[Duration of antivitamin K therapy in venous thromboembolic disease].

The necessity for anticoagulant treatment after pulmonary embolism or deep vein thrombosis has been demonstrated. The modalities of this treatment have been established, especially the value of initial heparin relayed by oral antivitamin K therapy with a target INR value between 2 and 3. The last question remaining in this protocol is that of the duration of anticoagulant treatment. The choice of duration of anticoagulation should take into consideration two potential complications: haemorrhage due to over-anticoagulation and excessive duration of therapy, and recurrent thromboembolism which could result from an inadequate duration of therapy. Several trials have addressed this question and have led to a consensus of opinion: therefore, secondary venous thrombo-embolic disease, occurring under known, special circumstances, the cause of which has been treated, should be given 4 to 6 weeks anticoagulant therapy. In the other cases, so-called idiopathic venous thromboembolism (the proportion of which is on the increase), recent studies are inadequate to reach a consensus. These "idiopathic" forms are characterised by a higher incidence of recurrent thromboembolism of "secondary" cancer and coagulation abnormalities. The search for the optimal duration of anticoagulant therapy in these forms requires prospective trials taking their features into account and should lead to further therapeutic options. The evaluation of longer treatment protocols with less intensive degrees of anticoagulation and of alternatives to oral vitamin K antagonists is justified.