Advancing Antithrombin Therapy in Acute Myocardial Infarction Management: Low Molecular Weight Heparins Plus Fibrinolysis.

Unfractionated heparin (UFH) has been traditionally used as an antithrombotic agent following fibrinolytic therapy for acute myocardial infarction. However, UFH has pharmacokinetic, biophysical, and biological limitations. Although early infarct artery patency has been superior with UFH as compared with placebo, aggregate data has demonstrated only a modest reduction in clinical events. Low molecular weight heparins (LMWHs) are attractive as potential adjunctive therapy to thrombolysis because of their greater bioavailabilty and ease of administration compared with UFH. Initial small trials with LMWHs have demonstrated their apparent safety when used in combination with thrombolytic agents, and a trend toward higher infarct-related artery patency rates. The clinical efficacy of LMWHs compared with UFH is currently being addressed in large-scale randomized clinical trials.