Diversity of platelet function and genetic polymorphism in clopidogrel-treated Chinese patients

Influence of genetic polymorphisms in P2Y12 receptor signaling pathway on antiplatelet response to clopidogrel in coronary heart disease

BACKGROUNDS

Remarkable interindividual variability in clopidogrel response is observed, genetic polymorphisms in P2RY12 and its signal pathway is supposed to affect clopidogrel response in CHD patients.

METHODS

539 CHD patients treated with clopidogrel were recruited. The platelet reaction index (PRI) indicated by VASP-P level were detected in 12-24 h after clopidogrel loading dose or within 5-7 days after initiation of maintain dose clopidogrel. A total of 13 SNPs in relevant genes were genotyped in sample A (239 CHD patients). The SNPs which have significant differences in PRI will be validated in another sample (sample B, 300 CHD patients).

RESULTS

CYP2C19*2 increased the risk of clopidogrel resistance significantly. When CYP2C19*2 and CYP2C19*3 were considered, CYP2C19 loss of function (LOF) alleles were associated with more obviously increased the risk of clopidogrel resistance; P2RY12 rs6809699C > A polymorphism was also associated with increased risk of clopidogrel resistance (AA vs CC: P = 0.0398). This difference still existed after stratification by CYP2C19 genotypes. It was also validated in sample B. The association was also still significant even in the case of stratification by CYP2C19 genotypes in all patients (sample A + B).

CONCLUSION

Our data suggest that P2RY12 rs6809699 is associated with clopidogrel resistance in CHD patients. Meanwhile, the rs6809699 AA genotype can increase on-treatment platelet activity independent of CYP2C19 LOF polymorphisms.

Viscoelastic Hemostatic Assays and Platelet Function Testing in Patients with Atherosclerotic Vascular Diseases

Platelets play crucial role in acute vascular atherosclerotic diseases, including myocardial infarction and stroke. Additionally, platelet aggregation is a key target of antiplatelet agents, forming the keystone of pharmacotherapy of various atherosclerotic cardiovascular diseases. Thromboelastography and thromboelastometry, representing currently available viscoelastic hemostatic assays (VHA), are designed as whole blood, real-time analyzers of clot formation and clot resolution. These assays could, in theory, overcome some limitations of currently available platelet function testing assays. This article reviews the current experience with the use of VHA for platelet function testing and for monitoring of the response to antiplatelet therapy.

Pharmacogenomic considerations for antiplatelet agents: the era of precision medicine in stroke prevention and neurointerventional practice

Antiplatelet drugs are widely utilized in the setting of primary stroke prevention, secondary stroke prevention, and neuroendovascular device-related stroke prevention. These medications are effective in general, although significant variability in drug activity exists between patients. Although this variation may be related in part to a multitude of factors, a growing body of evidence suggests that individual genotypes are a main contributor. The PharmGKB database was mined to prioritize genetic variants with potential clinical relevance for response to aspirin, clopidogrel, prasugrel, and ticagrelor. Although variants were reported for all drugs, the highest level of evidence was found in cytochrome P450 (CYP450) genotype variation related to clopidogrel response. Individual genetic influences have an impact on the pharmacodynamics of antiplatelet agents. Current clinical practice for stroke prevention is primarily empiric or guided by functional assays; however, there now exists a third potential pathway to base treatment decisions: genotype-guided treatment.

The Management of Heavy Menstrual Bleeding After Percutaneous Coronary Intervention in a Woman of Reproductive Age

Heavy menstrual bleeding (HMB), previously known as menorrhagia, is in place with heavy flow and longer lasting days of bleeding during menstrual period, sequentially leading to anemia. We reported a rare case of HMB in a 33-year-old patient after percutaneous coronary intervention (PCI), who presented with acute coronary syndromes (ACS), uremia and systemic lupus erythematosus before PCI. This patient received three times of hemodialysis weekly (Monday, Wednesday, and Friday). On the next day after PCI, this patient began to have menstruation. On the fifth day of menstruation, the patient complained of HMB and physical discomfort, with an urgent need for consultation of gynecologist. After gynecologist consultation, this patient was under oxytocin treatment. However, 2 days of oxytocin treatment did not significantly improve HMB. Afterward, the menstrual volume of patients was significantly reduced on eighth day of menstruation after once therapy of testosterone propionate and norethindrone. Regarding the reasons of HMB, heparin in hemodialysis and antiplatelet drugs utilized (aspirin and clopidogrel) after PCI may be contributors to the HMB. In addition, uterine myoma, cervical canal cyst, renal insufficiency and CYP2C19^∗2 heterozygous are also possible contributors to HMB. There is no such case of whom had HMB in reproductive age with ACS, uremia and systemic lupus erythematosus under hemodialysis and antiplatelet therapy. More clinical safety data on HMB of reproductive age women who are under antithrombotic therapy are required.

