[Mechanism of thrombosis: physiopathology, role of thrombin and its inhibition by modern therapies].

Although the number of cardiological interventional procedures is in constant progression, they still carry a considerable risk of thrombotic complications. The different antithrombotic strategies in force reduce their incidence but at the price of an excess of bleeding complications. In order to improve the benefit/risk ratio, new antithrombotic drugs have been developed. The thrombin antagonists have a choice role because, in addition to its effect of fibrinogen, thrombin plays a fundamental part in the initiation and maintenance of the thrombosis, both by activating the clotting factors and by stimulating the platelets. Unfractionated heparin was the thrombin inhibitor of choice for many years in interventional cardiology but the improvement of our knowledge of the mechanisms of thrombosis has helped define its limitations. Direct inhibitors of thrombin such as bivalirudine avoid most of these disadvantages. One of their main advantages is their efficacy within the constituted clot itself, whereas heparin, in the absence of antithrombin, has a deleterious effect. The reversibility of the effect of bivalirudine probably plays a role in maintaining the haemostatic equilibrium providing an antithrombotic effect at least as effective as that of heparin but with a reduced risk of bleeding and without any specific biological surveillance. These advantages have been confirmed in the initial clinical trials but further studies aim t widen their application to patients selected with a higher risk of thrombotic events.