PTCA is a widely used technique in patients post-acute myocardial infarction (AMI) as well as in unstable angina (UA). The precise timing of its application and some aspects of the indication nowadays remains a matter of controversy. Primary PTCA is not generally considered to be the initial treatment of AMI. In contrast, immediate PTCA after thrombolysis has been proposed attempting to decrease the incidence of early reocclusion, improve myocardial salvage, decrease the incidence of postinfarction angina and improve survival. Nevertheless, three recent controlled studies (TAMI, TIMI II and ECSG) have demonstrated that an "aggressive" strategy with obligatory, invasive intervention following thrombolysis does not provide any advantage in terms of survival, rate of reocclusion or improved ventricular function and is, in fact, likely to be harmful. Emergent coronary arteriography after AMI should be reserved for unstable patients with continued or recurrent ischemia in the CCU. In elective basis it should be indicated in all patients with spontaneous or provocable ischemia prior to hospital discharge. If high grade coronary stenoses are identified, the patient should be considered for PTCA or surgical revascularization. In our own experience with coronary arteriography 24 hours to 15 days after intravenous thrombolysis with SK, PTCA is anatomically feasible in 44% of all the patients and in 60% of those showing a patent vessel. However, when indicated because of postinfarction angina or a positive stress test, PTCA was performed only in 22%, some of them presenting with a totally occluded vessel. In case of stenosis lesser than 100% the dilation success rate is slightly lower than that of out entire series (84% vs 88%), but the incidence of acute occlusion is significantly higher (10% vs 6%), particularly in patients with angiographic evidence of intracoronary thrombi. The incidence of "non-significant" (less than 70%) stenosis spontaneously increases when the coronary arteriography is performed late during hospitalization (34% vs 17% when the patient is studied in the first 24-48 hours).(ABSTRACT TRUNCATED AT 250 WORDS)