Background: P2Y12 receptor inhibitors are crucial for the management of patients undergoing coronary stenting. Although large-scale trials have shown that ticagrelor is superior to clopidogrel in terms of platelet inhibition and reduction of major adverse cardiovascular events (MACE), clopidogrel remains the most commonly used P2Y12 receptor inhibitor due to its lower price and bleeding risk. Despite the combined use of aspirin and clopidogrel, a substantial portion of patients after coronary stenting are at increased risk for adverse cardiovascular events including death, myocardial infarction, and stent thrombosis. This phenomenon may be due to the so-called clopidogrel resistance. Cytochrome P450 2C19 (CYP2C19) polymorphism plays a crucial role in the clopidogrel resistance. CYP2C19 is responsible, in part, for converting the clopidogrel prodrug into an active metabolite that irreversibly binds to the P2Y12 receptor thus inhibiting ADP-induced platelet aggregation. CYP2C19*2 and *3, which encounter loss function, have been demonstrated to be the most common genetic variants resulting in clopidogrel resistance.~Methods: Patients who undergo coronary stenting will be randomized to a prospective CYP2C19 genotype-guided antiplatelet therapy arm versus a conventional therapy arm. Venous blood collection will be completed immediately after randomization in all patients eligible for the study. The genotype results involving CYP2C19*2 and *3 allele variants will be obtained within 48 hours only in the genotyping arm. CYP2C19 *2 or *3 reduced function allele patients will receive ticagrelor 90 mg bid, whereas non-*2 or -*3 CYP2C19 patients will receive clopidogrel 75 mg once daily. The conventional therapy arm will receive either clopidogrel or ticagrelor, according to the clinical and procedural characteristics of patients. The dual antiplatelet therapy will last for at least one year in the both arms. The primary endpoints will be evaluated at one-year follow-up.
The aim of this study is to assess the efficacy and safety of the CYP2C19 genotype guided antiplatelet treatment strategy, using clopidogrel in non-carriers of a CYP2C19*2 or *3 allele and ticagrelor in carriers of a CYP2C19*2 or *3 allele in patients treated with new generation drug eluting stents.