Echocardiographic Evaluation of Papillary Muscle function in Ischemic Mitral Regurgitation.

Ischemic mitral regurgitation is defined as mitral regurgitation due to coronary artery disease with structurally normal mitral valve leaflet and chordae. Some authors prefer to use the term as functional mirtal regurgitation. But functional mitral regurgitation can occur in idiopathic dilated cardiomyopathy without coronary artery disease. So Ischemic mitral regurgitation and functional mitral regurgitation are not synonymous. The incidence of coronary artery diseases in rural and urban population in India is reported to be between 14.8 per thousand to 65.4 per thousand(2). Patients with coronary artery diseases during their course may develop complications such as arrhythmias, mechanical complications (ventricular septal rupture, Ischemic mitral regurgitation) and pump failure. Ischemic mitral regurgitation occurs in approximately 20% of patients after myocardial infarction and 56% of patients with heart failure due to ischemic or non ischemic cardiomyopathy. Ischemic mitral regurgitation can occur in coronary artery disease both during acute phase and chronic phase. Ischemic mitral regurgitation is more common in inferior wall myocardial infarction than anterior wall myocardial infarction. There is a graded independent association between the severity of ischemic MR and the development of Heart failure after myocardial infarction. Even mild ischemic MR is associated with an increase in the risk of heart failure. Ischemic mitral regurgitation is an independent prognostic factor in patients with chest pain even without myocardial infarction. Advancing age, female gender, multiple vessel coronary artery disease, congestive heart failure, recurrent ischemia, large infarct size, and prior acute myocardial infarction are all risk factors for developing IMR. THE AIM OF THE STUDY: 1) To assess the mechanisms of ischemic mitral regurgitation in patients with old myocardial infarction. 2) To assess the role of Tissue Doppler imaging in evaluation of papillary muscle function. 3) To assess the contribution of papillary muscle dysfunction in the pathogenesis of ischemic mitral regurgitation. CONCLUSIONS: 1. Mitral leaflet tethering distance is consistently directly proportional to severity of Ischemic mitral regurgitation. 2. Papillary muscle function is better assessed by tissue Doppler echo than M Mode and 2D echocardiography. 3. Papillary muscle dysfunction is not an independent determinant of ischemic MR in all cases. 4. Papillary muscle dysfunction attenuates ischemic MR in patients with old inferior wall MI with increased left ventricular sphericity due to focal remodeling. 5. Role of papillary muscle dysfunction in ischemic MR is still elusive and varies depending on factors such as location of myocardial infarction and extent of left ventricular remodeling.