What is the impact of preoperative aspirin administration on patients undergoing coronary artery bypass grafting?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether continuation of administration of preoperative aspirin until the day of coronary artery bypass grafting (CABG) could minimize postoperative mortality, prevalence of postoperative myocardial infarction (MI) with or without influence on postoperative bleeding, packed red blood cell (PRBC) transfusion and reoperation for bleeding. Altogether, 662 papers were found using the reported search, 7 of which represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Seven studies, included in this review, consisted of five meta-analyses and two randomized controlled trials. One meta-analysis, involving 27 533 patients submitted to CABG, showed that the administration of preoperative aspirin decreased postoperative 30-day mortality by 27%. Another meta-analysis, including 1437 patients, showed that preoperative aspirin decreased the incidence of perioperative MI by 44%, the effect being even more pronounced with low-dose aspirin, which reduced the prevalence of perioperative MI by 63%. One RCT showed that preoperative aspirin is associated with reduced long-term hazard of MI or repeated revascularization. Four meta-analyses and two RCTs showed that preoperative aspirin is associated with increased postoperative bleeding, PRBC transfusion and reoperation for bleeding. However, this was not the case with preoperative administration of low-dose aspirin. The results presented in these studies suggest that preoperative aspirin administration in patients undergoing CABG has a significant benefit in reducing the incidence of perioperative MI and 30-day mortality rate, as well as reduced long-term hazard of MI or repeated revascularization. At a higher dose (>100 mg/day), postoperative bleeding, PRBC transfusion and reoperation for bleeding increased. However, with low-dose aspirin (≤100 mg/day), these benefits were not at the expense of increased postoperative bleeding or transfusion.