta-blockers and cardiac-resynchronization therapy.

At baseline, the groups were well balanced. The mean age was approximately 68, while 62 percent of patients were male and nearly 75 percent of patients had a history of heart failure and a concomitant CABG procedure.

The mean left ventricular end-systolic volume index (LVESVI) at baseline was 61.1 ml per square meter in patients undergoing mitral valve repair and 65.7 ml per square meter in patients undergoing mitral valve replacement. Goldstein said the LVESVI measures the left ventricular reverse remodeling process.

During the trial, 11 patients assigned to the repair group underwent replacement and one patient assigned to the replacement group underwent repair.

At two years, the mean LVESVI among surviving patients was 52.6 ml per square meter in the repair group and 60.6 ml per square meter in the replacement group, while the mean left ventricular ejection fraction was 42.5 percent and 37.6 percent, respectively.

The 2-year mortality rates were 19 percent in the repair group and 23.2 percent in the replacement group. The difference was not statistically significant. Goldstein said most of the deaths occurred during the first year.

“Though the study did not have the power to make definitive conclusions, these 2-year mortality figures are consistent with those reported in contemporary, retrospective series in the literature,” Goldstein said.

Further, 58.8 percent of patients in the repair group and 3.8 percent of patients in the replacement group had recurrent moderate or severe mitral regurgitation at some point during the 2-year follow-up period. Severe mitral regurgitation occurred in 14 percent of patients with recurrence in the repair group and no patients with recurrence in the replacement group.

At two years, patients in the repair group had significantly more serious heart failure events and a significantly higher rate of readmissions for cardiovascular causes. However, the rates of major adverse cardiac or cerebrovascular events and overall readmission rates did not differ significantly between the groups.

Goldstein added that 68 percent of patients in the repair group and 29 percent of patients in the replacement group had moderate or greater mitral regurgitation, a need for reintervention on the mitral valve and/or had died after two years.

Goldstein said the study had a few limitations, including that its primary endpoint (LVESVI) was echocardiographically derived parameter and not a clinical end point. However, he mentioned left ventricular remodeling as measured by LVESVI predicts poor prognosis and is a widely accepted surrogate with a strong and consistent relationship with clinical outcomes such as functional status, rehospitalization and survival.

In addition, he said a 5-year follow-up period would be ideal, and he noted that the study did not evaluate subvalvular procedures.

“We believe longer follow-up is needed to track outcomes and place the trade-off between replacement and repair in sharper relief,” Goldstein said. “Further research is necessary to help identify patients for whom repair may provide a durable correction of severe ischemic mitral regurgitation.”