LOW-MOLECULAR-WEIGHT HEPARINS FOR ACUTE CORONARY SYNDROMES

OBJECTIVE: TO review published literature regarding the use of low-mol ecular-weight heparins (LMWHs) for the acute coronary syndromes of uns table angina and acute myocardial infarction (MI). METHODS: A MEDLINE search (January 1986-August 1997) was performed to identify all pertin ent articles. Selected references from these articles and abstracts of recent clinical trials were also included, DISCUSSION: LMWHs have sev eral distinct advantages over standard unfractionated heparin (UFH). T hese advantages include convenient once-or twice-daily standardized ad ministration without the need for activated partial thromboplastin tim e monitoring. While the use of LMWHs as prophylaxis and treatment of v enous thromboembolism is fairly well-established, the use of LMWHs for treating acute myocardial ischemia is evolving. Published studies and abstracts have shown LMWHs to be as effective as or more effective th an UFH in preventing death, myocardial infarction, and recurrent ische mia in patients with unstable angina or acute MI. The comparative inci dence of bleeding between LMWHs and UFH is controversial, with some st udies reporting lower or similar rates of bleeding with LMWHs, while o ne study demonstrated a higher bleeding rate than with UFH. The cost-e ffectiveness of using LMWHs over UFH for acute coronary syndromes also remains to be established CONCLUSIONS: LMWHs appear to be as effectiv e as, and potentially more effective than, UFH in preventing complicat ions of acute coronary syndromes. However, further studies are needed to better define the comparative bleeding risks of LMWHs and UFH. This , plus the lack of published peer-reviewed trial results and pharmacoe conomic analyses, preclude the recommendation of routinely using LMWHs for treating unstable angina and acute MI at this time.