[The importance of thrombin and its inhibition in unstable angina. Nonfractionated heparin, hirudin and defractionated heparins].

Atheroma plaque rupture with liberation of tissue factor activates the coagulation cascade and plateletes, leading to the formation of intracoronary thrombi in many patients with acute coronary syndromes. In this process, tissue factor, thrombin, Factor Xa and fibrin play a major role. This review analyses the clinical efficacy of the antithrombotic drugs: fractionated heparin, low molecular or fractionated heparins, direct thrombin inhibitors, specific Xa factor inhibitors and inhibitors of the tissue factor pathway in patients with unstable angina and non-Q wave myocardial infarction. Enoxaparin, a low molecular weight fractionated heparin, has shown to be associated with a greater clinical efficacy, superior to that achieved with conventional heparin anticoagulation or treatment with aspirin, and probably should be considered as the antithrombotic of choice. Present clinical research should be aimed at the identification of patients with greater benefit, new treatment protocols with other antithrombotic drugs and the efficacy in special situations such as invasive coronary interventions or the association with other drug like, thrombolytic agents or new antiplatelet antiaggregants.