We studied 120 patients (M:F 105:15, mean age 57.5 ؎ l0.l years) with acute myocardial infarction (MI) successfully treated with percutaneous coronary angioplasty (PTCA) to analyze the influence of the resolution of the ST segment elevation and depression after intervention to 1 month composite endpoints of reinfarction or reocclusion, development of congestive heart failure (CF) and death. Sum of preintervention and postintervention ST segment elevation and depression and the rate of resolution of these ST segment elevations and depressions were recorded for every patient. A total of 17 (14.2 %) composite endpoint events (events group) were recorded (7 reocclusion or recurrent MI, 9 CF, and 1 death). On univariate analysis, events group patients were older (53.3 ؎ 9.9 vs. 58.8 ؎ 9.1 years, P ؍ 0.032), had lesser resolution of ST segment elevations (85 ؎ 24 % vs. 44 ؎ 55%, P ؍ 0.017) and depression (72 ؎ 26% vs. 52 ؎ 30%, P ؍ 0.009), had greater preintervention ST segment elevation (17.49 ؎ 12.95 mm vs. 28.38 ؎ 20.41 mm, P ؍ 0.045), had lower ejection fraction (59.3 ؎ 10.2% vs. 43.6 ؎ 9.4%, P F 0.001), and had more frequent multivessel disease (71% vs. 47%, P ؍ 0.048) compared to the nonevents group. Time from angina to reperfusion, residual stenosis, sex, infarct location and infarctrelated vessel distribution were similar. On multivariate analysis (logistic regression with backward likelihood ratio) only older age (P ؍ 0.0752), lesser rate of resolution of ST segment depression (P ؍ 0.0262) and lower ejection fractions (P ؍ 0.0014) were retained as predictors of the composite endpoints. Relative risk conferred by less than 50% resolution of ST segment depressions for composite endpoints were 3.78 (95% CI 1.63-8.73). We conclude that the lack of resolution of the sum of reciprocal ST segment depressions identifies a subgroup of acute MI patients with greater morbidity after primary PTCA.