ISCHEMIC MITRAL REGURGITATION - TO REPAIR OR REPLACE? LOOKING BEYOND THE VALVE.

Ischemic mitral regurgitation (IMR) is a frequent and serious complication of coronary artery disease, associated with considerable patient increased mortality and morbidity. While the benefits of optimal medical therapy and surgical revascularization, when indicated, are uncontested in moderate to severe cases, the ideal surgical approach to the valve, if any, is yet to be established. Mitral valve repair has established benefits over replacement in primary mitral regurgitation, but its superiority in the treatment of functional regurgitation has not been replicated. Differing outcomes likely stem from the distinct IMR pathophysiology. Unlike its degenerative counterparts, IMR does not derive from direct damage to the valve leaflets, but rather from dysfunction of its sub-valvular apparatus and the left ventricular wall, in the context of acute or chronic ischaemia. Echocardiographic data points to remodelling of the left ventricle, with subsequent papillary muscle displacement, increased leaflet tethering and inefficient coaptation, as the main responsible mechanism for ischemic mitral regurgitation. Neither mitral valve repair nor replacement directly address these issues, with the appearance of the first randomized trials supporting replacement as the more durable option. However, new subvalvular procedures are improving the stability of repair techniques and the debate is long from settled. The purpose of this review is to analyse the currently available data, couple it with our understanding of IMR's pathophysiology and compare the different outcomes for mitral valve repair and  replacement.