Clinical Utility of CYP2C19 Genotyping to Guide Antiplatelet Therapy in Patients With an Acute Coronary Syndrome or Undergoing Percutaneous Coronary Intervention.

Current guidelines recommend dual antiplatelet therapy-a P2Y inhibitor (clopidogrel, prasugrel, or ticagrelor) and aspirin-for patients undergoing percutaneous coronary intervention. Although clopidogrel is the most commonly prescribed P2Y inhibitor, it is associated with an increased risk of major adverse cardiovascular events in patients carrying loss-of-function CYP2C19 alleles. In contrast, CYP2C19 genotype does not impact clinical response to prasugrel or ticagrelor. Nevertheless, routine implementation of CYP2C19 genotyping to guide antiplatelet therapy selection has remained controversial because of the lack of large randomized controlled trials evaluating this strategy. Emerging results from registry studies and small clinical trials of CYP2C19 genotype-guided antiplatelet therapy following percutaneous coronary intervention offer new insight and contribute to a growing evidence base that supports the clinical utility of a genotyping strategy to personalize antiplatelet therapy selection.