OVERVIEW OF RANDOMIZED TRIALS OF INTRAVENOUS HEPARIN IN PATIENTS WITHACUTE ACUTE MYOCARDIAL-INFARCTION TREATED WITH THROMBOLYTIC THERAPY

Intravenous heparin is routinely given after thrombolytic therapy for patients with acute myocardial infarction in the United States and in some, but by no means all, other countries. Several trials have docume nted improved infarct-artery patency in patients treated with heparin; however, none was forge enough individually to assess the effect of h eparin on clinical outcomes. We performed ct systematic overview of th e 6 randomized controlled trials (1,735 patients) to summarize the ava ilable data concerning the risks and benefits of intravenous heparin v ersus no heparin after thrombolytic therapy. Mortality before hospital discharge was 5.1% for patients allocated to intravenous heparin comp ared with 5.6% for controls (relative risk reduction of 9%, odds ratio 0.91, 95% confidence interval 0.59 to 1.39). Similar rates of recurre nt ischemia and reinfarction were observed among those allocated to he parin therapy or control. The rates of total stroke, intracranial hemo rrhage, and severe bleeding were similar in patients allocated to hepa rin; however, the risk of any severity of bleeding was significantly h igher (22.7% vs 16.2%; odds ratio 1.55, 95% confidence interval 1.21 t o 1.98), There was no significant difference in the observed effects o f heparin between patients receiving tissue-type plasminogen activator and those receiving streptokinase or anisoylated plasminogen streptok inase activator complex, or between patients who did and did not recei ve aspirin. The findings of this overview demonstrate that insufficien t clinical outcome data are available to support or to refute the rout ine use of intravenous heparin therapy after thrombolysis. It is not k nown if these findings are due to lack of statistical power, inappropr iate levels of anticoagulation, or lack of benefit of intravenous hepa rin. Large randomized studies of heparin (and of newer antithrombotic regimens) are needed to establish the role of such therapy.