title: Prevalence of high platelet reactivity in aspirin-treated patients referred for coronary angiography.
abstract: BACKGROUND
  Aspirin (ASA) reduces adverse events in coronary artery disease (CAD) patients by inhibiting platelets. Some CAD patients have high platelet reactivity (HPR) despite ASA therapy and these individuals have increased risk of adverse events.
  
  
  OBJECTIVE
  The purpose of this study was to determine the prevalence of HPR in ASA-treated patients referred for coronary angiography and to assess whether the HPR correlates with the severity of CAD.
  
  
  METHODS
  This single center investigation enrolled 115 consecutive ASA-treated patients with stable CAD. ADP- and collagen-induced platelet reactivity were evaluated by light transmittance aggregometry (LTA). Patients with greater than 70% ADP- and collagen-induced aggregation were determined to have HPR and, in this group, ASA compliance was assessed by examining blood salicylate levels. Mean age was 60.9 years and average ASA dose was 164.2 mg.
  
  
  RESULTS
  Smoking and DM were present in 28.7% and 31.5% respectively. HPR was found in 14 patients (13%) however 7 of the 14 patients (50%) with HPR had low serum salicylate levels (< 2.0 µg/mL) suggesting medication noncompliance. Of the entire cohort, 6.5% of patients had HPR and detectable serum salicylate levels suggesting reduced ASA efficacy. HPR correlated with number and severity of coronary stenosis (p = 0.04).
  
  
  CONCLUSIONS
  In a general population of ASA-treated patients referred for coronary angiography, elevated platelet reactivity is prevalent (13%) with 50% related to noncompliance and 50% related to reduced aspirin efficacy.
authors.affiliation: Instituto de Cardiologia do Rio Grande do Sul, Fundação Universitária de Cardiologia, Porto Alegre, RS, Brasil. andrelmanica@yahoo.com.br
authors.forename: André
authors.initials: A
authors.lastname: Manica
authors.forename: Rogério
authors.initials: R
authors.lastname: Sarmento-Leite
authors.forename: Clara
authors.initials: C
authors.lastname: Manfroi
authors.forename: La Hore
authors.initials: LH
authors.lastname: Rodrigues
authors.forename: Carlos
authors.initials: C
authors.lastname: Gottschall
authors.forename: Julio F
authors.initials: JF
authors.lastname: Marchini
authors.forename: Kevin
authors.initials: K
authors.lastname: Croce
mesh_terms: D000368:Aged; D001241:Aspirin / Q000008:administration & dosage*; D003094:Collagen / Q000097:blood; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000150:complications / Q000188:drug therapy*; D004351:Drug Resistance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D012307:Risk Factors; D012459:Salicylates / Q000097:blood
chemical_list: D010975:Platelet Aggregation Inhibitors; D012459:Salicylates; D003094:Collagen; D001241:Aspirin