We attempted to evaluate left ventricular performance from the shortest distance between the mitral leaflets coaptation and the interventricular septum at end-systole (MVC-IVS distance). The subjects were 37 patients with coronary artery disease (CAD) with prior myocardial infarction (MI), 8 with CAD without prior MI, 22 with atypical chest pain, and 4 with aortic regurgitation. The MVC-IVS distance was measured on a two-dimensional echocardiogram obtained from the parasternal or apical long-axis view and frozen at end-systole. Left ventricular end-systolic volume and end-diastolic volume were obtained by left ventriculography, and the left ventricular ejection fraction was calculated. A significant positive correlation was observed between the MVC-IVS distance and the end-systolic volume (r = 0.83, p less than 0.001); a close correlation was observed between the MVC-IVS distance end-systolic volume and ejection fraction by monoexponential fitting (r = -0.91, p less than 0.001). Thus, a significant negative correlation was observed between the MVC-IVS distance and the left ventricular ejection fraction (LVEF) (r = -0.83, p less than 0.001). An MVC-IVS distance of greater than or equal to 30 mm suggests diagnosis of left ventricular dysfunction (LVEF less than 50%) with high sensitivity (94.4%) and specificity (90.6%), while a value less than 30 mm suggests that the left ventricular performance is likely to be normal. Thus one can easily evaluate the left ventricular performance noninvasively using this new index.