Associations between P2RY12 gene polymorphisms and risks of clopidogrel resistance and adverse cardiovascular events after PCI in patients with acute coronary syndrome

Clopidogrel resistance in patients with acute coronary syndrome (ACS) is one of the key causes of recurrent cardiovascular disease (CVD) events after percutaneous coronary intervention (PCI). Clopidogrel targets the platelet membrane receptor P2RY12 to inhibit platelet aggregation via adenosine diphosphate (ADP). This study aimed to investigate the relationships between P2RY12 polymorphisms and the risk of clopidogrel resistance and adverse CVD events after PCI. From January 2015 to December 2014, patients who had been diagnosed with ACS undergoing PCI and treated with clopidogrel were recruited for this prospective cohort study (N = 498). Data regarding demographics, medication intake, and ACS lesion were recorded, and whole blood samples were collected for biochemical tests, ADP-induced platelet aggregation ratio detection, and P2RY12 genotyping. P2RY12 genotyping was performed by polymerase chain reaction. The left ventricular ejection fraction was calculated by echocardiography. After 3 to 12 months of follow-up, data regarding any adverse CVD event or death were recorded. The allele frequencies for the T variation alleles in C34T and G52T of P2RY12 were 20.3% and 11.6%, respectively. Patients with T variations at C34T or G52T of P2RY12 had a significantly higher risk of clopidogrel resistance (C34T: P < 0.001; G52T: P = 0.003) and total cardiovascular events (C34T: P = 0.013; G52T: P = 0.018) compared to those with the wild-type genotype. Moreover, multivariable logistic regression showed that patients with the T variations in C34T (odds ratio [OR]: 2.89 (95% confidence interval [CI]: 1.48-5.64), P = 0.002) and G52T (OR: 3.68 [95% CI: 1.71-7.92], P = 0.001) also had a significantly higher risk of clopidogrel resistance. Also, the T variations in C34T (OR: 2.68 [95% CI: 1.07-6.73], P = 0.035) and G52T (OR: 5.64 [95% CI: 1.52-20.88], P = 0.010) significantly increased the risk of post-PCI CVD events after accounting for confounding factors. The P2RY12 gene polymorphisms C34T and G52T were significantly associated with a higher risk of clopidogrel resistance and sequential cardiovascular events in Chinese ACS patients after PCI.

Association between CYP3A5 polymorphisms and the risk of adverse events in patients undergoing clopidogrel therapy: Meta-analysis

INTRODUCTION

We wished to explore the relationship between CYP3A5 polymorphisms and adverse events in patients undergoing clopidogrel therapy.

METHODS

A Boolean search of the PubMed, EMbase, OVID and Cochrane Library databases was conducted in April 2016. The primary outcome was major adverse cardiovascular events (MACE). The secondary outcome was bleeding events and resistance to the effects of clopidogrel. The CYP3A5 polymorphism was classified into three types: wild-type (AA), heterozygote (AG) and homozygous mutant (GG). We estimated pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) using the Mantel-Haenszel model.

RESULTS

Twelve studies involving 8284 patients were eligible for our meta-analysis. CYP3A5 polymorphisms had no obvious influence on MACE (AA+AG vs. GG: OR=1.032, 95% CI=0.583-1.824, p=0.915; AA vs. AG+GG: 1.415, 0.393-5.094, 0.595). There was no significant relationship between CYP3A5 polymorphisms and bleeding (GG vs. AA+AG: OR=0.798, 95% CI=0.370-1.721, p=0.565) or clopidogrel resistance (AA+AG vs. GG: 1.009, 0.685-1.488, 0.963; AA vs. AG+GG, 0.618, 0.368-1.039, 0.069).

CONCLUSION

No significant correlation was found between CYP3A5 polymorphisms and adverse events due to clopidogrel therapy.