Personalized antiplatelet therapy: state of the art.

Overwhelming evidence exists that thrombus generation resulting from platelet activation and aggregation is the primary process involved in the occurrence of the myocardial infarction and stent thrombosis. Despite the proven clinical efficacy of dual antiplatelet therapy, wide antiplatelet response variability associated with clopidogrel therapy was demonstrated in pharmacodynamic studies where approximately one in three patients exhibited high on-treatment platelet reactivity (HPR). Generally, physicians do not objectively assess the intensity of the adenosine diphosphate-P2Y12 interaction in their high-risk patients treated with clopidogrel. Instead most clinicians use a non-selective or one-size-fits-all approach. HPR and CYP2C19 LoF carriage are associated with clinical outcomes in high-risk clopidogrel-treated patients who have undergone percutaneous coronary intervention (PCI). Although we do not yet have conclusive evidence from a large-scale randomized trial that personalized antiplatelet therapy improves patient outcomes, a class IIb recommendation has been given in the guidelines to perform genotyping or phenotyping in high-risk PCI patients if a change in antiplatelet therapy will ensue based on the test results. It may be reasonable at this time to assess platelet function and perform genotyping in clopidogrel-treated high-risk patients and treat with more potent P2Y12 receptor therapy selectively.