Between May 1980 and July 1985, 70 patients underwent percutaneous transluminal coronary angioplasty (PTCA) for angina occurring 24 hours after and within 30 days of acute myocardial infarction (32 with Q-wave infarction and 38 with non-Q-wave infarction). One-vessel disease was present in 42 (60%) and multivessel in 28 (40%); the mean ejection fraction was 0.56 (greater than or equal to 0.50 in 77% of patients). PTCA was successful in 56 patients (80%) and after introduction of steerable dilating systems in February 1983 this rate became 86%. The success rate for complete occlusions was 76%. The interval from myocardial infarction to PTCA was similar in patients with successful dilation (12.7 +/- 8.1 days) and those without (13.4 +/- 8.0 days). PTCA failed in 14 patients (20%); 8 underwent emergency coronary artery bypass for acute occlusion and 4 of 6 patients whose lesions could not be crossed had elective bypass surgery. There was 1 operative death. No patient sustained a Q-wave infarction. Three patients had non-Q-wave infarctions after technically successful PTCAs. Mean follow-up was 27 months (6 to 67 months). Of the 56 patients successfully dilated, 14 (25%) had 15 cardiac events during follow-up: death (1), non-Q-wave infarction (2), repeat PTCA (7), coronary bypass (4) and recurrence of severe angina (1). The cumulative mortality was 3% and the reinfarction rate was 7% (no Q-wave reinfarctions). Forty-two (60%) of the 70 patients were free of complicating events acutely and during follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)