Value of CYP2C19 *2 and *17 Genotyping in Clinical Practice. Promising but Not Ready Yet Valor de la determinación del genotipo de CYP2C19 *2 y *17 en la práctica clı́nica. Prometedor, aunque todavı́a no está listo

Numerous studies have shown the preventive effect of the use of dual antiplatelet therapy using acetylsalicylic acid and clopidogrel in reducing the risk of cardiovascular events in patients after acute coronary syndrome (ACS) and those undergoing percutaneous coronary intervention (PCI). Consequently every clinical guideline has incorporated the use of dual antiplatelet therapy for ACS and PCI patients: clopidogrel for 1 year and acetylsalicylic acid for life. Clopidogrel is a prodrug which needs several biotransformation steps using cytochrome (CYP) P450 liver enzymes before it acquires its antiplatelet effect. After the activation steps clopidogrel irreversibly blocks the P2Y12 adenosine diphosphate receptor, which is a key mediator of platelet activation. However, despite the success of clopidogrel, making it the second most prescribed drug in the world, a substantial number of patients still suffer from recurrent atherothrombotic events after ACS with or without PCI. Stent thrombosis is an especially feared complication associated with substantial mortality (15% to 45% of cases).