Successful direct PTCA on LAD after first episode of acute myocardial infarction: does it improve cardiac function? Patients who received direct percutaneous transluminal coronary angioplasty (PTCA) after acute mycardial infarction and maintained potency but with unimproved cardiac function were studied. In 15 patients, the first episode of acute myocardial infarction was caused by a left anterior descending branch lesion; 11 had an ejection fraction of 50% or more in the left ventriculogram in the follow-up period (improved group), and 4 patients had ejection fraction of less than 50% (unimproved group). There was so significant difference between the groups in the mean time between the onset of infarction and revascularization (improved group, 259.3 +/- 76.9 min; unimproved group, 168.0 +/- 101.6 min) or in the sigma Q. which was the sum of the Q wave depth of V2, V3, and V4 at the time of admission (improved group, 12.1 +/- 15.6 mm; unimproved group 29.8 +/- 13.4 mm). The maximum creatine kinase concentration was significantly higher in the unimproved group (improved group 2670 +/- 893 IU/L; unimproved group, 7243 +/- 1928 IU/L, p less than 0.05), and the time taken from the onset to reach its peak was significantly shorter in the unimproved group (improved group, 13.0 +/- 5.1 hr; unimproved group, 6.8 +/- 1.3 hr, p less than 0.05.) These results suggest the probability of sudden deterioration of myocardium, and factors other than microcirculatory thromboembolism should be considered as the cause of unimproved cardiac function after successful direct PTCA. 