To determine the prognostic value of some echocardiographic indices of left ventricular function (ejection fraction, wall motion score index, left ventricular dimension) in the first year after acute myocardial infarction, we studied prospectively 162 consecutive patients (mean age: 61 +/- 11) who survived the hospital phase of a first acute myocardial infarction. Two-dimensional echocardiography was performed at hospital discharge (mean: 20 +/- 3 days after admission). For the analysis of wall motion, an 11 segment model of the left ventricle was used; from the scoring system of segmental ventricular function (1 = normal, 2 = hypokinetic, 3 = akinetic, 4 = dyskinetic, 5 = aneurysmal) we derived the wall motion score index (sum of assigned number to each segment/11). The echocardiographic ejection fraction was determined using the monoplane ellipsoid formula for the calculation of end diastolic and end systolic volumes in apical four-chamber and two-chamber views; the assumed ejection fraction was the mean value resulting from values of ejection fraction calculated in the two views. The follow-up was protracted from 13 to 36 months (mean: 22 months). Fourteen patients (9%) died as a result of cardiac events within 13 months of myocardial infarction. Of the patients with ejection fraction greater than or equal to 45% (81/162 = 50%) two died (first year mortality = 2.4%); of those with 35-45% ejection fraction (58/162 = 35%) two died (first year mortality = 3.5%); while of those with less than or equal to 35% ejection fraction (25/162 = 15%) ten died (first year mortality = 40%). Of the patients with wall motion score index less than 1.5 (76/162 = 47%) none died in the follow-up period; of those with score index between 1.5 and 1.9 (61/162 = 37%) four died (first year mortality = 7%); of those with score index greater than or equal to 1.9 (25/162 = 15%) ten died (first year mortality = 40%). Thus, ejection fraction and score index have the same predictive value for mortality in the first year after a first acute myocardial infarction. However, an interesting datum is that in the sub-group of patients with less than or equal to 35% ejection fraction and score index less than 1.9 the first year mortality was 15%, while in the sub-group with less than or equal to 35% but score index greater than or equal to 1.9 the first year mortality was 57%.(ABSTRACT TRUNCATED AT 400 WORDS)