title: Cytochrome P450 2C19 polymorphism in young patients treated with clopidogrel after myocardial infarction: a cohort study.
abstract: BACKGROUND
  Clopidogrel and low-dose aspirin have become the mainstay oral antiplatelet regimen to prevent recurrent ischaemic events after acute coronary syndromes or stent placement. The frequent genetic functional variant 681 G>A (*2) of cytochrome P450 2C19 (CYP2C19) is an important contributor to the wide variability between individuals of the antiplatelet effect of clopidogrel. We assessed whether the CYP2C19*2 polymorphism affected long-term prognosis of patients who were chronically treated with clopidogrel.
  
  
  METHODS
  Between April 1, 1996, and April 1, 2008, 259 young patients (aged <45 years) who survived a first myocardial infarction and were exposed to clopidogrel treatment for at least a month, were enrolled in a multicentre registry and underwent CYP2C19*2 determination. The primary endpoint was a composite of death, myocardial infarction, and urgent coronary revascularisation occurring during exposure to clopidogrel. Follow-up was every 6 months. The key secondary endpoint was stent thrombosis proven by angiography.
  
  
  RESULTS
  Median clopidogrel exposure time was 1.07 years (IQR 0.28-3.0). Baseline characteristics were balanced between carriers (heterozygous *1/*2, n=64; homozygous *2/*2, n=9) and non-carriers (n=186) of CYP2C19*2 variant. The primary endpoint occurred more frequently in carriers than in non-carriers (15 vs 11 events; hazard ratio [HR] 3.69 [95% CI 1.69-8.05], p=0.0005), as did stent thrombosis (eight vs four events; HR 6.02 [1.81-20.04], p=0.0009). The detrimental effect of the CYP2C19*2 genetic variant persisted from 6 months after clopidogrel initiation up to the end of follow-up (HR 3.00 [1.27-7.10], p=0.009). After multivariable analysis, the CYP2C19*2 genetic variant was the only independent predictor of cardiovascular events (HR 4.04 [1.81-9.02], p=0.0006).
  
  
  CONCLUSIONS
  The CYP2C19*2 genetic variant is a major determinant of prognosis in young patients who are receiving clopidogrel treatment after myocardial infarction.
authors.affiliation: Institut de Cardiologie, INSERM 856, Université Paris 6, Hôpital Pitié-Salpêtrière (AP-HP), Paris, France.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Collet
authors.forename: Jean-Sébastien
authors.initials: JS
authors.lastname: Hulot
authors.forename: Anna
authors.initials: A
authors.lastname: Pena
authors.forename: Eric
authors.initials: E
authors.lastname: Villard
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Esteve
authors.forename: Johanne
authors.initials: J
authors.lastname: Silvain
authors.forename: Laurent
authors.initials: L
authors.lastname: Payot
authors.forename: Delphine
authors.initials: D
authors.lastname: Brugier
authors.forename: Guillaume
authors.initials: G
authors.lastname: Cayla
authors.forename: Farzin
authors.initials: F
authors.lastname: Beygui
authors.forename: Gilbert
authors.initials: G
authors.lastname: Bensimon
authors.forename: Christian
authors.initials: C
authors.lastname: Funck-Brentano
authors.forename: Gilles
authors.initials: G
authors.lastname: Montalescot
mesh_terms: D000328:Adult; D015906:Angioplasty, Balloon, Coronary; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics* / Q000502:physiology; D000077144:Clopidogrel; D065731:Cytochrome P-450 CYP2C19; D023381:Endpoint Determination; D005260:Female; D005500:Follow-Up Studies; D005838:Genotype; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000517:prevention & control* / Q000628:therapy; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D011110:Polymorphism, Genetic; D016016:Proportional Hazards Models; D012307:Risk Factors; D055502:Secondary Prevention; D015607:Stents; 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