Functional MR is caused by adverse left ventricular remodeling after myocardial injury and associated with an increased incidence of heart failure and death. 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. As LCZ696 is a dual-acting inhibitor of the renin-angiotensin-aldosterone system (RAAS) and neutral endopeptidase (NEP), LCZ696 has greater hemodynamic and neurohormonal effects than ARB alone. Investigators try to examine the hypothesis that LCZ696 is superior to ARB alone in improving functional MR in patients with LV dysfunction and functional MR.