Mitral Regurgitation Due to Degenerative Mitral-Valve Disease

A 44-year-old man presents with dyspnea and new atrial fibrillation. He received a diagnosis of mitral regurgitation at 28 years of age, after physical examination revealed a midsystolic click and late-systolic murmur; echocardiography performed at that time showed mitral-valve prolapse with mild late-systolic mitral regurgitation and normal left ventricular size and function. He has not seen a physician in many years. Physical examination reveals a holosystolic murmur and a soft S-3 sound. Repeat echocardiography shows a flail posterior leaflet and moderately severe mitral regurgitation. How should this case be managed?