Ischemic and functional mitral regurgitation in heart failure: natural history and treatment.

Functional mitral regurgitation (FMR) occurs when normal or nearly normal mitral leaflets are prevented from proper coaptation by underlying left ventricular (LV) dysfunction, mitral annular dilation, or both. FMR is associated with an adverse prognosis in nonischemic or ischemic LV dysfunction. Multiple studies have confirmed that even mild FMR portends a worse prognosis, and that the risk of FMR is independent of LV volumes and other clinical risk factors. FMR can be difficult to quantitate echocardiographically because it is load dependent and can vary considerably from exam to exam. There is a systematic tendency to underestimate FMR severity by echocardiography because the regurgitant orifice in FMR is typically elliptical, but the formula for calculating regurgitant orifice area assumes circular geometry. Treatment of FMR begins with guideline-directed medical therapy (GDMT) for LV dysfunction and heart failure, including cardiac resynchronization, if indicated. Revascularization should be considered for ischemic FMR, when indicated. Finally, mitral valve surgery should be considered in patients undergoing CABG in whom moderate or greater FMR is present, and also when severe symptomatic FMR persists despite optimal GDMT and revascularization. Percutaneous options for treatment of FMR are in development but are not currently approved in the US.