The evaluation of left ventricular ejection fraction (LVEF) may be troublesome in difficult clinical settings in patients with coronary artery disease (CAD). The aim of this study was to compare 2 simple geometrical and nongeometrical methods of LVEF evaluation that could overcome the typical technical limitations of ultrasound examination. The authors studied 26 patients with proven CAD (63+/-10 years) who underwent left ventricular (LV) catheterization and coronary angiography during the hospital stay. A complete 2D-Doppler echocardiography was performed and LVEF was evaluated with the formula by Wyatt (W-LVEF), which relates the left ventricle to a biplane ellipsoidal figure, and by the myocardial performance index (MPI) formula (MPI-LVEF), MPI being an index of systodiastolic function. Mean MPI-LVEF was 41+/-8% and was significantly lower with respect to contrast angiography (52+/-14%, p = 0.0003) and to W-LVEF (49+/-13%, p = 0.0009). There was no statistically significant correlation between MPI-LVEF and geometric (either angiographic or ultrasound) LVEF. Bland-Altman analysis showed lack of agreement between MPI-LVEF and any other method evaluated in the study. MPI-LVEF may not be reliable and accurate for the evaluation of systolic function in patients with CAD. Nonetheless, the evaluation of global LV function by means of MPI may represent a valuable and affordable alternative to expensive and time-consuming methods, especially in the presence of difficult technical settings.