LCZ696 is a dual-acting inhibitor of the renin-angiotensin-aldosterone system (RAAS) and neutral endopeptidase (NEP). As LCZ696 offers the therapeutic advantages of concomitantly blocking both RAAS and NEP, LCZ696 was more effective in reducing the risk of death from cardiovascular causes or hospitalization for heart failure in patients with chronic heart failure than ACE inhibitor. Because NEP is involved in the metabolism of a number of vasoactive peptides such as natriuretic peptides, NEP inhibitor has vasodilating effects, facilitates sodium excretion and has profound effects on LV remodeling. Trials of hypertension and heart failure with a preserved ejection fraction also showed that LCZ696 had greater hemodynamic and neurohormonal effects than ARB alone. To date, there has been no proven pharmacological therapy to improve functional MR, and the development of medical therapy should be at the forefront of research considering the limited role of surgery in managing functional MR. Investigators hypothesize that LCZ696 is superior to ARB alone in improving functional MR in patients with LV dysfunction and functional MR via synergistic effects of NEP and RAAS inhibition on LV remodeling, and try to examine this hypothesis in a multicenter, double-blind, randomized comparison study using echocardiography.