Independent Predictors Of High On-treatment Platelet Reactivity Research Articles

CD80 DNA methylation and single-nucleotide polymorphism associated with clopidogrel response: a whole-genome DNA methylation analysis in acute coronary syndrome

BackgroundDual antiplatelet therapy with clopidogrel and aspirin is the primary treatment for patients who undergo percutaneous coronary intervention. However, the interindividual difference in clopidogrel response is remarkable, and high on-treatment platelet reactivity (HTPR) can increase the risk of thrombotic events after percutaneous coronary intervention. ObjectiveWe studied novel accessible factors that possibly affect clopidogrel response in DNA methylation. MethodsMethylation 850K bead chips were used to detect DNA methylation levels. The platelet reactivity index (PRI) was determined in 330 subjects with acute coronary syndrome (ACS) after administration of clopidogrel 300 mg loading dose or at least 5 days of 75 mg daily maintenance dose. ResultsOverall, 32 discovery samples showed extreme clopidogrel response: 16 with HTPR (PRI > 75%) and 16 with non-HTPR (PRI < 26%). Overall, 61 differential methylation loci (DMLs) were observed between the 2 groups. Most were in the open sea and intergenic regions in the genome. In the validation stage, HTPR showed a lower level of CD80_cg06300880 methylation. Carriers of rs34394661 AA genotype, a CpG-single-nucleotide polymorphism at the CD80_cg06300880 locus, showed an increased odds for HTPR (overall odds ratio of patients with ACS = 7.31, 95% CI: 1.69-31.59, P = .008; non-ST elevation myocardial infarction-ACS: odds ratio = 12.69, 95% CI: 1.68-96.08, P = .01) and decreased CD80_cg06300880 methylation (P < .0001). Multivariate regression analysis showed that both CYP2C19 poor metabolizers and CD80_rs34394661 AA (P = .009) genotype were associated with higher odds for HTPR in the overall samples. In contrast, CD80_cg06300880 methylation (P = .002) caused lower odds for HTPR in patients with non-ST elevation myocardial infarction-ACS. ConclusionCD80_cg06300880 and CpG-single-nucleotide polymorphism rs34394661 could be independent predictors of HTPR with clopidogrel therapy.

High triglyceride is an independent predictor of high on-treatment platelet reactivity in ischemic stroke patients

BackgroundPrevious studies have shown high triglyceride (TG) is associated with platelet hyperactivation in metabolic syndrome patients. However, limited information is available regarding this relationship on dual anti-platelet therapy (DAPT) in ischemic stroke (IS). In this study, we attempted to evaluate the association between TG and high on-treatment platelet reactivity (HTPR) in IS patients. MethodsIschemic stroke patients who received maintenance doses of clopidogrel and aspirin were categorized and analyzed retrospectively in this research. The platelet reactivity was assessed by Thromboelastography (TEG). If ADP-induced platelet inhibition rate (ADPi)<30%, it was defined as HTPR, else, it would be defined as normal on-treatment platelet reactivity (NTPR). Patients were divided into high-TG-level and lower-TG-level based on a TG level of 1.7mmol/L, the cutoff point of hypertriglyceridemia. A logistic regression model was applied to calculate the odds ratio (OR) and 95% confidence interval (CI). ResultsA total of 123 patients were included in this study and 24 (19.51%) patients were identified as HTPR. HTPR was observed in 36.2% of the patients in high-TG-level (TG≥1.7mmol/L) group while only 9.2% of the patients in the low-TG-level group (TG<1.7mmol/L) were HTPR (P<0.001 ). According to multivariate analysis, TG≥1.7mmol/L was independently associated with HTPR (OR=14.715, 2.445-88.549,P=0.003). ConclusionsHigh TG is an independent predictor of HTPR in IS patients. For IS patients with high TG level undergoing DAPT, platelet reactivity should be monitored to identify HTPR, which may proactively help to optimize the anti-platelet therapy.

Dual Antiplatelet Therapy with 3rd Generation P2Y12 Inhibitors in STEMI Patients: Impact of Body Mass Index on Loading Dose-Response.

