Resistance of Acute Coronary Syndrome Patients to Antiplatelet Drugs and Its Correlation to COX-1 Gene

Objective: To investigate the responses of aspirin plus clopidogrel therapy in patients with acute coronary syndrome(ACS),and to explore the molecular biological mechanism.Methods: A total of 154 patients with ACS received dual antiplatelet drugs treatment as aspirin 100 mg/d and clopidogrel 75 mg/d.Platelet aggregation(PAG) percentage induced by arachidonic acid(AA 0.5 mmol/L) and urinary 11-dehydro-Thromboxane B2(11-DH-TXB2) was tested by ELISA method.The COX-1 gene A842G single nucleotide polymorphism was examined by PCR.Main adverse cardiac events(MACE) rates in two weeks were calculated.Results: ①Of the 154 patients with ACS,113 were acute myocardial infarction(AMI) and 41 were unstable angina pectoris(UAP),and there were significant differences in PAG induced by AA and urinary 11-DH-TXB2 before the dual antiplatelet therapy between the two groups(both P0.01);②Between the antiplatelet drugs resistance(AR) group(6 patients,3.90%) and sensitive group(AS group,148 patients,96.10%),there were significant differences in PAG induced by AA and urinary 11-DH-TXB2 after the dual antiplatelet therapy(both P0.01);③In the genotype of the COX-1 gene A842G,150 patients are AA type and 4 patients are AG type,5 of the AR group are AA type(83.33%) and one of them is AG type(16.67%),and there was a significant difference(P0.01);④The prevalence of MACE in two weeks was 33.33%(2 patients) in AR group and 4.05%(6 patients) in AS group,and there was a significant difference(P0.01).Conclusion: ①There are some extent of platelet activation in patients with ACS,presented with PAG induced by AA and the high levels of urinary 11-DH-TXB2.②There was a relationship between COX-1 gene A842G single nucleotide polymorphism and antiplatelet resistance,and the patients with mutant gene G are susceptive to AR.③The patients with AR have a higher cardiovascular event rate.