A 68-year-old female was admitted for sudden onset of chest pain. She received a successful percutaneus coronary intervension for total occlusion in the diagonal artery, but continued to develop progressive heart failure. A chest X-ray showed right pulmonary edema without cardiomegaly, and an echocardiogram revealed massive mitral regurgitation with prolapse in the anterior mitral leaflet due to a rupture in the papillary muscle. An emergency operation was conducted using routine cardiopulmonary bypass. There was complete rupture in the anterior papillary muscle. Mitral valve replacement with posterior mitral leaflet preservation was performed using a size 25 mm Carbomedics prosthetic valve. The postoperative course was uneventful, and she was discharged on postoperative day 29 in New York Heart Association class I. Postoperative pathological findings showed necrosis in the papillary muscle with inflammatory changes. Early diagnosis, prompt medical stabilization, and aggressive surgical intervention are essential to save such a group of patient.