Aspirin Resistance and Its Implications in Clinical Practice

John Eikelboom, MBBS, MSc; Mark Feldman, MD: Shamir R. Mehta, MD, MSc; Alan D. Michelson, MD; John A. Oates, MD; Eric Topol, MDContributors: Miriam Reisman, MFA; Stephen D. Lande, PhD

Disclosures
In This Article

Abstract and Introduction

Recent studies have suggested that some patients may not obtain the full benefits of aspirin's antiplatelet effects. An international roundtable of experts was held November 6, 2004, in New Orleans, Louisiana, to address the concept of aspirin resistance and its clinical implications. Panelists discussed various definitions and possible mechanisms of aspirin resistance, along with several tests currently available to measure platelet function. They recommended that until the clinical importance of these tests is known, physicians should continue to prescribe low-dose aspirin therapy for individuals at high risk for cardiovascular events and patients currently taking aspirin should continue to comply with their prescribed therapy.

Aspirin therapy has long been known to be an effective method of preventing heart attacks and strokes. This benefit stems from the ability of aspirin to irreversibly inhibit platelet aggregation, which in turn reduces the risk of vascular occlusion. However, several recent studies have suggested that some patients may not get the full benefits of aspirin's antiplatelet effects. These findings have raised many questions for clinicians: Are some patients resistant to aspirin's antiplatelet effects? If so, how should aspirin resistance be defined? What causes it? Should patients be tested for it? Should aspirin therapy be altered on the basis of these tests?

On November 6, 2004, an international panel convened for a roundtable meeting in New Orleans prior to the American Heart Association Scientific Sessions to address these critical issues. Panel members representing a range of disciplines including cardiology, clinical pharmacology, hematology, and gastroenterology examined the current literature along with a number of case studies and provided insight into the concept of aspirin resistance and its implications in clinical practice.

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