Aspirin resistance: A fact or a myth?

Blood platelets play a very important role in the pathogenesis of heart attacks and stroke. Therefore, several million individuals all over the world take aspirin, an irreversible inhibitor of the cyclooxygenase enzyme, for the prevention of heart attacks and stroke. Over the past three decades, the author's laboratory has used arachidonic acid-induced platelet aggregation as a standard to monitor aspirin sensitivity. However, there has been no detection of a significant number of nonresponders to the action of aspirin in the normal population. Recent studies from several other laboratories suggest that a significant number of patients suffering various vascular diseases are nonresponders to the action of aspirin and, therefore, are not protected from developing acute vascular events. According to some estimates, anywhere from 4% to 50% of patients taking aspirin are nonresponders. Lack of a specific diagnostic method makes it difficult to detect aspirin resistance in clinical conditions. Therefore, there is an immediate need for the development of a platelet-cyclooxygenase-specific assay to determine the prevalence of aspirin resistance in normal and patient populations. Once determined, an appropriate treatment regimen can be developed for these nonresponding individuals.