A systematic review 1 including 14 studies with a total of 5,779 subjects was abstracted in DARE. Two trials found that aspirin, started within one day of CABG, had a beneficial effect on graft occlusion at 12 months. Six trials, one starting aspirin pre-operatively, four between 2 and 5 days, and one at one year post-operatively, found no significant difference in graft occlusion. Two trials looked at cardiovascular events and found no significant difference in the incidence of angina, MI or death between the placebo- and aspirin-treated groups. With antilipemic agents, there was a significant reduction in the progress of atherosclerosis with antilipid agents. Subsequent cardiovascular events were not significantly reduced at the 4-year follow-up, but were at the 7-year follow-up (1 trial). With beta-blockers, at 2 years there was no difference in exercise test capacity between the groups. However, those taking placebo were found to have a higher (worse) chest pain score. None of the end points of repeat revascularisation, unstable angina, MI or death were found to be significantly different. ACE inhibitors(1 trial, 149 participants): there were no differences in exercise testing between the two groups. However, quinapril appeared to improve the incidence of ischaemic events (angina, death, MI revascularisation, stroke or transient ischaemic attacks) at one year; the event rate was 3.5% in the quinapril group and 15% in the placebo group (P=0.02).
Comment: The quality of evidence is downgraded by imprecise results (limited study size for some of the comparisons).
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