In 76% of all patients in whom thrombolysis was successful a residual stenosis exceeding 75% luminal diameter was found. Some patients suffered from single, others from multi-vessel disease. In single vessel diseases immediate intracoronary balloon dilatation of the residual stenosis is feasible. In multi-vessel diseases an aortocoronary bypass operation may follow. In a non-randomized study of 411 patients treated successfully with thrombolysis the best prognosis during the hospital phase and the subsequent 12 months was found in those who had had bypass surgery; patients treated with PTCA had the next best prognosis, and those treated with medical therapy had the worst. In a randomized study 95 patients were treated with thrombolysis alone and another 95 patients with thrombolysis plus immediate PTCA. PTCA diminished the degree of stenosis significantly (78 +/- 16% vs. 33 +/- 21%; p less than 0.001). This value remained constant during the following four weeks (30 +/- 26%). The clinical course, segmental wall motion and myocardial perfusion were more favourable in the PTCA group. No differences were found regarding spontaneous and inducible ventricular electrical vulnerability. Immediate PTCA without prior thrombolysis was performed in 27 patients with overt cardiogenic shock. The clinical mortality was significantly lower than in comparative studies. Recanalisation was successful in 24 of 27 patients. PTCA is complementary to successful thrombolysis in acute myocardial infarction to improve the prognosis and myocardial perfusion.