Background: A large number of clinical studies have documented that a loss-of-function variant CYP2C19*2 affects clinical profiles of clopidogrel (efficacy and safety). However, data on the impact of a gain-of-function variant CYP2C19*17 on the response to that drug seem to be less consistent.
Objectives: To systematically summarize all available clinical data assessing the role of the CYP2C19*17 variant in patients taking clopidogrel.
Methods: A literature search was conducted and a meta-analysis was performed for 11 eligible studies. The endpoints included the major adverse cardiovascular events (MACE, representing non-fatal myocardial infarction, stroke, revascularization, or death), bleeding events, mortality, stent thrombosis and high platelet reactivity (HPR).
Results: Data from six clinical studies demonstrated that carriers of the CYP2C19*17 variant had a marked protection against recurrent cardiovascular events in patients with coronary artery disease compared with non-carriers, as measured by a 16% decrease in the incidence of MACE (10.0% vs. 11.9%; OR, 0.82; 95% CI, 0.72-0.94; P = 0.005). On the other hand, carriers had an increased risk of developing bleeding as expected (8.0% vs. 6.5%; OR, 1.25; 95% CI, 1.07-1.47; P = 0.006; four studies). Moreover, the presence of the CYP2C19*17 variant might lead to increased response to clopidogrel, as shown by a marked lower prevalence of HPR in carriers than in non-carriers (37.9% vs. 50.8%; OR, 0.60; 95% CI, 0.45-0.79; P = 0.0003; three studies).
Conclusions: Carriers of the CYP2C19*17 variant have greater therapeutic responsiveness to clopidogrel than non-carriers, but they have an increased risk of developing bleeding as well.
© 2011 International Society on Thrombosis and Haemostasis.