This study aims to assess the association between body mass index (BMI) and platelet reactivity in STEMI patients treated with oral 3rd generation P2Y12 inhibitors. Overall, 429 STEMI patients were enrolled in this study. Patients were divided into two groups according to BMI (BMI < 25 vs ≥ 25kg/m2). A propensity score matching (1:1) was performed to balance potential confounders in patient baseline characteristics. Platelet reactivity was assessed by VerifyNow at baseline and after 3rd generation P2Y12 inhibitor (ticagrelor or prasugrel) loading dose (LD). Blood samples were obtained at baseline (T0), 1h (T1), 2h (T2), 4-6h (T3), and 8-12h (T4) after the LD. High on-treatment platelet reactivity (HTPR) was defined as a platelet reactivity unit value ≥ 208 units. After propensity score matching, patients with BMI ≥ 25 had similar values of baseline platelet reactivity, while they had higher level of platelet reactivity at 1 and 2h after the LD and higher rate of HRPT. Furthermore, multivariate analysis demonstrated that BMI ≥ 25 was an independent predictor of HTPR at 2h (OR 2.01, p = .009). Conversely, starting from 4h after the LD, platelet reactivity values and HRPT rates were comparable among the two study groups. A BMI ≥ 25kg/m2 is associated with delayed pharmacodynamic response to oral 3rd generation P2Y12 inhibitor LD, and it is a strong predictor of HTPR in STEMI patients treated by dual antiplatelet therapy with ticagrelor or prasugrel.

P6406Platelet reactivity in Hepatitis C virus infected patients on dual antiplatelet therapy for acute coronary syndrome

Abstract Background Coronary artery disease (CAD) has been recognized as a serious and potentially life-threatening complication of Hepatitis C Virus (HCV) infection. High on treatment platelet reactivity has been associated with high risk of ischemic events in patients with CAD, but data regarding the association with HCV infection are still lacking. Purpose We sought to assess platelet reactivity on dual anti-platelet therapy and long-term outcome of acute coronary syndrome (ACS) patients infected with HCV. Methods ACS patients infected with HCV were matched to ACS patients without HCV for age, sex, diabetes, hypertension and renal function. Primary and secondary study endpoints were the proportion of patients with high on treatment platelet reactivity (HTPR) and long-term outcomes, respectively. Results HCV-infected ACS patients had higher levels of platelet reactivity (ADP10-LTA: 56% ± 18% vs. 44% ± 22%; p=0.002; Arachidonic Acid-LTA: 25% ± 21% vs. 16% ± 15%; p=0.011) and higher rate of HTPR on clopidogrel and aspirin compared with non-HCV patients. Multivariable analysis demonstrated HCV-infection to be an independent predictor of HTPR. At follow-up, estimated major adverse clinical events (MACE: cardiac death, non fatal myocardial infarction and any revascularization) were 57% vs. 37%, p=0.006 in HCV-infected ACS and non-HCV, respectively. Also, TIMI major bleeding rates were higher in HCV-infected subjects (11% vs. 3%; p=0.043) as compared with non-infected patients. Platelet function according to HCV status Conclusions ACS patients with HCV infection have increased on treatment platelet reactivity, higher rate of HTPR, MACE and bleedings as compared with non-HCV patients.

Prevalence and predictors of high-on treatment platelet reactivity during prasugrel treatment in patients with acute coronary syndrome undergoing stent implantation

BackgroundADP-antagonists such as prasugrel have reduced but yet not overcome the phenomenon of high-on treatment platelet reactivity (HRPR), that has been shown to increase the rate of major cardiovascular events after an acute coronary syndrome (ACS) or percutaneous coronary intervention (PCI). However, the exact prevalence and the principal determinants of suboptimal platelet inhibition in patients treated with dual antiplatelet therapy (DAPT) with prasugrel have not been completely clarified and were therefore the aim of the present study. MethodsWe included patients (<75 years and >60kg) treated with DAPT (aspirin+prasugrel) after PCI, mainly for an ACS. Platelet function test evaluation was performed at 1–3 months from discharge. HRPR was assessed by multiplate impedance aggregometry and defined for results above upper limit of normal after ADP stimulation. ResultsWe included 190 post-ACS patients. HRPR with prasugrel was observed in 19 patients (10%). The prevalence of HRPR was stable in different high-risk subgroups of patients (female gender, hypercholesterolemic, and chronic kidney disease) whereas it was increased in diabetic patients (p=0.045), with a significant interaction between diabetic status and HRPR (p=0.04). However, at multivariate analysis, an impaired metabolic status, with higher levels of glycosylated hemoglobin and low-density lipoprotein (LDL) cholesterol, but not diabetic status, emerged as independent predictors of HRPR with prasugrel [OR (95% CI)=2.1 (1.32–3.33), p=0.002 and OR (95% CI)=1.03 (1.01–1.05), p=0.003, respectively], with a stronger linear relationship between ADP-mediated platelet aggregation and glycosylated hemoglobin levels (r=0.24, p=0.002), than for LDL-cholesterol (r=0.13, p=0.09). ConclusionsIn post-ACS patients treated with PCI and receiving DAPT with prasugrel, HRPR is observed in about 10% of patients. Impaired metabolic status, and especially elevated glycosylated hemoglobin, emerged as independent predictors of the suboptimal effectiveness of prasugrel.

