Heparin therapy in venous thromboembolism

Patients with pulmonary embolism or deep venous thrombosis were randomly assigned to receive either intermittent or continuous intravenous heparin therapy. In patients with an enhanced risk of bleeding, major bleeding was significantly more common during the intermittent use of heparin; in patients without these risk factors, hemorrhage occurred with equal frequency during intermittent and continuous heparin therapy. Recurrent thromboembolism was seen significantly more often in patients receiving continuous heparin therapy. Controlling the dose of heparin with coagulation tests resulted in the administration of significantly larger daily doses of heparin with intermittent injections than with continuous infusion. Therefore, the bleeding complications of intermittent heparin therapy could have been due to the higher dose, and the recurrences associated with continuous heparin therapy may have resulted from lower doses rather than from differences in the method of administration. In a small trial, arbitrary lower does of heparin given intermittently similar to the doses of heparin given continuously resulted in fewer bleeding complications and more recurrences. In patients without risk factors for bleeding, the intermittent administration of heparin in the higher dose is preferable because of fewer recurrences and no increase in hemorrhagic complications. In patients with a high risk of bleeding, conventional doses of heparin given continuously can reduce the rate of hemorrhagic complications but will result in more recurrences.