title: Association of aspirin dosage to clinical outcomes after percutaneous coronary intervention: observations from the Ottawa Heart Institute PCI Registry.
abstract: BACKGROUND
  Dual antiplatelet therapy, with aspirin and a thienopyridine, is the accepted treatment after percutaneous coronary intervention (PCI). No clear evidence exists regarding the ideal dosage of aspirin. Recent guidelines recommend higher-dose aspirin because of the possible decrease in stent thrombosis. The purpose of this study was to test the hypothesis that high-dose aspirin of 325 mg decreases death and myocardial infarction (MI) compared to a lower dose of 81 mg in patients undergoing PCI.
  
  
  METHODS
  An observational cohort study of 1,840 consecutive patients who underwent PCI was conducted. Patients who did not survive to discharge were excluded. The primary endpoint was a composite of all-cause mortality and MI at 1 year.
  
  
  RESULTS
  Nine-hundred and thirty patients (50.5%) were discharged on 325 mg of aspirin and 910 (49.5%) were discharged of 81 mg. The risk of all-cause mortality or MI was not significantly different between patients: low-dose 5.49% (50/910) vs. high-dose 4.19% (39/930); adjusted odds ratio [OR], 1.16; 95% confidence interval [CI], 0.73-1.85). In a multivariable analysis, the Charlson comorbidity score (OR, 1.37; 95% CI, 1.18-1.58) and urgent PCI (OR, 1.75; 95% CI, 1.03-3.00) were associated with increased death or MI. Among patients with drug-eluting stents, the use of low-dose aspirin did not predispose them to death or MI (adjusted OR, 1.12, 95% CI, 0.53-2.34).
  
  
  CONCLUSIONS
  In this large contemporary analysis of PCI patients, no differences in death or MI were observed at 1 year between patients discharged on low-dose aspirin 81 mg compared to patients on a higher dose.
authors.affiliation: University of Ottawa Heart Institute, Cardiology, Ottawa, Ontario, Canada. dso@ottawaheart.ca
authors.forename: Derek
authors.initials: D
authors.lastname: So
authors.forename: E Francis
authors.initials: EF
authors.lastname: Cook
authors.forename: Michel
authors.initials: M
authors.lastname: Le May
authors.forename: Chris
authors.initials: C
authors.lastname: Glover
authors.forename: William
authors.initials: W
authors.lastname: Williams
authors.forename: Andrew
authors.initials: A
authors.lastname: Ha
authors.forename: Richard
authors.initials: R
authors.lastname: Davies
authors.forename: Michael
authors.initials: M
authors.lastname: Froeschl
authors.forename: Jean-Fran Cois
authors.initials: JF
authors.lastname: Marquis
authors.forename: Edward
authors.initials: E
authors.lastname: O'Brien
authors.forename: Marino
authors.initials: M
authors.lastname: Labinaz
mesh_terms: D015906:Angioplasty, Balloon, Coronary / Q000379:methods*; D001241:Aspirin / Q000009:adverse effects / Q000627:therapeutic use*; D002170:Canada; D003131:Combined Modality Therapy; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000628:therapy*; D006801:Humans; D016015:Logistic Models; D008297:Male; D009203:Myocardial Infarction / Q000517:prevention & control / Q000628:therapy*; D017202:Myocardial Ischemia / Q000517:prevention & control / Q000628:therapy*; D017063:Outcome Assessment, Health Care; D010351:Patient Discharge; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D011446:Prospective Studies; D012042:Registries; D012189:Retrospective Studies; D055502:Secondary Prevention
chemical_list: D010975:Platelet Aggregation Inhibitors; D001241:Aspirin