[Thromboembolic complications in patients with prostheses]

By their frequency and their gravity thrombo-embolic accidents (TEA) represent the principal complication provoked by prosthetic valves. They rarely manifest themselves by an occlusive thrombosis of the valve but more usually by systemic embolisms, particularly neurological, which entail sequelae or death in more than a third of the patients. These embolisms are recurrent in one case in three. Several factors which favour TEAs are the mitral position of the valve, its mechanical nature, embolisms being rarer and less severe and occlusive thromboses exceptional with bioprostheses, and the imperfect quality of anticoagulant treatment. This last factor introduces an additional risk at least as serious as the TE risk (1 to 6 percent of patients/year with severe haemorrhage). The prevention of TEAs depends on the type of treatment with antivitamins K (AVK) and possibly on the combination of AVK--anti-aggregating agents. The best means of prevention lies in the rational choice of the prosthesis in each individual case. It is beyond question that the frequency of TEAs with mechanical valves in the mitral position and the requirement for anti-coagulant treatment entailing its own risks encourage extension of the indications for biological valves.