Failure of Antiplatelet and Anticoagulant Therapy to Improve Patency of Grafts after Coronary-Artery Bypass: A Controlled, Randomized Study

Fifty patients who underwent aortocoronary saphenous-vein bypass-graft surgery were randomly assigned to one of three groups to determine the effects of antiplatelet or anticoagulant therapy on graft patency. Twenty-four patients served as controls; 13 patients received aspirin (325 mg three times a day) and dipyridamole (75 mg three times a day); and 13 patients received closely regulated warfarin therapy. Medications were begun on the third post-operative day. Six months after surgery, all patients underwent coronary angiography to assess graft patency. There were no statistically significant differences between groups in various clinical, hemodynamic and angiographic findings. Vein-graft patency was 50 of 61 grafts (82 per cent) in controls, 27 of 33 grafts (82 per cent) with aspirin and dipyridamole and 29 of 37 grafts (78 per cent) with warfarin (P<0.5). All patients had at least one patent graft. Postoperative treatment either with aspirin and dipyridamole or with warfarin failed to improve the patency of the grafts. (N Engl J Med 301:962–966, 1979) CORONARY-ARTERY bypass reduces chest pain and increases exercise capacity in patients with coronary-artery disease.^{1 2 3} If grafts are occluded, these benefits may not occur^{4 5 6}; therefore, maintenance of graft patency is essential. The reported incidence of graft patency is related to the length of time after operation that the grafts were evaluated. The patency rate ranged from 89 per cent at two weeks to 65 to 85 per cent one or more years later.^{1 2 3,7 8 9 10 11} Previously reported results from our institution showed 81 per cent of 320 grafts patent within seven months.⁹ In general, most graft occlusions are thought to occur some.