Low-Molecular-Weight Heparins in the Treatment of Acute Coronary Syndromes

Platelet aggregation and activation of coagulation are key events in the development of acute coronary syndromes. Patients with an acute coronary syndrome are at high risk of death or myocardial infarction, and hence there is a strong rationale for the use of antithrombotic agents. Heparin has been shown to reduce the risk of death or myocardial infarction in aspirin-treated patients with acute coronary syndromes, but it has a number of limitations, including the need for regular monitoring and the risk of hemorrhage and thrombocytopenia. Low-molecular-weight heparins offer a number of practical and clinical advantages over unfractionated heparin, such as higher bioavailability and administration by subcutaneous injection. Several low-molecular-weight heparins are available that differ in their biochemical and pharmacologic properties, and it is not possible to predict their clinical efficacy from their pharmacologic profile. The decision regarding the use of a specific low-molecular-weight heparin should be based on the efficacy and safety data available for each product. In clinical trials comparing low-molecular-weight heparin with heparin, only enoxaparin sodium has been shown to reduce the risk of coronary events in patients with non-ST segment elevation acute coronary ischemia.