[Low-dose acetylsalicylic acid (100 mg/day) following aortocoronary bypass operation].

A prospective, randomized, double-blind, placebo-controlled trial was conducted to evaluate the efficacy of Acetylsalicylic Acid (ASS) (100 mg/d, starting 24 h after operation) on vein graft patency. Sixty of 88 patients having undergone surgery entered the study; in 24 of 31 patients in the placebo group and 22 of 29 patients in the ASS-group angiography was performed 4 months postoperatively. There were no significant differences between the groups with respect to age, number of diseased vessels or previous myocardial infarctions. Mean number of grafts per patient was 2,2 (placebo) and 1,8 (ASS) for proximal anastomoses (p less than 0.10) and 3.4 (placebo) and 2.6 (ASS) for distal anastomoses (p less than 0.05). Graft occlusion rate for proximal anastomoses was less in the ASS-group, 10% (4/40), as compared with placebo 32% (17/53) (p less than 0.05). Graft occlusion rate for distal anastomoses was also less in the ASS group, 19% (11/57) as compared to 35% (28/81) in the placebo group (p less than 0.10). All grafts were patent in 16/22 patients in the ASS group but only in 9/24 in the placebo group (p less than 0.05). On designation of patients without postoperative angiograms but cardiovascular events as well as those with at least one graft occluded as "failures", the incidence of the latter was 9/29 in the ASS group and 20/31 in the placebo group (p less than 0.05). Early postoperative bleeding was similar in both groups, no side effects of ASS were observed. In this trial with initiation of low - dose ASS therapy 24 h after operation, antiplatelet therapy reduced the graft occlusion rate significantly.