Clinical Benefit of Aspirin on Heart Attacks is Not Attributable to "Aspirin Resistance"

Charles H. Hennekens, M.D., the first Sir Richard Doll Research Professor in the Charles E. Schmidt College of Biomedical Science at Florida Atlantic University, was the first to demonstrate that aspirin prevents a first heart attack based on his landmark Physicians Health Study (PHS).

In the most recent analyses of these data, published in the May issue of the American Heart Journal, Hennekens and colleagues propose that individuals who develop a heart attack on aspirin do so, at least in part, because they are not taking the drug or they are taking non-steroidal anti-inflammatory drugs (NSAIDs) which inhibit the clinical benefit of aspirin. Previous studies had suggested that the lack of clinical benefit was due to "aspirin resistance."

Subjects in the PHS were 22,071 apparently healthy U.S. male physicians, aged 40-84 at entry, without prior history of cardiovascular disease, cancer or other major illnesses. Participants assigned to aspirin who were non-compliant (did not take the 180 study pills per year) had no significant reduction in risk of myocardial infarction.

Furthermore, participants assigned to aspirin who self-selected the use of NSAIDs had no significant reduction in risk of myocardial infarction. All of these observations contribute to the formulation of the researchers' hypothesis that non-adherence or NSAIDs use explains the lack of clinical benefit of aspirin on first myocardial infarction which has been attributed to "aspirin resistance."

Their observations also imply that the interrelationship between laboratory measurements used to indicate inadequate anti-platelet responses to aspirin and "treatment failure" requires evaluation in randomized trials designed to test this hypothesis.

"Aspirin non-response is a clinical reality, but "aspirin resistance" remains a theoretical possibility which requires further research," said Hennekens.

Hennekens' coauthors in these analyses include Wendy Schneider, MSN, RN, affiliate clinical instructor of clinical science and medical education in FAU's College of Biomedical Science; Patricia R. Hebert, Ph.D., research associate professor at FAU; Udaya S. Tantry, Ph.D., laboratory director at Sinai Center for Thrombosis Research in Baltimore, MD; and Paul A. Gurbel, M.D., associate professor of medicine, Johns Hopkins University and director of the Sinai Center for Thrombosis Research in Baltimore, MD.

The American Heart Association recommends aspirin use for prevention of a first heart attack for apparently healthy individuals whose 10 year risk of a first coronary event is greater than 10%. In such moderate and high risk subjects, the benefits of aspirin on occlusion are likely to be greater than the hazards on bleeding.

About Florida Atlantic University:

Florida Atlantic University opened its doors in 1964 as the fifth public university in Florida. Today, the University serves more than 28,000 undergraduate and graduate students on seven campuses and sites.