Safety and efficacy of warfarin started early after submassive venous thrombosis or pulmonary embolism.

Two anticoagulant regimens, similar except for the timing of warfarin therapy, were compared in patients with clinically submassive venous thromboembolism (VTE). Warfarin was begun after 7 days of continuous intravenous heparin infusion in group L (127 patients) or within 3 days (average 1 day) of starting heparin in group S (139 patients), with similar outcomes. The frequency of symptomatic VTE recurrence during the hospital stay was 4.7% in group L and 3.6% in group S, and that of symptomless new perfusion defects 8.5% in group L and 3.9% in group S. On routine iodine-125-fibrinogen leg scanning of patients presenting with distal thrombosis (in the calf, popliteal, or distal femoral veins) 3.6% of group S but no group L patients had symptomless proximal extension. The incidence of bleeding was similar with both regimens. Outpatient follow-up showed no excess recurrent VTE in either treatment group. Early warfarin treatment significantly shortened hospital stay by an average of 3.9 days (30%) in patients admitted solely because of VTE.