Platelet function testing in contemporary clinical and interventional practice

Dual antiplatelet therapy with a combination of aspirin and an inhibitor of the ADP P2Y12 receptor is the recommended treatment for patients with acute coronary syndrome or who are undergoing percutaneous coronary intervention (PCI). However, patients may continue to have ischemic recurrences, including stent thrombosis, which have been linked with the well-known variability in individual response to antiplatelet therapy, and clopidogrel in particular. There are currently several assays available to measure platelet reactivity, and platelet function testing has been shown to be a valuable tool to assess the pharmacodynamic efficacy of antiplatelet drugs. Moreover, platelet reactivity has important prognostic implications, as several studies have shown an association with thrombotic and bleeding events in patients with high and low platelet reactivity, respectively. Consequently, over the past years there has been a plethora of studies investigating the optimal range of platelet reactivity associated with the highest protection against ischemic complications and the lowest risk of bleeding. Given the correlation between on-treatment platelet reactivity and outcomes, the use of platelet function testing has also been advocated to create personalized antiplatelet therapy. Several studies have been conducted in this field, but major clinical trials have failed to demonstrate a benefit of such a strategy in improving clinical outcomes. Indeed, inherent limitations of these trials may have contributed to their failure. The present manuscript provides an overview on the role of platelet function testing in contemporary clinical and interventional practice.