2042 CYP2C19*2 and PON1 Q192R polymorphisms are associated with platelet reactivity to clopidogrel in Puerto Rican Hispanics with cardiovascular disease

OBJECTIVES/SPECIFIC AIMS: High on-treatment platelet reactivity (HTPR) with clopidogrel imparts an increased risk for ischemic events in adults with coronary artery disease. Although more potent antiplatelet agents are available, clopidogrel remains the most commonly used P2Y12 inhibitor in Puerto Rico. Platelet reactivity varies with ethnicity and is influenced by both clinical and genetic variables; however, no clopidogrel pharmacogenetic studies with Puerto Rican patients have been reported. Therefore, we sought to identify clinical and genetic determinants of on-treatment platelet reactivity in a cohort of Puerto Rican patients with cardiovascular disease. METHODS/STUDY POPULATION: We performed a retrospective study of 111 Puerto Rican patients on 75 mg/day maintenance dose of clopidogrel. Patients were allocated into 2 groups: Group I, without HTPR; and Group II, with HTPR. Clinical data was obtained from the medical record. Platelet function was measured ex vivo using the VerifyNow® P2Y12 assay and HTPR was defined as P2Y12 reaction units (PRU)≥230. Genotyping of CYP2C19, ABCB1, PON1, PY2R12, B4GALT2, CES1, and PEAR1 was performed using Taqman® Genotyping Assays. RESULTS/ANTICIPATED RESULTS: The mean PRU across the cohort was 203±61 PRU (range, 8–324), and 42 (38%) patients had HTPR. One in four individuals carried at least 1 copy of the CYP2C19*2 variant allele. Hematocrit and PON1 p.Q192R variant were inversely correlated with platelet reactivity (p&lt;0.05). Multiple logistic regression showed that 27% of the total variation in PRU was explained by a history of diabetes mellitus, hematocrit, CYP2C19*2, and PON1 p.Q192R. Body mass index (OR=1.15; CI: 1.03–1.27), diabetes mellitus (OR=3.46; CI: 1.05–11.43), hematocrit (OR=0.75; CI: 0.65–0.87), and CYP2C19*2 (OR=4.44; CI: 1.21–16.20) were the only independent predictors of HTPR. DISCUSSION/SIGNIFICANCE OF IMPACT: In a representative sample of Puerto Rican patients with cardiovascular disease, diabetes mellitus, hematocrit, CYP2C19*2, and PON1 p.Q192R were associated with on-treatment platelet reactivity. These factors may identify a subset of patients at higher risk for adverse events on clopidogrel in the Hispanic population.

Association of serum levels of lipoprotein A-I and lipoprotein A-I/A-II with high on-treatment platelet reactivity in patients with ST-segment elevation myocardial infarction.

