Aspirin resistance in patients with stable coronary artery disease with and without a history of myocardial infarction.
BACKGROUND
Aspirin therapy is a cornerstone in the prevention of atherothrombotic events, but recurrent vascular events are estimated to occur in 8-18% of patients taking aspirin for secondary prevention after 2 years. Estimates of biologic aspirin resistance vary from 5% to 60%, depending on the assay used. However, the relationship between biologic measurements of aspirin resistance and adverse clinical events remains unclear.


OBJECTIVE
To determine whether patients with documented myocardial infarction (MI) while on aspirin therapy (cases) were more likely to be aspirin resistant than were patients with coronary artery disease (CAD) who had no history of MI (controls) and to assess clinical predictors of aspirin resistance in patients with stable CAD.


METHODS
This case-control study examined aspirin responses using the VerifyNow Aspirin Assay system in 50 cases and 50 controls who had taken a dose of aspirin within 48 hours of presentation to the clinic visit. Odds ratios were estimated to determine the association between aspirin resistance and MI. Independent predictors of aspirin resistance were determined using univariate and multivariate analyses.


RESULTS
An increase in the prevalence of aspirin resistance among cases (16% vs 12% in controls) was not observed (OR 1.40; 95% CI 0.45 to 4.37; p = 0.566). In the overall CAD population, female sex was independently associated with aspirin resistance (OR 4.01; 95% CI 1.15 to 13.92; p = 0.029).


CONCLUSIONS
Additional large studies are required to understand whether biologically defined aspirin resistance is associated with increased risk for cardiovascular events, with special attention paid to sex differences.
Dorsch
Michael P
MP
Department of Pharmacy Services, University of Michigan Hospitals and Health Centers, Ann Arbor, MI, USA.
Lee
Jin Sun
JS
Lynch
Donald R
DR
Dunn
Steven P
SP
Rodgers
Jo E
JE
Schwartz
Todd
T
Colby
Emily
E
Montague
Debbie
D
Smyth
Susan S
SS
D000368:Aged; D001241:Aspirin / Q000627:therapeutic use*; D016022:Case-Control Studies; D003324:Coronary Artery Disease / Q000188:drug therapy / Q000453:epidemiology*; D004351:Drug Resistance; D005260:Female; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000453:epidemiology*; D016017:Odds Ratio; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D012737:Sex Factors
D010975:Platelet Aggregation Inhibitors; D001241:Aspirin