Because secondary functional MR usually develops as a result of LV dysfunction, diuretics, beta blockers, angiotensin-converting-enzyme (ACE) inhibitors or angiotensin receptor blockers (ARB), and aldosterone antagonists are given to patients with functional MR in line with the guidelines in the management of heart failure. However, functional MR appears to remain common despite use of these drugs and current medical treatment is usually insufficient for reducing MR or reversing the adverse LV remodeling. Persistence of functional MR due to the insufficient effectiveness of current medical treatment significantly increases morbidity and mortality, and compared with surgical or percutaneous revascularization, significantly higher mortality was observed in patients managed with medical therapy.