The effect of dipyridamole and warfarin on the patency rate of coronary artery bypass grafts.

Seventy consecutive patients who had undergone coronary artery bypass surgery were postoperatively treated with either dipyridamole or warfarin for 6 months. The dipyridamole series consisted of 28 patients given 150 mg dipyridamole 3 times daily and the warfarin series, of 42 patients who received the appropriate daily dose of warfarin needed to maintain the prothrombin time within the therapeutic range. The majority of patients in both series belonged to the NYHA class III. Sixty-one percent of the patients in the dipyridamole series and 66% of those of the warfarin series had triple vessel disease. In all, 70 and 105 coronary artery branches were bypassed in the dipyridamole and warfarin series, respectively. This resulted in 2.5 distal anastomoses per patient in each series. The patency of the grafts was confirmed angiographically. There was no mortality during the 23.6 +/- 2.4 months follow-up period in the dipyridamole series or the 12.8 +/- 2.7 months in the warfarin series. The patency rates were 95.7% and 88.6% in the dipyridamole and warfarin series, respectively. It is apparent that dipyridamole is not less effective than warfarin in preventing postoperative coronary graft occlusion.