ObjectiveHigh-density lipoproteins (HDLs) are a very heterogeneous group of particles. Little is known about the impact of their subfractions including lipoprotein A-I (LpA-I) and lipoprotein A-I/A-II (LpA-I/A-II) on platelet function and high on-treatment platelet reactivity (HPR), particularly in the acute phase of ST-segment elevation myocardial infarction (STEMI). The aim of the study was to evaluate the relationship between serum levels of LpA-I and LpA-I/A-II and HPR in STEMI patients.MethodsFifty-two consecutive STEMI patients (26.9% women, mean age 60.6±9.1 years) were enrolled into this study. Clinical and demographic data were collected and HDL subfractions were measured by rocket immunoelectrophoresis. Platelet reactivity was assessed using light transmission aggregometry and quantitative flow cytometry.ResultsWe found a positive correlation between platelet aggregation after both ADP-5 and ADP-20 stimulation and serum level of LpA-I. Compared with subjects with satisfactory platelet response to clopidogrel, patients with HPR had 32.44% higher serum level of LpA-I (p=0.021). On the other hand, patients with HPR assessed by ADP-5 stimulation had 22.13% lower serum level of LpA-I/A-II (p=0.040). Regression analysis showed that LpA-I [odds ratio (OR) 1.03; 95% confidence interval (CI) 1-1.07; p=0.049] and current smoking (OR 0.18; 95% CI 0.04-0.81; p=0.025) were independent predictors of HPR. With receiver operating characteristic (ROC) curve analysis, we designated the cut-off point at serum level of 57.52 mg/dL for LpA-I for predicting HPR (AUC=0.71, p=0.010).ConclusionThis study showed that higher serum level of LpA-I measured in the acute phase of STEMI is an independent risk factor for HPR. Our study is the first to demonstrate an important and distinct activity of LpA-I and LpA-I/A-II that can prove pleiotropic and different functions of HDL subfractions in acute STEMI.

High On-Treatment Platelet Reactivity Determinants on Dual Antiplatelet Therapy in Patients With Ischemic Heart Disease Before Elective Percutaneous Coronary Intervention.

to determine impact of different laboratory and genetic factors on high on-treatment platelet reactivity (HOPR) during dual antiplatelet therapy (DAPT). We included in this study 94 patients with stable ischemic heart disease (mean age 59±9.67 years). All patients underwent elective PCI with implantation of drug eluting stents at the background of dual antiplatelet therapy (DAPT) with aspirin and clopidogrel. Platelet reactivity was assessed using light transmission aggregometry with 5 μmol/L ADP (LTA 5ADP) and VerifyNow assay before PCI. All patients underwent genotyping to detect CYP2C19 polymorphism. In 74 patients at baseline examination we determined levels of high-sensitivity C-reactive protein (hsCPR), soluble platelet-selectin (sP-selectin), soluble CD40-ligand (sCD40L), interleukin-6 (IL-6), plasminogen activator inhibitor (PAI-1) and activity of von Willebrand factor. Incidence of HOPR according to LTA-5ADP was 16% and VerifyNow - 24.5%. Univariate regression analysis showed that the following factors were significantly associated with HPR determined by LTA-5ADP: body mass index (BMI) (p=0.02), levels of total cholesterol (CH) (p=0.0l), low density lipoprotein CH (p=0.004), and sP-selectin (p=0.009), activity of von Willebrand factor (p=0.04). Carriage of CYP2C19*2 allele was also associated with HOPR (p=0.006). According to multivariate regression analysis body mass index and level of sP-selectin were independent predictors of HOPR during DAPT. HOPR determined by LTA was significantly associated with high BMI, levels of total and LDL CH, carriage of CYP2C19*2 allele, levels of hsCRP and sP-selectin. Independent factors significantly related to HORP were BMI and sP-selectin level.

Clinical determinants of clopidogrel responsiveness in a heterogeneous cohort of Puerto Rican Hispanics.

Clopidogrel is by far the most prescribed platelet adenosine diphosphate (ADP) antagonist in Puerto Rico despite the advent of newer agents (prasugrel and ticagrelor). Given the paucity of data on clopidogrel responsiveness in Hispanics, we sought to determine the association between clinical characteristics and platelet reactivity in Puerto Rican patients on clopidogrel therapy. A total of 100 Puerto Rican patients on clopidogrel therapy were enrolled and allocated into two groups: Group I, without high on-treatment platelet reactivity (HTPR); and Group II, with HTPR. Platelet function was measured ex vivo using the VerifyNow® P2Y12 assay. The cohort was comprised of Hispanic patients with coronary artery disease (57%), peripheral artery disease (32%), carotid artery stenosis (7%), cerebral artery aneurysm (2%), and stroke (2%). Mean platelet reactivity was 200 ± 61 P2Y12 reaction units (PRUs) (range: 8-324), and 35% of patients had HTPR (PRUs ⩾ 230). Multivariable logistic regression analysis determined that diabetes mellitus (DM) [odds ratio (OR) = 3.27; 95% confidence interval (CI): 1.20-8.96], use of proton-pump inhibitors (PPIs) (OR = 3.60; 95% CI: 1.09-11.82), and calcium channel blockers (CCBs) (OR = 3.10; 95% CI: 1.09-8.83) were independent predictors of HTPR ( p < 0.05) after adjusting for other clinical variables. In a sample of 100 Puerto Rican Hispanic patients on clopidogrel, 35% had HTPR. Furthermore, DM, PPIs and CCBs predicted HTPR. Clinical outcome data are needed to identify appropriate PRU thresholds for risk prediction in the Puerto Rican population.

