Low molecular weight heparins and coronary artery disease.

Coronary artery disease encompasses a wide spectrum of conditions including silent ischemia, exertional angina, unstable angina, and myocardial infarction. Acute coronary syndromes (unstable angina and myocardial infarction) are caused by the rupture of an atherosclerotic plaque, platelet activation, and fibrin deposition resulting in thrombosis. Aspirin and unfractionated heparin (UFH) have traditionally been the treatment of choice in patients with acute coronary syndromes; however, low molecular weight heparins (LMWHs) offer potential advantages over UFH. Available evidence indicates that LMWH is superior to UFH in reducing ischemic events or death in the acute phase of unstable angina or non-Q-wave myocardial infarction. Long-term therapy with lower doses of LMWH may not offer any advantage to aspirin in the prevention of coronary events or death. Major bleeding complications are similar for LMWH and UFH although minor bleeding complications are more common with LMWH, primarily due to injection-site hematomas. Finally, use of LMWH appears to be cost- effective compared with UFH. The available evidence supports improved clinical outcomes, favorable safety profile, and cost savings associated with LMWH use in the management of unstable angina and non-Q-wave myocardial infarction and should be favored over UFH.