This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Medicine
A 59 year old man with severe myxomatous mitral regurgitation is asymptomatic, with a left venricular ejection fraction of 45% and an end systobc diameter index of 2.9 cm/m2. The most appropriate treatment is 
Select and explain. 
A. Mitral valve repair or replacement, B. No treatment, C. ACE inhibitor therapy, D. Digoxin and diuretic therapy
A: Mitral valve repair or replacement
Answer: A: Mitral valve repair or replacement 
Explanation: Surgery for chronic, nonischemic, severe MR is indicated once symptoms occur, especially if valve repair is feasible. Other indications for early consideration of mitral valve repair include recent-onset AF and pulmonary hypeension, defined as a PA pressure >=50 mmHg at rest or >=60 mmHg with exercise. Surgical treatment of chronic, nonischemic severe MR is indicated for asymptomatic patients when LV dysfunction is progressive, with LVEF falling below 60% and/or end-systolic dimension increasing beyond 40 mm. ( Harrison&;s principle of internal medicine,18th edition,pg no.1936 )