Loss-of-function Allele Carriers Research Articles

Abstract 11802: Clinical Implementation Of CYP2C19-genotype Guided Antiplatelet Therapy Reduces Cardiovascular Events After PCI

Introduction: Clopidogrel is bioactivated by CYP2C19, and the CYP2C19 loss-of-function (LOF) genotype leads to reduced clopidogrel effectiveness after percutaneous coronary intervention (PCI). We examined whether clinical implementation of CYP2C19 genotype-guided antiplatelet therapy (APT) reduces the risk for cardiovascular events after PCI. Methods: CYP2C19 genotyping post-PCI was implemented at UF Health Shands Hospital in July 2012, with alternative APT recommended for LOF allele carriers. Major adverse cardiovascular events (MACE, comprised of cardiovascular death, MI, stroke and stent thrombosis) over the 6 months after PCI were determined via medical record review. MACE was compared between LOF allele carriers switched to alternative APT (LOF-alternative) and both LOF allele carriers who remained on clopidogrel (LOF-clopidogrel) and non-LOF carriers (non-LOF) using Kaplan-Meier method with additional multivariable Cox regression analysis and propensity score adjustment in LOF groups. Results: Of 412 patients (80% with ACS) who underwent PCI and genotyping, 126 (31%) had a LOF allele and 68 (54%) of these received alternative APT (prasugrel n=57, ticagrelor n=8, triple dose clopidogrel n=3). On Kaplan-Meier analysis (Figure), there was a lower incidence of MACE in LOF-alternative vs. LOF-clopidogrel groups and no significant difference between the LOF-alternative and non-LOF groups. On multivariable Cox regression analysis with propensity score adjustment, there was reduced risk of MACE in LOF-alternative vs. LOF-clopidogrel patients (HR 0.09, 95% CI 0.01-0.84, p=0.035). In the LOF-clopidogrel group, the majority of events (83%) occurred within 30 days; all were in patients who presented with an ACS. Conclusion: Changing from clopidogrel to alternative APT after PCI in patients with the CYP2C19 LOF genotype reduces the risk for MACE. These data support CYP2C19 genotyping in patients undergoing PCI, especially in those with ACS.

Patients with both CYP2C19 loss-of-function allele and peripheral endothelial dysfunction are significantly correlated with adverse cardiovascular events following coronary stent implantation

BackgroundThere is some controversy regarding the effect of CYP2C19 polymorphism on clinical outcome in patients receiving dual antiplatelet therapy (DAPT). Peripheral endothelial dysfunction has recently been reported to predict adverse cardiovascular events. We hypothesized that CYP2C19 loss-of-function (LOF) allele carriers with peripheral endothelial dysfunction had worse prognosis. The aim of this study was to evaluate an additive effect of peripheral endothelial dysfunction on clinical outcome following percutaneous coronary intervention (PCI) in patients with a CYP2C19 variant. MethodsWe enrolled 434 patients on DAPT following PCI. CYP2C19 genotype was examined, and we divided patients into two groups: carriers, who had at least one CYP2C19 LOF allele, and non-carriers. Peripheral endothelial dysfunction was examined using reactive hyperemia-peripheral arterial tonometry index (RHI), and we divided patients into low and high RHI. Thus, subjects were divided into four groups, and clinical events were followed up. ResultsA total of 55 patients had a cardiovascular event. Kaplan–Meier analysis demonstrated a significantly higher probability of cardiovascular events in carriers with low RHI (log-rank test: p=0.007). Multivariate Cox proportional hazards analysis identified both CYP2C19 LOF allele possession (hazard ratio (HR): 1.94; 95% confidence interval (CI): 1.1–3.69; p=0.045) and low RHI (HR: 2.15; 95% CI: 1.22–3.78; p=0.008) as independent and significant predictors of future cardiovascular events. ConclusionsCYP2C19 LOF allele carriers with peripheral endothelial dysfunction were significantly correlated with cardiovascular events. The additional evaluation of peripheral endothelial function along with CYP2C19 polymorphism might improve risk stratification after coronary stent implantation.

Defining predictive values using three different platelet function tests for CYP2C19 phenotype status on maintenance dual antiplatelet therapy after PCI

Published data suggests that the presence of CYP2C19*2 or *3 loss of function (LOF) alleles is indicative of increased platelet aggregation and a higher risk of adverse cardiovascular events after clopidogrel administration. We sought to determine cut-off values using three different assays for prediction of the CYP2C19 phenotype in Korean percutaneous coronary intervention (PCI) patients. We enrolled 244 patients with drug-eluting stent implantation who were receiving clopidogrel and aspirin maintenance therapy for one month or more. Platelet reactivity was assessed with light transmittance aggregometry (LTA), multiple electrode aggregometry (MEA) and the VerifyNow P2Y12 assay (VN). The CYP2C19 genotype was analyzed by polymerase chain reaction (PCR) and snapshot method. The frequency of CYP2C19 LOF allele carriers was 58.6%. The cut-off values from LTA, MEA and VerifyNow for the identification of LOF allele carriers were as follows: 10 µM ADP-induced LTA ≥ 48 %, VN > 242 PRU and MEA ≥ 37 U. Between the three tests, correlation was higher between LTA vs. VN assays (r = 0.69) and LTA vs. MEA (r = 0.56), with moderate agreement (κ = 0.46 and κ = 0.46), but between VN assay and MEA, both devices using whole blood showed a lower correlation (r = 0.42) and agreement (κ = 0.3). Our results provide guidance regarding cut-off levels for LTA, VerifyNow and MEA assays to detect the CYP2C19 LOF allele in patients during dual antiplatelet maintenance therapy.