title: Determination of the prevalence of aspirin and clopidogrel resistances in patients with coronary artery disease by using various platelet-function tests.
abstract: BACKGROUND
  Dual therapy with aspirin and clopidogrel has emerged as the gold standard therapy for patients treated with drug-eluting stents (DES). However, there is variability in patients' responses to this antiplatelet therapy, and some patients continue to show ischemic recurrences after therapy. The purpose of the study was to compare the simultaneously obtained results of various platelet-function tests for assessing the prevalence of antiplatelet resistance in coronary artery disease patients undergoing DES therapy.
  
  
  METHODS
  A total of 66 patients were administered a loading dose of aspirin, clopidogrel, and cilostazol at least 12 hr before stenting. The results of VerifyNow (Accumetrics, USA), multiplate analyzer (Dynabyte Medical, Germany), and vasodilator-stimulated phosphoprotein/P2Y12 (Biocytex, France) assays were compared with those of light transmission aggregometry (LTA) analysis.
  
  
  RESULTS
  The P2Y12 reaction units and P2Y12% inhibition values obtained using the VerifyNow assay showed strong correlation (r) with the results of the LTA analysis. All tests results showed low concordance in defining the antiplatelet resistance in patients, and the degrees of agreement were as follows: 0 for aspirin reaction units; 0.25, P2Y12% inhibition; 0, aspirin-sensitive patients' identification test; 0.21, ADPtest; and 0.14, platelet reactivity index, expressed as the κ statistics. The prevalence of aspirin and clopidogrel resistances in patients resulted in remarkable variations, from 0% to 22.7% and from 9.1% to 48.5%, respectively.
  
  
  CONCLUSIONS
  The clinical usefulness of the different assays for the correct classification of patients in terms of antiplatelet resistance remains unclear. Further studies are required to determine the best method for correlating the occurrences of adverse ischemic events.
authors.affiliation: Department of Laboratory Medicine, Dong-A University College of Medicine, Busan, Korea.
authors.forename: Kwang-Sook
authors.initials: KS
authors.lastname: Woo
authors.forename: Bo-Ram
authors.initials: BR
authors.lastname: Kim
authors.forename: Ji-Eun
authors.initials: JE
authors.lastname: Kim
authors.forename: Ri-Young
authors.initials: RY
authors.lastname: Goh
authors.forename: Long-Hao
authors.initials: LH
authors.lastname: Yu
authors.forename: Moo-Hyun
authors.initials: MH
authors.lastname: Kim
authors.forename: Jin-Yeong
authors.initials: JY
authors.lastname: Han
mesh_terms: D000368:Aged; D001241:Aspirin / Q000008:administration & dosage*; D000077407:Cilostazol; D000077144:Clopidogrel; D003324:Coronary Artery Disease / Q000188:drug therapy*; D004351:Drug Resistance; D004359:Drug Therapy, Combination; D054855:Drug-Eluting Stents; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D010979:Platelet Function Tests; D058921:Purinergic P2Y Receptor Antagonists / Q000008:administration & dosage; D058925:Receptors, Purinergic P2Y12 / Q000378:metabolism; D013777:Tetrazoles / Q000008:administration & dosage; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives*
chemical_list: D010975:Platelet Aggregation Inhibitors; D058921:Purinergic P2Y Receptor Antagonists; D058925:Receptors, Purinergic P2Y12; D013777:Tetrazoles; D000077144:Clopidogrel; D000077407:Cilostazol; D013988:Ticlopidine; D001241:Aspirin