Overcoming 'resistance' to antiplatelet therapy: targeting the issue of nonadherence.

A wide range of interindividual variability in the measured and clinical effects of antiplatelet drugs exists. As patients with less platelet inhibition consistently have increased rates of adverse cardiovascular outcomes, a great deal of effort is being focused on understanding and treating this apparent 'resistance.' Pharmacogenomic and pharmacodynamic methods to better delineate responders from nonresponders are being developed, and innovative strategies and novel, potent drugs capable of overcoming nonresponsiveness are in active clinical trials. Less attention has been paid to the confounding role that patient nonadherence has on individual response to antiplatelet therapy, but accruing evidence indicates that nonadherence has a dominant impact in real-world, outpatient settings, as compared with true, biochemical antiplatelet nonresponsiveness. Understanding the mechanisms of nonadherence and rigorously testing methods to overcome it are urgently needed to avoid the potential harm in delivering increasingly intense and expensive therapies to those who may not need it, while at the same time offering a way to improve overall health-care efficiency.