We performed a prospective cohort trial on 220 patients undergoing elective off-pump coronary artery bypass surgery and taking aspirin to evaluate the effect of aspirin resistance on myocardial injury. The patients were divided into aspirin responders and aspirin non-responders by the value of the aspirin reaction units obtained preoperatively using the VerifyNow™ Aspirin Assay. The serum levels of troponin I were measured before surgery and 1, 6, 24, 48 and 72 hr after surgery. In-hospital major adverse cardiac and cerebrovascular events, graft occlusion, the postoperative blood loss and reexploration for bleeding were recorded. Of the 220 patients, 181 aspirin responders (82.3%) and 39 aspirin non-responders (17.7%) were defined. There were no significant differences in troponin I levels (ng/mL) between aspirin responders and aspirin non-responders: preoperative (0.04 ± 0.08 vs 0.03 ± 0.06; P = 0.56), postoperative 1 hr (0.72 ± 0.87 vs 0.86 ± 1.10; P = 0.54), 6 hr (2.92 ± 8.76 vs 1.50 ± 2.40; P = 0.94), 24 hr (4.16 ± 13.44 vs 1.25 ± 1.95; P = 0.52), 48 hr (2.15 ± 7.06 vs 0.65 ± 0.95; P = 0.64) and 72 hr (1.20 ± 4.63 vs 0.38 ± 0.56; P = 0.47). Moreover, no significant differences were observed with regard to in-hospital outcomes. In conclusion, preoperative aspirin resistance does not increase myocardial injury in patients undergoing off-pump coronary artery bypass surgery. Postoperative dual antiplatelet therapy might have protected aspirin resistant patients.
Keywords: Aspirin; Coronary Artery Bypass, Off-Pump; Drug Resistance; Hemorrhage; Troponin I.