Long-term management of patients after venous thromboembolism.

Long-term treatment of venous thromboembolism (VTE) focuses mainly on the duration of anticoagulant therapy, usually with vitamin K (VK) antagonists. The duration of therapy should be individualized based on the risk of recurrent VTE if treatment were stopped and the risk of bleeding if treatment were continued. The risk of recurrence is low if thrombosis was provoked by a major reversible risk factor such as surgery; 3 months of treatment is usually adequate for such patients. The risk of recurrence is high if thrombosis was unprovoked ("idiopathic") or associated with an irreversible risk factor such as cancer; anticoagulant treatment for at least 6 months, and often indefinitely, is indicated for such patients. Risk of recurrence is intermediate if thrombosis was associated with a minor transient risk factor; such patients can be treated for 3 to 6 months. Within each of these categories, presentation as pulmonary embolism, >1 previous VTE, an underlying malignancy, an antiphospholipid antibody, or selected hereditary thrombophilic states favor more prolonged therapy, whereas isolated distal deep vein thrombosis, high risk of bleeding, and patient preference favor shorter treatment. The optimal intensity of anticoagulant therapy with VK antagonists corresponds to a target international normalized ratio of 2.5 (range, 2.0 to 3.0). Long-term treatment with low-molecular-weight heparin is an alternative to VK-antagonist therapy and is usually preferable in patients with active cancer. Oral direct thrombin inhibitors also appear suitable for long-term prevention of recurrent VTE but await regulatory approval and comparison with VK antagonists.