title: Variation and importance of aspirin resistance in patients with known cardiovascular disease.
abstract: OBJECTIVE
  To investigate whether aspirin resistance is a persistent condition, and to evaluate if aspirin resistance affects one-year clinical outcome.
  
  
  RESULTS
  Previously we studied 298 patients admitted to hospital with symptoms suggestive of an acute myocardial infarction (MI) despite treatment with aspirin, and 70 patients (23.5%) were aspirin resistant. In the present study, platelet function was reassessed by use of a Platelet Function Analyzer-100 one year later. A total of 187 patients were re-examined, and 17 (9.1%) demonstrated aspirin resistance. Of these 17 patients, 12 also exhibited aspirin resistance at baseline resulting in a 6% (12/187) prevalence of persistent aspirin resistance. A total of 34 patients had changed from aspirin resistant at baseline to aspirin sensitive at follow-up. We found a significant decrease in the prevalence of aspirin resistance from baseline (43%) to follow-up (11%) in patients with MI at baseline (p=0.0018). Furthermore, a significant decrease was found for patients without MI at baseline (20% to 9%, p=0.0009). During follow-up, 17% (12/70) of the patients with aspirin resistance at baseline suffered death, MI or stroke compared to 16% (37/227) of aspirin sensitive patients (p=0.868).
  
  
  CONCLUSIONS
  The prevalence of aspirin resistance varies with the clinical status of the patients, and indeed an acute MI is associated with temporary aspirin resistance. We also found that 6% of patients demonstrate persistent aspirin resistance. The presence of aspirin resistance did not affect one-year clinical outcome.
authors.affiliation: Department of Cardiology, Odense University Hospital, Sdr. Boulevard 29, DK-5000 Odense C, Denmark. tina.poulsen@ouh.fyms-amt.dk
authors.forename: Tina Svenstrup
authors.initials: TS
authors.lastname: Poulsen
authors.forename: Søren Risom
authors.initials: SR
authors.lastname: Kristensen
authors.forename: Lars
authors.initials: L
authors.lastname: Korsholm
authors.forename: Torben
authors.initials: T
authors.lastname: Haghfelt
authors.forename: Bo
authors.initials: B
authors.lastname: Jørgensen
authors.forename: Peter Bjørn
authors.initials: PB
authors.lastname: Licht
authors.forename: Hans
authors.initials: H
authors.lastname: Mickley
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001241:Aspirin / Q000494:pharmacology* / Q000627:therapeutic use; D002318:Cardiovascular Diseases / Q000150:complications* / Q000188:drug therapy / Q000401:mortality; D004351:Drug Resistance; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy / Q000209:etiology; D010979:Platelet Function Tests; D015995:Prevalence; D020521:Stroke / Q000188:drug therapy / Q000209:etiology
chemical_list: D001241:Aspirin