The Role of Heparin in the Thrombolytic Treatment of Acute Myocardial Infarction

Objective: To review the literature to determine the most appropriate role of heparin when using thrombolytic therapy. Data Sources: English-language journal articles published between 1985 and 1991. Study Selection: Ten trials comparing the effects of thrombolytic therapy with and without heparin. Desired outcomes that the authors were interested in were coronary vessel patency, reocclusion, recurrent ischemia, reinfarction, mortality, and bleeding complications. Data Extraction: Studies were assessed based on methodology. Data Synthesis: The concurrent use of heparin with tissue plasminogen activator (tPA) enhances coronary vessel patency without significantly increasing the risk of bleeding complications. The concurrent use of heparin with streptokinase enhances survival; however, the risk of bleeding associated with heparin use is unclear at present. Data are not currently available for anistreplase. Studies are underway to further address the role of heparin with thrombolytic therapy. Conclusions: Based on data currently available, it appears that beginning intravenous heparin during the first hour of the tPA infusion and continuing heparin for 24 hours appears most appropriate and has a minimal risk of bleeding. Delaying heparin for 9–12 hours after the streptokinase infusion appears to produce clinical benefits; however, it is not clear whether these benefits outweigh the potential risks of bleeding.