We examined the relation between the genotype of the angiotensin-converting enzyme (ACE) gene and the development of left ventricular dysfunction, as assessed by biplane left ventriculograms, after myocardial infarction. Seventy-nine patients (deletion homozygote [DD] = 13; insertion/deletion heterozygote [ID] = 38; insertion homozygote [II] = 28) underwent cardiac catheterization twice for reevaluation of percutaneous transluminal coronary angioplasty. Subjects who had their first cardiac catheterization within 2 months from the onset of myocardial infarction were enrolled. The second cardiac catheterization was performed from 4 to 7 months after the first cardiac catheterization. ACE genotypes were determined by using the polymerase chain reaction. Ejection fraction, and end-diastolic and end-systolic volume indexes at the first cardiac catheterization were not significantly different among the 3 groups. The end-diastolic volume index at the second cardiac catheterization was not significantly different among the 3 groups. Ejection fractions (mean +/- SD) at the second catheterization in the 3 groups were 0.51 +/- 0.15 (DD), 0.56 +/- 0.12 (ID), and 0.62 +/- 0.09 (II) (p = 0.02), and were significantly lower in the DD group than in the II group. The end-systolic volume indexes (mean +/- SD) were 46 +/- 21 (DD), 43 +/- 24 (ID), and 30 +/- 14 (II) ml/m2 (p = 0.01), and were significantly greater in the DD and ID groups than in the II group.(ABSTRACT TRUNCATED AT 250 WORDS)