Association of PEAR1 genetic variants with platelet reactivity in response to dual antiplatelet therapy with aspirin and clopidogrel in the Chinese patient population after percutaneous coronary intervention

IntroductionPlatelet Endothelial Aggregation Receptor-1 (PEAR1) is a recently reported platelet transmembrane protein which plays an important role in platelet aggregation. The aim of this study was to investigate whether PEAR1 genetic variations were associated with platelet reactivity as assessed by adenosine diphosphate(ADP)-induced platelet aggregation in Chinese patients treated with aspirin and clopidogrel. MethodsPatients with coronary heart disease (CHD) who underwent percutaneous coronary intervention (PCI) were enrolled in the study. All patients were on dual antiplatelet therapy with aspirin and clopidogrel. ADP-induced platelet aggregation was measured by thromboelastography and defined as percent inhibition of platelet aggregation (IPA). Patients (n=204) with IPA <30% were identified as high on-treatment platelet reactivity (HPR). Patients (n=201) with IPA >70% were identified as low on-treatment platelet reactivity (LPR). Sixteen single nucleotide polymorphisms (SNPs) of PEAR1 were determined by a method of improved multiple ligase detection reaction. ResultsAmong the 16 SNPs examined by univariate analysis, 5 SNPs were significantly associated with ADP-induced platelet aggregation. Minor allele C at rs11264580 (p=0.033), minor allele G at rs2644592 (p=0.048), minor allele T at rs3737224 (p=0.033) and minor allele T at rs41273215 (p=0.025) were strongly associated with HPR, whereas homozygous TT genotype at rs57731889 (p=0.009) was associated with LPR. Multivariate logistic regression analysis further revealed that the minor allele T at rs41273215 (p=0.038) was an independent predictor of HPR and the homozygous TT genotype at rs57731889 (p=0.003) was an independent predictor of LPR. ConclusionsPEAR1 genetic variations were strongly associated with ADP-induced platelet aggregation in Chinese patients with CHD treated with aspirin and clopidogrel. These genetic variations may contribute to the variability in platelet function. The utility of PEAR1 genetic variants in the assessment and prediction of cardiovascular risk warrants further investigation.

Prevalence and predictors of high-on treatment platelet reactivity with ticagrelor in ACS patients undergoing stent implantation

BackgroundResidual high-on treatment platelet reactivity (HRPR) predicts outcomes and major cardiovascular events. Ticagrelor has provided pharmacological and clinical evidence of more predictable and more potent antiplatelet effect as compared to clopidogrel. However, so far, few data have investigated the prevalence and predictors of HRPR in unselected patients treated with ticagrelor, that is therefore the aim of the current study. Methods and resultsOur population is represented by 195 patients undergoing coronary stenting for ACS and receiving ASA and ticagrelor. Platelet function was assessed by multiplate impedance aggregometry (MEA) between 1 and 3months after stenting. Main clinical features and biochemistry parameters were collected. HRPR for ticagrelor was defined for aggregation>417 AUC after MEA-ADP stimulation. A total of 26 patients, (13.3%), displayed HRPR with ticagrelor. Older age (≥70years, p=0.002), hypertension (p=0.02) previous myocardial infarction (p=0.04), therapy with nitrates and beta-blockers (p=0.02), diuretics (p=0.03) and fasting glycaemia (p=0.05) were associated to HRPR with ticagrelor. By multivariate analysis, age≥70years (OR [95%CI]=4.6[1.55–13.8], p=0.006), concomitant therapy with beta-blockers (OR [95%CI]=3.2[1.06–9.6], p=0.04) and platelets count (OR[95%CI]=1.0007 [1–1.016], p=0.05) were identified as independent predictors of HRPR with ticagrelor. ConclusionThe present study firstly demonstrates that the occurrence of HRPR in patients treated with ticagrelor is not so futile, as it was observed in 13% of patients treated with ticagrelor. Older age, beta-blockers administration and platelets count are independent predictors of HRPR with ticagrelor.

