Recurrence of venous thromboembolism and its prevention

The risk of recurrent venous thromboembolism (VTE) approaches 40% in all patients after 10 years of follow-up. This risk is higher in patients with permanent risk factors for thrombosis, such as active cancer, prolonged immobilization because of disease, and antiphospholipid antibody syndrome; in patients with idiopathic presentation; and in carriers of several thrombophilic abnormalities, including carriers of AT, protein C or S, increased factor VIII, hyperhomocysteinemia, homozygous carriers of factor V Leiden or prothrombin G20210A variant, and carriers of multiple abnormalities. Patients with permanent risk factors for thrombosis should receive indefinite anticoagulation, consisting of subtherapeutic doses of low-molecular-weight heparin (LMWH) in cancer patients, and oral anticoagulants in all other conditions. Patients with idiopathic VTE, including carriers of thrombophilia, should receive 6 to 12 months of anticoagulation. The decision to discontinue anticoagulation after this period, or to go on with conventional or less intense warfarin treatment, should be individually tailored and balanced against the hemorrhagic risk.