Prevention of Recurrent Pulmonary Emboli with Anticoagulants

Of 704 patients with pulmonary thromboembolism seen over a ten-year period, 443 received oral anticoagulants for an average period of 26.8 weeks. During therapy, 30 pulmonary emboli recurred in 24 (5.4 per cent) patients. Four (0.9 per cent) were fatal. Therapy was judged adequate if the Quick one-stage prothrombin time was greater than 1.6 times the control value. At the time of, or just prior to, the recurrent pulmonary embolism prothrombin times were adequate in six cases, indeterminate in three, and inadequate in 21. Pulmonary emboli recurred in 46 (10.4 per cent) of the 443 patients an average of 19.2 months after anticoagulant therapy was terminated. Five (1.1 per cent) patients died. Hemorrhage requiring transfusions and/or anticoagulant termination occurred in ten (2.2 per cent) patients; three patients (0.7 per cent) died.