Eighty-seven mildly symptomatic (NYHA class 1 and 2) patients with chronic rheumatic severe mitral regurgitation underwent a prospective, randomized six-month follow up echocardiographic study, while receiving (orally) either nicorandil (20 mg/day) or enalapril (20 mg/day). Both drugs significantly reduced the left ventricular (LV) end-diastolic and end-systolic dimensions, volume, mass and end-systolic stress. A significant improvement was observed in the ejection fraction of both groups. However, nicorandil caused a greater reduction in absolute LV end-systolic volume, and a greater increase in absolute ejection fraction.