The aim of this study was to determine whether the percentage of akinesia on echocardiography during the acute phase of transmural anterior myocardial infarction could predict secondary left ventricular dilatation. The study group comprised 24 patients (18 men and 6 women) with an average age of 59 years. The patients underwent two echocardiographic examinations, the first during the acute (< 72 hours) phase and the second, 6 months later. Ventricular volumes were calculated by the ellipse monoplane method in the apical 4 chamber view. The percentage of akinesia was defined as the ratio between the length of the akinetic segment and the left ventricular end diastolic perimeter in the apical 4 chamber view. An increase in end diastolic volume (83 +/- 25 vs 62 +/- 18 ml/m2; p < 0.01) and in end systolic volume (51 +/- 27 vs 34 +/- 11 ml/m2; p < 0.01) was observed 6 months after infarction without a significant change in ejection fractions (42 +/- 17% vs 44 +/- 10%). The percentage of akinesia in the acute phase was > 30% in 15 patients (Group I) and < 30% in 9 patients (Group II). The increase in ventricular volumes at 6 months after infarction was significant in Group I (p < 0.02) but not in Group II. At 6 months after infarction, the end systolic volumes were greater (60 +/- 27 vs 37 +/- 22 ml/m2, p < 0.5) and the ejection fractions were lower (35 +/- 13% vs 53 +/- 18%, p < 0.01) in Group I than in Group II.(ABSTRACT TRUNCATED AT 250 WORDS)