Pharmacodynamic Evaluation of Switching From Ticagrelor to Clopidogrel in Patients With Coronary Artery Disease

The recommended antiplatelet treatment regimen for patients affected by acute coronary syndromes (ACS) and those undergoing percutaneous coronary intervention (PCI) consists in the combination of aspirin and a P2Y12 receptor inhibitor. Currently, three P2Y12 receptor inhibitors are available for clinical use (clopidogrel, prasugrel, and ticagrelor). Among these, clopidogrel remains the most widely used. However, recent studies have shown that there is a broad variability in platelet-inhibitory response induced by clopidogrel, which in turn is associated with worse outcomes. More potent P2Y12 receptor inhibitors (prasugrel and ticagrelor) have been developed which are associated with less response variability than clopidogrel and better clinical outcomes. Ticagrelor use has increased significantly because of its more expanded Food and Drug Administration (FDA) indications compared with prasugrel. However, despite the evidence for sustained efficacy and safety, many physicians limit treatment duration with ticagrelor to the early phases following an ACS (early weeks or months, rather than one-year) mostly due to cost issues and concerns about increased bleeding. Therefore, it is very common in clinical practice to switch patients while on maintenance dosing (MD) with ticagrelor to treatment with clopidogrel. However, the pharmacodynamic (PD) effects of switching from ticagrelor to clopidogrel remain unknown. In addition, it is unknown whether switching from ticagrelor to clopidogrel should occur with or without a loading dose (LD). Therefore, the aim of this investigation is to evaluate the PD effects of switching from ticagrelor to clopidogrel with and without a LD. The present study has a prospective, randomized, open-label design, in which patients will be treated with 4 different strategies to assess PD profiling after switching. This study will provide important insights on PD effects of switching from ticagrelor to clopidogrel.