Successful thrombolysis with reperfusion and salvage of jeopardized myocardium frequently necessitates invasive therapeutic strategies such as angioplasty or bypass surgery. Medical treatment in this situation has to consider the possibility of recurrence of infarction before invasive measures can be obtained. It must be specially directed towards preventing such an event, besides applying therapeutic measures in the acute and subacute phase after myocardial infarction. Several different therapeutic principles were considered: 1. In the days after thrombolysis with or without PTCA anticoagulants, mostly in the form of heparin, are used routinely in an attempt to prevent reocclusion and reduce thromboembolic complications. The latter indication seems to yield the most benefit of this type of drug. 2. Platelet-modifying drugs reduce the risk of reocclusion after thrombolysis and PTCA. The vein graft patency seems to be higher after aspirin treatment than after coumarine therapy. A reduction of coronary events was reported especially in patients with non Q-wave infarction, a situation particularly liable for reinfarction. 3. Calcium antagonists are used widely after PTCA to attenuate coronary spasm. No global beneficial effects have been observed after bypass surgery and in the therapy of acute myocardial infarction. Special indications e.g. for certain types for arrhythmias remain unchanged after thrombolysis, PTCA and bypass surgery. 4. Antianginal drugs with nitrates and betablockers are indicated to relieve symptoms in the acute phase. In chronic treatment, prevention of reinfarction and reduction of mortality was reported after the use of betablockers, the latter mainly by increasing the fibrillation threshold, thus reducing deaths due to arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)