Role of CYP2C19 genotype testing in clinical use of clopidogrel: is it really useful?

P2Y12 inhibitors, including clopidogrel have become an integral part of treatment for patients receiving coronary stent placement as a result of stable coronary artery disease or acute coronary syndromes (ACS) and also for medically managed ACS patients. Areas covered: Clopidogrel efficacy can be significantly modified by polymorphism of CYP2C19 genotype (more than 25 allelic variants) involved in its metabolism that can adversely affect its anti-platelet activity. As a result, a substantial number of patients (20-30%) with ACS show an inadequate response to clopidogrel despite a standardized dosing regimen. Experts commentary: Currently, there is conflicting evidence in regards to the use of CYP2C19 genotyping to identify poor responders to clopidogrel in clinical practice. ACC/AHA guidelines do not recommend routine use of CYP2C19 in clinical practice, whereas Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines recommend its use to identify poor/intermediate metabolizers of Clopidogrel and suggest alternative P2Y12 inhibitors among ACS patients undergoing percutaneous coronary intervention. This review article will look at the literature evidence for the use of CYP2C19 genotyping in clinical practice.