Hemodynamic evaluations of 130 patients with acute myocardial infarction were performed by right and/or left heart catheterization. 115 patients were subdivided in six groups by the pulmonary artery mean pressure (PMP)-left ventricular stroke work index (LVSWI) relationship: 1) normal LVSWI in relation to PMP (14.8% of all cases); 2) increased LVSWI in relation to PMP (0.9%); 3) moderately reduced LVSWI with increased PMP (severe heart failure-cardiogenic shock) (7.0%); 5) reduced LVSWI with low or normal PMP (22.6%); 6) normal LVSWI with elevated PMP (reduced left ventricular compliance or high pulmonary vascular resistance) (15.7%). 28 cases were studied by right and left heart catheterization; in 10 cases only left heart catheterization was performed. Discriminant analysis on the values measured at the first stage of hemodynamic monitoring was conducted: this type of mathematical analysis seemed to provide a more useful prognostic index.