title: Clinical relevance of clopidogrel unresponsiveness during elective coronary stenting: experience with the point-of-care platelet function assay-100 C/ADP.
abstract: BACKGROUND
  Early identification of nonresponders to clopidogrel may be important in identifying subgroups of patients that might be at risk for future thrombotic events.
  
  
  METHODS
  We prospectively assessed postclopidogrel platelet reactivity in 250 consecutive patients scheduled for elective percutaneous coronary intervention (PCI). All patients received dual antiplatelet therapy with 160 mg aspirin and a 300 mg loading dose of clopidogrel >12 hours before PCI. A platelet aggregation test was performed at the time of the intervention using a point-of-care assay, the Platelet Function Assay (PFA-100C/ADP; Dade-Behring, Deerfield, IL). Nonresponders were defined as having a PFA closure time of <71 seconds under dual oral antiplatelet therapy, reflecting normal platelet reactivity. Myonecrosis post-PCI constituted the primary end point and was defined as the release of creatine kinase-MB >1x the upper limit of normal on a sample taken 12 to 24 hours after intervention. The secondary end point was a composite end point of major adverse cardiac events including death, myocardial infarction, and stent thrombosis after 6 months.
  
  
  RESULTS
  The PFA closure time was available in 242 patients and ranged from 31 to 300 seconds with a mean value of 147 seconds. Nonresponders represented 7% (17/242) of the cases. Myonecrosis post-PCI occurred in 29 patients (12%) and was more common in nonresponders than in normal responders (29% vs 11%, respectively; P = .03 on multivariate analysis). Major adverse cardiac events at 6 months occurred in 13 patients (1 sudden death possibly related to stent thrombosis and 12 post-PCI myocardial infarctions) and were more common in the nonresponder group (12% vs 5%, respectively; P = .06 on multivariate analysis).
  
  
  CONCLUSIONS
  Unresponsiveness to clopidogrel as assessed by the point-of-care test PFA-100C/ADP is an independent major risk factor for thrombotic complications after coronary intervention.
authors.affiliation: Department of Cardiology, University Hospital of Antwerp, Edegem, Belgium.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Moerenhout
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Claeys
authors.forename: Steven
authors.initials: S
authors.lastname: Haine
authors.forename: Hielko
authors.initials: H
authors.lastname: Miljoen
authors.forename: Johan M
authors.initials: JM
authors.lastname: Bosmans
authors.forename: Francine
authors.initials: F
authors.lastname: Vertessen
authors.forename: Katrien
authors.initials: K
authors.lastname: Kluppels
authors.forename: Marc
authors.initials: M
authors.lastname: Van der Planken
authors.forename: Christiaan J
authors.initials: CJ
authors.lastname: Vrints
mesh_terms: D000284:Administration, Oral; D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects; D001241:Aspirin / Q000008:administration & dosage; D000077144:Clopidogrel; D003331:Coronary Vessels; D016757:Death, Sudden, Cardiac / Q000209:etiology; D004351:Drug Resistance; D004359:Drug Therapy, Combination; D006801:Humans; D009203:Myocardial Infarction / Q000209:etiology; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D010979:Platelet Function Tests; D019095:Point-of-Care Systems; D011237:Predictive Value of Tests; D011300:Preoperative Care; D011446:Prospective Studies; D012307:Risk Factors; D015607:Stents / Q000009:adverse effects*; D013927:Thrombosis / Q000209:etiology*; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D013997:Time Factors
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin