title: Impact of CYP2C19 polymorphism and smoking on response to clopidogrel in patients with stable coronary artery disease.
abstract: BACKGROUND
  Dual anti-platelet treatment with aspirin and clopidogrel is established foundation for patients undergoing percutaneous coronary intervention (PCI) to prevent thrombotic events. The present study was conducted to examine whether the CYP2C19 681G > A polymorphism and cigarette smoking had independent or interactive effect on response to clopidogrel.
  
  
  METHODS
  Among 722 Chinese Han patients undergoing elective coronary stent placement due to stable angina pectoris, a loading dose of 300 mg clopidogrel was given to all patients and a daily maintenance dose of 75 mg for a minimum of 12 months. CYP2C19 681G > A polymorphism was genotyped. The platelet reactivity was measured by light transmittance aggregometry (LTA) with 5 µmol/L adenosine diphosphate (ADP) induced. The poor response was defined as 10% or less absolute difference between aggregation at baseline and 24 hours after loading dose of clopidogrel.
  
  
  RESULTS
  The results showed that the poor-response to clopidogrel was presented in 105 patients (14.5%). Overall, the genotype GA/AA carriers were likely to be poor-responsive cases (19.6% vs. 11.0%, P = 0.001) with odds ratio (OR) of 1.971 (95%CI: 1.296 - 2.998, P = 0.002), compared with the GG homozygotes. Meanwhile, compared with nonsmokers, the smokers showed lower rate of poor-response (10.9% vs. 17.3%, P = 0.015) with OR of 0.582 (95%CI: 0.374 - 0.904, P = 0.016). The smokers with GG genotype had the lowest risk with OR of 0.487 (95%CI: 0.246 - 0.961, P = 0.038) while nonsmokers with GA/AA genotype had the highest risk of poor-response with OR of 1.823 (95%CI: 1.083 - 3.068, P = 0.024), compared with nonsmokers with GG genotype. However, there was no significant interaction between genotype and smoking.
  
  
  CONCLUSIONS
  Our study indicated that both CYP2C19 polymorphism and smoking independently affected response to clopidogrel.
authors.affiliation: Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China.
authors.forename: Xiao-Li
authors.initials: XL
authors.lastname: Liu
authors.forename: Zhi-Jian
authors.initials: ZJ
authors.lastname: Wang
authors.forename: Qing
authors.initials: Q
authors.lastname: Yang
authors.forename: Hai-Long
authors.initials: HL
authors.lastname: Ge
authors.forename: Fei
authors.initials: F
authors.lastname: Gao
authors.forename: Yu-Yang
authors.initials: YY
authors.lastname: Liu
authors.forename: Dong-Mei
authors.initials: DM
authors.lastname: Shi
authors.forename: Ying-Xin
authors.initials: YX
authors.lastname: Zhao
authors.forename: Yu-Jie
authors.initials: YJ
authors.lastname: Zhou
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D000077144:Clopidogrel; D003324:Coronary Artery Disease / Q000235:genetics* / Q000628:therapy*; D065731:Cytochrome P-450 CYP2C19; D054855:Drug-Eluting Stents; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use; D011110:Polymorphism, Genetic / Q000235:genetics*; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000627:therapeutic use
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19; D013988:Ticlopidine