Extended treatment for venous thromboembolism: how long is long enough?

The long-term aim of treatment of venous thromboembolism (VTE) is the prevention of late recurrences and the post-thrombotic syndrome. The optimal duration of oral anticoagulant therapy after VTE is still controversial. Patients are currently stratified into risk categories for recurrence on the basis of clinical characteristics of the index VTE event. Patients with distal VTE or VTE caused by a transient risk factor are at low risk for recurrence and short-term anticoagulation (3 months) is indicated. Patients with an idiopathic event or with known thrombophilic defects such as factor V Leiden or the G20210A prothrombin mutation are candidates to a longer course of therapy (6 months). Patients with cancer, antiphospholipid antibodies syndrome, recurrent idiopathic event, antithrombin deficiency, protein C or protein S deficiency, homozygosity for factor V Leiden, or double heterozygosity are candidates for extended long-term anticoagulation. More recently, studies have indicated that other factors such as D-dimer levels after the discontinuation of oral anticoagulant therapy or the residual vein thrombosis could be additional predictive factors for recurrences.