Hirudin in acute coronary syndromes

Acute coronary syndromes are a major cause of morbidity and mortality in Western societies. The term describes a spectrum from unstable angina, the recently defined non-Q wave infarction (the Non ST-Elevation Myocardial Infarction [NSTEMI]), to acute transmural myocardial infarction. With regard to treatment, a series of recently published studies compared the specific direct thrombin inhibitor hirudin with standard unfractionated heparin. Initial small studies showed promising results and led to the initiation of large-scale clinical trials addressing patients with acute coronary syndromes. However, in these studies, an unacceptably high incidence of serious hemorrhagic complications prompted safety boards to stop trials. In those studies carried out according to the protocol, no significant clinical benefit of hirudin over standard heparin was proved. Here, hirudin has been shown to be equivalent to unfractionated heparin for the treatment of unstable coronary syndromes with or without ST elevation and as an adjunct to percutaneous coronary balloon angioplasty. Because of its narrow therapeutic window between clinical benefit and increased bleeding hazards, hirudin should be used cautiously. For patients with heparin-induced thrombocytopenia, hirudin is accepted as an important therapeutic alternative.