Research highlights significant aspirin and Plavix resistance

Previous studies have shown that aspirin resistance is associated with triple the risk of heart attack, stroke and death. Once patients are tested and identified as aspirin resistant, physicians may opt for an alternative approach to therapy, which may include increasing the dosage of aspirin or placing the patient on another antiplatelet medication.

Up to 27% of aspirin users with coronary artery disease (CAD) are resistant to aspirin’s antiplatelet effects, determined by Accumetrics’ VerifyNow Aspirin test, according to research reported by Dr Chen and colleagues at the University of Hong Kong. The results also indicate that women, the elderly and those taking lower doses of aspirin are most likely to be aspirin resistant.

“Knowledge of particular patient groups susceptible to aspirin resistance underscores the need to confirm aspirin response so that alternative or additional antiplatelet therapy can be considered in this population at higher risk,” said Daniel Simon, associate director of interventional cardiology at Brigham and Women’s Hospital and professor of medicine at Harvard University.

“Physicians don’t use coumadin or heparin without monitoring their anti-thrombotic effects. Antiplatelet therapy is no different.”

Additionally, research indicates that resistance to aspirin and clopidogrel (Bristol-Myers Squibb and Sanofi-Aventis’ Plavix) may occur together, according to research presented by Dr Eli Lev and colleagues at Baylor College of Medicine in Houston. In fact, in a study, 50% of those patients resistant to aspirin were also resistant to clopidogrel.

“This study has important implications, as aspirin along with Plavix, are the current standard of care for preventing complications associated with coronary stenting, yet may not be providing adequate antiplatelet protection in all patients,” said Dr Lev.