Intravenous fibrinolytic therapy of acute myocardial infarction: new perspectives from plasminogen activators?
The early treatment of acute myocardial infarction has changed rapidly in recent years. Given the fact that an occlusive coronary thrombus can be found in most infarct patients within 4 h after clinical symptoms, the idea of instituting medical or mechanical recanalization of the occluded vessel is intriguing. However, invasive measures are time consuming, expensive and not freely available to a great number of patients. Thus, only i.v. fibrinolytic therapy of acute myocardial infarction will gain wider application in the near future. Several concepts have been worked out, one of which uses a high-dosage streptokinase or urokinase regimen. A different therapeutic alternative has been made possible by the development of selective fibrinolytic substances, such as the tissue-type plasminogen activator (t-PA) or the anisoylated plasminogen-streptokinase activator complex (APSAC). Preliminary clinical data have shown that the coronary artery patency rate achieved after i.v. administration of t-PA or APSAC is higher than that after conventional treatment with streptokinase or urokinase. The incidence of severe bleeding complications is low and comparable in these studies. However, until myocardial salvage has been demonstrated with early i.v. fibrinolytic therapy in acute myocardial infarction in a placebo-controlled randomized trial, this therapeutic concept will still be unsettled.