title: Profile and prevalence of aspirin resistance in patients with cardiovascular disease.
abstract: We determined the prevalence and clinical predictors of aspirin resistance by prospectively studying 325 patients with stable cardiovascular disease who were receiving aspirin (325 mg/day for > or =7 days) but no other antiplatelet agents. We also compared the detection of aspirin resistance with optical platelet aggregation, a widely accepted method, with a newer, more rapid method, the platelet function analyzer (PFA)-100, a whole blood test that measures platelet adhesion and aggregation ex vivo. Blood samples were analyzed in a blinded fashion for aspirin resistance by optical aggregation using adenosine diphosphate (ADP) and arachidonic acid, and by PFA-100 using collagen and/or epinephrine and collagen and/or ADP cartridges to measure aperture closure time. Aspirin resistance was defined as a mean aggregation of > or =70% with 10 microM ADP and a mean aggregation of > or =20% with 0.5 mg/ml arachidonic acid. Aspirin semiresponders were defined as meeting one, but not both of the above criteria. Aspirin resistance by PFA-100 was defined as having a normal collagen and/or epinephrine closure time (< or =193 seconds). By optical aggregation, 5.5% of the patients were aspirin resistant and 23.8% were aspirin semiresponders. By PFA-100, 9.5% of patients were aspirin resistant. Of the 18 patients who were aspirin resistant by aggregation, 4 were also aspirin resistant by PFA-100. Patients who were either aspirin resistant or aspirin semiresponders were more likely to be women (34.4% vs 17.3%, p = 0.001) and less likely to be smokers (0% vs 8.3%, p = 0.004) compared with aspirin-sensitive patients. There was a trend toward increased age in patients with aspirin resistance or aspirin semiresponders (65.7 vs 61.3 years, p = 0.06). There were no differences in aspirin sensitivity by race, diabetes, platelet count, renal disease, or liver disease.
authors.affiliation: Department of Cardiology, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Gum
authors.forename: K
authors.initials: K
authors.lastname: Kottke-Marchant
authors.forename: E D
authors.initials: ED
authors.lastname: Poggio
authors.forename: H
authors.initials: H
authors.lastname: Gurm
authors.forename: P A
authors.initials: PA
authors.lastname: Welsh
authors.forename: L
authors.initials: L
authors.lastname: Brooks
authors.forename: S K
authors.initials: SK
authors.lastname: Sapp
authors.forename: E J
authors.initials: EJ
authors.lastname: Topol
mesh_terms: D000328:Adult; D001241:Aspirin / Q000627:therapeutic use*; D002318:Cardiovascular Diseases / Q000097:blood*; D004351:Drug Resistance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D015995:Prevalence; D011446:Prospective Studies; D012737:Sex Factors
chemical_list: D010975:Platelet Aggregation Inhibitors; D001241:Aspirin