title: High on-thienopyridine platelet reactivity in elderly coronary patients: the SENIOR-PLATELET study.
abstract: OBJECTIVE
  The aim of this study was to compare on-thienopyridine platelet reactivity of elderly patients (≥75 years) vs. younger patients (<75 years). Elderly patients represent a growing and challenging segment of the coronary population for whom the effect of dual antiplatelet therapy on platelet inhibition has not been specifically addressed.
  
  
  RESULTS
  The SENIOR-PLATELET study included 1331 coronary patients chronically (>14 days) treated with aspirin and a thienopyridine (clopidogrel 75 mg, n= 1027; clopidogrel 150 mg, n= 139; or prasugrel 10 mg, n= 165). Platelet response to clopidogrel and prasugrel was assessed by the VerifyNow assay and light transmission aggregrometry (LTA). Response to treatment, rate of high platelet reactivity (HPR), and inhibition (HPI) were compared in the two age categories. On-treatment platelet reactivity with clopidogrel 75 mg, 150 mg or prasugrel 10 mg was higher in elderly patients (n= 205) than in younger patients (n= 1126) whichever the test used. The difference in P2Y(12) reaction units (PRU) between the two populations was +45 in patients treated with clopidogrel 75 mg (P< 0.0001), +30 in patients treated with clopidogrel 150 mg (P= 0.17), and +20 with prasugrel 10 mg (P= 0.10). Differences in residual platelet aggregation were consistent when measured by LTA. Elderly patients treated with clopidogrel 75 mg were more likely to have HPR than younger patients (38.2 vs. 18.2%, OR: 2.58, 95% CI: 1.76-3.79; P< 0.0001) even after adjustment for potential confounders (adj OR: 1.83, 95% CI: 1.16-2.87; P= 0.009).
  
  
  CONCLUSIONS
  Elderly patients present an impaired response to clopidogrel with a high rate of HPR. Clopidogrel 150 mg or prasugrel 10 mg blunt, but do not eliminate the difference in response observed between old and young patients.
authors: Bureau 236, Institut de Cardiologie, INSERM UMRS937, Pitié-Salpêtrière Hospital (AP-HP), Université Paris 6, 47-83 boulevard de l'Hôpital, Paris, France.
authors: Johanne
authors: J
authors: Silvain
authors: Guillaume
authors: G
authors: Cayla
authors: Jean-Sébastien
authors: JS
authors: Hulot
authors: Jonathan
authors: J
authors: Finzi
authors: Mathieu
authors: M
authors: Kerneis
authors: Stephen A
authors: SA
authors: O'Connor
authors: Anne
authors: A
authors: Bellemain-Appaix
authors: Olivier
authors: O
authors: Barthélémy
authors: Farzin
authors: F
authors: Beygui
authors: Jean-Philippe
authors: JP
authors: Collet
authors: Gilles
authors: G
authors: Montalescot
mesh_terms: D054058:Acute Coronary Syndrome / Q000188:drug therapy*; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000077144:Clopidogrel; D003430:Cross-Sectional Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000188:drug therapy*; D010879:Piperazines / Q000008:administration & dosage*; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D000068799:Prasugrel Hydrochloride; D011446:Prospective Studies; D013876:Thiophenes / Q000008:administration & dosage*; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives*
chemical_list: D010879:Piperazines; D010975:Platelet Aggregation Inhibitors; D013876:Thiophenes; D000077144:Clopidogrel; D000068799:Prasugrel Hydrochloride; D013988:Ticlopidine