Evaluation of clinical risk factors to predict high on-treatment platelet reactivity and outcome in patients with stable coronary artery disease (PREDICT-STABLE).

ObjectivesThis study was designed to identify the multivariate effect of clinical risk factors on high on-treatment platelet reactivity (HPR) and 12 months major adverse events (MACE) under treatment with aspirin and clopidogrel in patients undergoing non-urgent percutaneous coronary intervention (PCI).Methods739 consecutive patients with stable coronary artery disease (CAD) undergoing PCI were recruited. On-treatment platelet aggregation was tested by light transmittance aggregometry. Clinical risk factors and MACE during one-year follow-up were recorded. An independent population of 591 patients served as validation cohort.ResultsDegree of on-treatment platelet aggregation was influenced by different clinical risk factors. In multivariate regression analysis older age, diabetes mellitus, elevated BMI, renal function and left ventricular ejection fraction were independent predictors of HPR. After weighing these variables according to their estimates in multivariate regression model, we developed a score to predict HPR in stable CAD patients undergoing elective PCI (PREDICT-STABLE Score, ranging 0-9). Patients with a high score were significantly more likely to develop MACE within one year of follow-up, 3.4% (score 0-3), 6.3% (score 4-6) and 10.3% (score 7-9); odds ratio 3.23, P=0.02 for score 7-9 vs. 0-3. This association was confirmed in the validation cohort.ConclusionsVariability of on-treatment platelet function and associated outcome is mainly influenced by clinical risk variables. Identification of high risk patients (e.g. with high PREDICT-STABLE score) might help to identify risk groups that benefit from more intensified antiplatelet regimen. Additional clinical risk factor assessment rather than isolated platelet function-guided approaches should be investigated in future to evaluate personalized antiplatelet therapy in stable CAD-patients.

Dipstick proteinuria is an independent predictor of high on treatment platelet reactivity in patients on clopidogrel, but not aspirin, admitted for major adverse cardiovascular events

The effectiveness of aspirin and clopidogrel in patients with chronic kidney disease (CKD) suffering from acute cardiovascular events is unclear. High on treatment platelet reactivity (HTPR) has been associated with worse outcomes. Here, we assessed the association of dipstick proteinuria (DP) and renal function on HTPR and clinical outcomes. Retrospective cohort analysis of 261 consecutive, non-dialysis patients admitted for Major Adverse Cardiovascular Events (MACE) that had VerifyNow P2Y12 and VerifyNow Aspirin assays performed. HTPR was defined as P2Y12 reactivity unit (PRU) > 208 for clopidogrel and aspirin reaction units (ARU) > 550 for aspirin. Renal function was classified based on the estimated glomerular filtration rate (eGFR), and dipstick proteinuria was defined as ≥30 mg/dl of albumin detected on a spot analysis. All cause mortality, readmissions, and cardiac catheterizations were reviewed over 520 days. In patients on clopidogrel (n = 106), DP was associated with HTPR, independent of eGFR, diabetes mellitus, smoking or use of proton pump inhibitor (AOR = 4.76, p = 0.03). In patients with acute coronary syndromes, HTPR was associated with more cardiac catheterizations (p = 0.009) and readmissions (p = 0.032), but no differences in in-stent thrombosis or re-stenosis were noted in this cohort. In patients on aspirin (n = 155), no associations were seen between DP and HTPR. However, all cause mortality was significantly higher with HTPR in this group (p = 0.038). In this cohort, DP is an independent predictor of HTPR in patients on clopidogrel, but not aspirin, admitted to the hospital for MACE.

