Clinical use of enoxaparin in the management of non-ST segment elevation acute coronary syndromes

Enoxaparin (Lovenox (R); Roule-Poulenc Rorer, Inc.), a low molecular weight heparin (LMWH), is commonly used in the management of non-ST-segment elevation acute coronary syndromes (NSTE ACS) based on clinical trial outcomes. It is one of a group of glycosaminoglycan compounds that accelerate the inactivation of factor Xa by inducing a conformational change in antithrombin. In contrast to unfractionated heparin (UFH), LMWH have greater bioavailability, a more predictable anticoagulant response, longer half-life and a higher proportion of anti-factor Xa to anti-factor IIa activity. As a consequence, laboratory monitoring of the anticoagulant effect is typically unnecessary. Antithrombin therapy with LMWH or UFH has the highest-level recommendation (IA) in the 2002 professional guidelines for the management of unstable angina and non-ST-elevation myocardial infarction, where enoxaparin has a IIA recommendation over UFH unless early coronary artery bypass surgery is planned. In a recent systematic overview of > 20,000 patients with NSTE ACS from six clinical trials, including conservative and invasively managed patients, enoxaparin provided a statistically significant reduction in 30-day death or nonfatal myocardial infarction (MI) compared with UFH with no significant excess in transfusions, or major bleeding. These data support the role of enoxaparin as an anticoagulant in patients with NSTE ACS.