Objectives

This study compared the degree of left ventricular reverse remodeling in patients with severe ischemic mitral regurgitation who had either mitral valve repair or mitral valve replacement surgery.

Background

Mitral regurgitation (MR) is a condition where the mitral valve, the valve that separates the left atrium from the left ventricle, allows blood to flow back into the left atrium during the systole or contraction phase of the heart. Significant backflow is usually symptomatic and can lead to increased pressure in the pulmonary veins, resulting in pulmonary congestion; a condition of fluid build-up in the lungs. Primary MR occurs because of an abnormal mitral valve whereas secondary MR results from an abnormality of the left ventricle. Ischemic mitral valve regurgitation, a type of secondary MR, is usually attributed to a history of myocardial infarction where the area of the heart muscle that supports the mitral valve, has been damaged. Outcomes for those with ischemic mitral regurgitation are usually poor as their risk of mortality doubles. In an attempt to reduce the elevated risk of mortality, surgeons often recommend mitral valve repair over replacement. This recommendation is based on current literature but often lacks a side-by-side comparison of interventions.

Participants

251 participants enrolled in this study and were randomly assigned to one of two surgical groups with 126 participants assigned to the mitral-valve repair group and 125 assigned to the mitral-valve replacement group.

To be eligible for the study, participants needed to be 18 years or older and have a diagnosis of coronary artery disease and severe ischemic mitral regurgitation as determined by a clinical site echocardiographer. Several factors excluded a patient’s eligibility for the study including: pregnancy, structural mitral valve disease, ruptured papillary muscle, severe pulmonary hypertension, and a history of myocardial infarction requiring intervention in the preceding 7 days before surgery.

Design

The technique selected for mitral-valve replacement was one which attempted complete preservation of the subvalvular apparatus. This apparatus functions to maintain the structure of the valve leaflets during ventricular contraction and is comprised of an anterior and posterior papillary muscle, the chordae tendineae, and valve leaflets.

The mitral valve repair procedure was one in which the surgeon used annuloplasty; a technique in which a rigid or semirigid circular device is implanted to tighten or reinforce the ring around the valve. The type of annuloplasty ring and technique of suture placement were chosen according to the preference of the surgeon.

For either procedure, cardiologists were given guidelines regarding medical therapies which could include aspirin, lipid-lowering agents, beta-blockers, and angiotensin converting enzyme (ACE) inhibitors, as well as cardiac resynchronization/cardioversion therapy.

Interventions took place at 22 clinical centers throughout the U.S. and Canada with end points measured at 30 days and at 6, 12, and 24 months. The primary endpoint, at twelve months after surgery, investigated the degree of left ventricular reverse remodeling using transthoracic echocardiography. Secondary endpoints included mortality, a composite of major adverse cardiac or cerebrovascular events, recurrent mitral regurgitation, quality of life, and rehospitalization.

Conclusions

At 12 months, there was no significant difference in survivorship, quality of life, or left ventricular reverse remodeling for those who had either surgical intervention. There was also no significant difference between the two groups in regards to the frequency of adverse events or the number of hospitalizations.

Acker MA, Parides MK, Perrault LP, et al. Mitral-Valve Repair versus Replacement for Severe Ischemic Mitral Regurgitation. The New England journal of medicine. 2014;370(1):23-32. doi:10.1056/NEJMoa1312808.

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