Variability in on-treatment platelet reactivity explained by CYP2C19*2 genotype is modest in clopidogrel pretreated patients undergoing coronary stenting

BackgroundAn inadequate response to clopidogrel is mainly attributable to the variable formation of its active metabolite. The CYP2C19*2 loss-of-function polymorphism leads to reduced generation of the active metabolite and is,...

Impact of concomitant use of proton-pump inhibitors and thienopyridine derivatives on the antiplatelet effects

Although there has been an intense debate whether concomitant use of proton-pump inhibitors (PPIs) attenuates the antiplatelet effects of thienopyridine derivatives, the drug-drug interaction remains unclear in Japanese patients with coronary artery disease. Platelet function test was performed in 461 patients who were scheduled for or had undergone stent implantation, treated with 100mg/day of aspirin and a thienopyridine (200mg/day of ticlopidine or 75 mg/day of clopidogrel) for at least 14 days. Adenosine diphosphate-induced platelet aggregation was evaluated with screen filtration pressure method, and the upper quartile of high platelet reactivity was defined as high on-treatment platelet reactivity (HPR). PPI use was at physician's discretion. Patients taking a thienopyridine plus a PPI (n=166) were older and had a higher incidence of acute coronary syndromes on admission compared with patients taking a thienopyridine without a PPI (n=295). The rate of HPR was higher in patients taking a thienopyridine plus a PPI than in patients taking a thienopyridine without a PPI (31% vs 21%, p=0.01). On multivariate logistic regression analysis, independent predictors of HPR were concomitant PPI use [odds ratio (OR): 1.66, 95% confidence interval (CI): 1.03-2.68], diabetes mellitus (OR: 1.76, CI: 1.11-2.81), and calcium channel blockers use (OR: 1.93, CI: 1.18-3.18). However, there was no significant difference in the rate of extremely high platelet reactivity [58 patients (12.5%) with PATI<4.0 μM] between patients treated with a thienopyridine plus a PPI and those without a PPI (14% vs 11%, NS). HPR was frequently observed in Japanese patients treated with thienopyridines plus PPIs compared to those without PPIs. Further prospective studies are needed to estimate the risk of adverse cardiovascular events associated with concomitant use of PPIs and thienopyridines.

Cilostazol attenuates on-treatment platelet reactivity in patients with CYP2C19 loss of function alleles receiving dual antiplatelet therapy: a genetic substudy of the CILON-T randomised controlled trial

ObjectiveTo evaluate whether the addition of cilostazol to dual antiplatelet therapy (DAT, aspirin plus clopidogrel) can attenuate clopidogrel on-treatment platelet reactivity (OPR) in patients with the CYP2C19 loss-of-function (LOF) allele.MethodsIn...

The cytochrome 2C19*2 and *3 alleles attenuate response to clopidogrel similarly in East Asian patients undergoing elective percutaneous coronary intervention

Introduction Carriage of CYP2C19*2 allele is associated with diminished platelet response to clopidogrel. However, the loss-of-function impact of CYP2C19*3 allele on antiplatelet effect of clopidogrel has not been definitely verified. We conducted this study to compare decreased response to clopidogrel according to carriage of CYP2C19*2 vs. *3 allele. Materials and methods The study included 190 consecutive Korean patients undergoing elective percutaneous coronary intervention. Light transmittance aggregometry and the VerifyNow P2Y 12 assay were used to assess platelet reactivity (PR) at least 12 hours after 300-mg loading of clopidogrel. The cutoff of high on-treatment PR (HPR) was defined as 5 μmol/L ADP-induced PR > 50%. CYP2C19 genotype was analyzed by the SNaPshot method . Results Carriers of at least one CYP2C19 variant allele were 115 patients (60.5%), and allelic frequency of CYP2C19*2 and *3 was 30.3% and 6.8%, respectively. PR and the rate of HPR increased proportionally according to the number of CYP2C19 variant allele . Carriage of CYP2C19 variant allele was an only independent predictor of HPR in multivariate analysis. When we compare the effect of allelic carriage, there were no significant differences in platelet measures and the rate of HPR between carriers of CYP2C19*2 and/or *3 allele(s) whether they were intermediate or poor metabolizers. Conclusion Carriage of CYP2C19*3 allele is associated with diminished antiplatelet effect of clopidogrel, which may be as potent as the loss-of-function effect of CYP2C19*2 allele.