Aspirin Resistance After Off-pump Coronary Artery Bypass Grafting Surgery

Background:Aspirin is an important drug proven to reduce saphenous vein graft failure, but aspirin resistance frequently occurs after off-pump coronary artery bypass grafting (OPCAB). The present study was designed to describe the incidence of aspirin resistance, and evaluate the aspirin effectiveness in the inhibition of platelet aggregation and thromboxane formation in patients after OPCAB.Methods:Three hundreds and eighty patients were enrolled in a prospective study (n = 150 for OPCAB surgery and n= 230 for non-surgery). Arachidonic acid induced platelet aggregation and urine 11-dehydro thromboxane B2 were performed in the morning before operation and after re-administered days 1,4 and 10.6 months follow-up was completed in the patients who developed aspirin resistance after bypass surgery. The sequence was drawn to analyze the association between aspirin resistance and genetic polymorphisms of GP1Ba (C1018T). PI (A1/A2), P2Y1 (A1622G) and TBXA2R (T924C).Results:ARA-induced platelet aggregation was significantly lower at all monitored postoperative times in comparison with the preoperative values (P<0.001).43 patients (30%) developed aspirin resistance on re-administered day 1 after OPCAB. On re-administered day 4 and 10.20(13.3%) and 5(3.3%) patients developed aspirin resistance, separately. Platelet aggregation was (61.9±14.5)%, (23.8±23.3)%. (14.8±13.9)%and (11.4±11.1)%. Urine 11-dehydroTxB2 decreased gradually. On re-administered day 1.4 and 10. urine 11-dehydroTxB2 was (68.1±16.2) ng/L (48.4±16.7) ng/L and (26.8±12.1) ng/L.6 months follow-up was completed in the patients who developed aspirin resistance after OPCAB. Platelet aggregation was (11.5=3.4)%. and urine 11-dehydroTxB2 was (50.3=15.4) ng/L. increased unexpectedly. Results for DNA sequencing showed polymorphisms of P2Y1 (A1622G), TBXA2R (T924C). T homozygote of TBXA2R (T924C) in the number of patients with AR was 33 cases, CT and CC genotype patients'number of patients with AR was 10 cases.Conclusions:Aspirin resistance is encountered during the early postoperative period in a certain patients undergoing OPCAB. In case of resistance, treatment would need to be tailored to the individual. Aspirin was less effective for 924T homozygote of a TXA2R, T924C. which suggesting that 924T alleles are involved in aspirin resistance.