Ischemic mitral regurgitation: Mechanisms and echocardiographic classification

Chronic ischemic mitral regurgitation (IMR) is a common complication of myocardial infarction and severely affects cardiovascular mortality and morbidity. Multiple pathophysiologic mechanisms, such as left ventricular (LV) remodeling and dysfunction, annular dilation/dysfunction, and mechanical dyssynchrony, are involved in generating IMR, each of them having different weight. However, the prerequisite to initially creating regurgitation is the presence of local or global LV remodeling that alters the geometrical relationship between the ventricle and valve apparatus. In the wide spectrum of patients with chronic IMR, the assessment of some echocardiographic parameters, such as tethering pattern, leaflet motion, origin and direction of the regurgitant jets, allows one to identify different specific subgroups of patients subjected to different therapeutic approaches. The aim of medical and/or surgical therapy is to ameliorate heart failure symptoms, and improve LV remodeling and function and the intermediate/long-term outcome. The targets of surgical MV repair involve annulus, leaflets, chordae and ventricles. The restricted annuloplasty is the most commonly adopted surgical procedure that improves heart failure symptoms but not survival when compared to medical therapy and is also subject to a high incidence of late failure (∼30%). There are some preoperative echocardiographic predictors of failure that include valve (degree of valve remodeling, jet characteristics), ventricular (degree of remodeling, diastolic dysfunction) and surgical factors.