[Improved flow through aortocoronary venous bypasses after anticoagulant therapy. A prospective randomized study].

To evaluate the effect of oral anticoagulant therapy on graft patency rate during the first 2 months after bypass surgery 174 patients were randomly assigned to treatment with phenprocoumon (89) or to a control group (85) starting on day 7 after bypass surgery. Until day 7 all patients received low dose heparin. There was no significant difference between the two groups with respect to age, sex distribution, number of vessels diseased, left ventricular enddiastolic pressure, preoperative exercise tolerance or number of grafts constructed per patient. All patients underwent angiographic evaluation 8 weeks after bypass surgery. Graft patency rate was 90.4% in the treatment group versus 83.6% in the control group (p less than 0.015). None of the grafts with a flow rate of greater than 90 ml/min was occluded 8 weeks after surgery. Oral anticoagulation improved the patency rate of grafts with a flow of less then 90 ml/min.