Most patients with coronary artery disease receive aspirin for primary or secondary prevention of myocardial infarction, stroke, and death. Aspirin poses a risk of bleeding in patients undergoing surgery, but it is unclear whether aspirin should be stopped before coronary artery surgery. Myles et al. used a 2-by-2 factorial trial design to randomly assign patients who were scheduled to undergo coronary artery surgery and were at risk for perioperative complications to receive aspirin or placebo and tranexamic acid or placebo. One aim of their ongoing trial was to determine whether aspirin would reduce the occurrence of death and thrombotic complications in at-risk patients who were undergoing coronary artery surgery. The results of the aspirin trial are reported in the February 25, 2016, issue of the New England Journal of Medicine.
In a randomized trial involving 2100 patients undergoing coronary-artery surgery, the risk of bleeding within 30 days after surgery was not higher with aspirin than with placebo, nor was the risk of death or thrombosis within 30 days after surgery lower with aspirin than with placebo. A new Review Article summarizes.
Clinical Pearl
• What has been the traditional practice with respect to stopping or continuing aspirin prior to coronary artery surgery?
Until recently, it has been traditional practice in most cardiac surgical centers to have patients stop taking aspirin 5 to 7 days before surgery to reduce the risk of bleeding. Aspirin is routinely recommenced within 24 hours after coronary artery bypass grafting (CABG) surgery, but this practice does not allow for the use of aspirin to help prevent thrombosis in the crucial early postoperative phase. Several observational studies have shown reductions in mortality, the rate of serious complications, or both when aspirin is administered preoperatively or soon after CABG surgery. Conflicting guidelines from expert professional organizations highlight the dearth of data from large clinical trials and the lack of reliable recommendations.
Clinical Pearl
• Are there any studies suggesting that the withdrawal of aspirin in patients scheduled for coronary artery surgery could be harmful?
The withdrawal of aspirin to reduce the risk of bleeding in patients scheduled for surgery could be harmful. The most recent meta-analysis that evaluated the use of aspirin in patients undergoing CABG surgery included 13 randomized trials with a total of 2399 participants. The authors found that the continuation of aspirin reduced the risk of perioperative myocardial infarction by nearly half. However, there was evidence of increased bleeding, increased need for red-cell transfusions, and a need for surgical reexploration.
Morning Report Questions
Q: Does the preoperative use of aspirin reduce the incidence of death or thrombotic complications, or surgical bleeding, in at-risk patients undergoing coronary artery surgery?
A: In the trial by Myles et al., the use of preoperative aspirin before coronary artery surgery resulted in neither a lower risk of death or thrombotic complications than that with placebo nor a higher risk of surgical bleeding, need for transfusion, or need for reoperation. The authors concluded that there is therefore no reason to discontinue aspirin before coronary artery surgery. Death or thrombotic complications occurred within the first 30 days after surgery in 202 patients (19.3%) in the aspirin group and in 215 patients (20.4%) in the placebo group (relative risk with aspirin, 0.94; 95% CI, 0.80 to 1.12; P=0.55). Myocardial infarction was detected within the first 30 days after surgery in 144 patients (13.8%) in the aspirin group and in 166 patients (15.8%) in the placebo group (relative risk, 0.87; 95% CI, 0.71 to 1.07; P=0.20). The rates of death, stroke, pulmonary embolism, renal failure, and bowel infarction were similar in the two groups. Major hemorrhage leading to reoperation occurred in 1.8% of patients in the aspirin group and in 2.1% of patients in the placebo group (P=0.75), and cardiac tamponade occurred in 1.1% and 0.4%, respectively (P=0.08).
Table 2. Outcomes.
Table 3. Hemostasis, Blood Loss, and Adverse Events.
Q: In the Myles study, was there a significant interaction between aspirin and tranexamic acid?
A: There was no significant interaction between the effects of aspirin and tranexamic acid with regard to the primary end point or major hemorrhage (P>0.05 for each interaction).