Medical Therapy of Acute Myocardial Infarction: Part I. Role of Thrombolytic and Antithrombotic Therapy

Thrombolytic therapy has been established as a safe and effective therapeutic strategy in acute myocardial infarction (MD. Its efficacy is improved with early administration, although modest benefits can be demonstrated for up to 12 hours. Tissue plasminogen activator (TPA) appears to offer benefits over streptokinase when administered to patients who present within 4 hours, those with an anterior MI, and who are less than 75 years old. Age alone is not a contraindication for thrombolysis because the risk of bleeding complications in the elderly is outweighed by a significant improvement in mortality. One of the major limitations of thrombolytic therapy in acute MI is reocclusion. Use of adjunctive antithrombotic therapy can reduce the rate of reocclusion following successful thrombolysis. The beneficial role of aspirin is well established. Use of intravenous heparin in conjunction with streptokinase offers no clinical benefit. The efficacy of heparin when administered with other thrombolytic agents remains to be established. These issues and the role of newer antiplatelet and antithrombin agents are being examined in ongoing clinical trials. The objective of this review is to provide the information needed for careful and appropriate judgment in the use of thrombolytic agents and antithrombotic therapy. General principles are emphasized, and specific recommendations are included as guidelines.