Ischemic mitral regurgitation: pathophysiology, diagnosis, and treatment

Secondary or 'functional' mitral regurgitation (MR) is often due to ischemic heart disease that results in disordered left ventricle and mitral valve geometry. In patients with coronary disease, concomitant MR results in worse morbidity and mortality. Coronary artery disease may result in annular dilation due to left ventricle cavity dilation, excessive leaflet motion, impaired leaflet motion due to leaflet tethering and papillary muscle displacement, and/or decreased mitral valve closing forces due to systolic dysfunction. Although transthoracic echocardiography is the first step in the diagnosis of ischemic MR, transesophageal and three-dimensional echocardiography are often useful adjuncts to better understand the mechanism(s) of disease and planning repair. Furthermore, noninvasive evaluation of ischemia and viability may provide important prognostic information. Medical therapy for ischemic MR is directed at the underlying ischemic substrate and concomitant systolic dysfunction, and consists of β-blockers and vasodilators. Percutaneous strategies for repair are currently under investigation, and have shown promising results. Surgical repair is favored over replacement, and is generally recommended for patients with moderate or severe MR undergoing coronary artery bypass. Unfortunately, long-term freedom from MR is elusive even with surgical repair, and trials are currently underway to determine the best approach to treatment in patients with moderate disease.