The prognostic impact of high on-treatment platelet reactivity with aspirin or ADP receptor antagonists: systematic review and meta-analysis

Clopidogrel Resistance Is Associated With DNA Methylation of Genes From Whole Blood of Humans

Antiplatelet therapy has become a cornerstone in the treatment of coronary heart disease (CHD). However, due to high-residual-platelet-reactivity, clopidogrel resistance (CR) is a common phenomenon, and it is rarely known about the relationship between CR and epigenetic changes. This study compared the whole genomic methylation patterns of blood samples from patients with CR (n = 6) and non-CR (n = 6) with the Human Methylation 850K BeadChip assay. We explored differentially methylated CpG sites, genes, and pathways using bioinformatics profiling. The CR and control groups showed significantly different DNA methylation at 7,098 sites, with 979 sites showing hypermethylation and 6,119 sites showing hypomethylation. The pyrosequencing method was used to validate four differentially methylated CpG loci (cg23371584, cg15971518, cg04481923, cg22507406), confirming that DNA methylation was associated with the risk of CR (30 CR vs. 30 non-CR). The relative mRNA expression of the four genes (BTG2, PRG2, VTRNA2-1, PER3) corresponding to the loci above was also associated with CR, suggesting that alterations in DNA methylation may affect the expression of these four genes, eventually resulting in CR. Additionally, differentially methylated sites are partially related to genes and pathways that play key roles in process of circadian entrainment, insulin secretion, and so on. Hence, the mechanism and biological regulation of CR might be reflected through these epigenetic alterations, but future research will need to address the causal relationships.

Long versus short dual antiplatelet therapy in acute coronary syndrome patients treated with prasugrel or ticagrelor and coronary revascularization: Insights from the RENAMI registry

Introduction

The benefits of short versus long-term dual antiplatelet therapy (DAPT) based on the third generation P2Y12 antagonists prasugrel or ticagrelor, in patients with acute coronary syndromes treated with percutaneous coronary intervention remain to be clearly defined due to current evidences limited to patients treated with clopidogrel.

Methods

All acute coronary syndrome patients from the REgistry of New Antiplatelets in patients with Myocardial Infarction (RENAMI) undergoing percutaneous coronary intervention and treated with aspirin, prasugrel or ticagrelor were stratified according to DAPT duration, that is, shorter than 12 months (D1 group), 12 months (D2 group) and longer than 12 months (D3 group). The three groups were compared before and after propensity score matching. Net adverse clinical events (NACEs), defined as a combination of major adverse cardiac events (MACEs) and major bleedings (including therefore all cause death, myocardial infarction and Bleeding Academic Research Consortium (BARC) 3–5 bleeding), were the primary end points, MACEs (a composite of all cause death and myocardial infarction) the secondary one. Single components of NACEs were co-secondary end points, along with BARC 2–5 bleeding, cardiovascular death and stent thrombosis.

Results

A total of 4424 patients from the RENAMI registry with available data on DAPT duration were included in the model. After propensity score matching, 628 patients from each group were selected. After 20 months of follow up, DAPT for 12 months and DAPT for longer than 12 months significantly reduced the risk of NACE (D1 11.6% vs. D2 6.7% vs. D3 7.2%, p = 0.003) and MACE (10% vs. 6.2% vs. 2.4%, p < 0.001) compared with DAPT for less than 12 months. These differences were driven by a reduced risk of all cause death (7.8% vs. 1.3% vs. 1.6%, p < 0.001), cardiovascular death (5.1% vs. 1.0% vs. 1.2%, p < 0.0001) and recurrent myocardial infarction (8.3% vs. 5.2% vs. 3.5%, p = 0.002). NACEs were lower with longer DAPT despite a higher risk of BARC 2–5 bleedings (4.6% vs. 5.7% vs. 6.2%, p = 0.04) and a trend towards a higher risk of BARC 3–5 bleedings (2.4% vs. 3.3% vs. 3.9%, p = 0.06). These results were not consistent for female patients and those older than 75 years old, due to an increased risk of bleedings which exceeded the reduction in myocardial infarction.

Conclusion

In unselected real world acute coronary syndrome patients treated with percutaneous coronary intervention, DAPT with prasugrel or ticagrelor prolonged beyond 12 months markedly reduces fatal and non-fatal ischaemic events, offsetting the increased risk deriving from the higher bleeding risk. On the contrary, patients >75 years old and female ones showed a less favourable risk–benefit ratio for longer DAPT due to excess of bleedings.

Factors associated with platelet reactivity during dual antiplatelet therapy in patients with diabetes after acute coronary syndrome

Antiplatelet drugs are prescribed without considering the diabetic status of the patient. The objective of the current investigation was to determine the impact of clinical factors, CYP4F2 enzyme and 20-hydroxyeicosatetraenoic acid (20-HETE) concentrations on high on-treatment platelet reactivity in patients with diabetes treated with antiplatelet drugs following acute coronary syndromes. A total of 667 patients were included in the study. Dual antiplatelet drug loading dosages with aspirin (300 mg) and ticagrelor (180 mg) or clopidogrel (600 mg) were prescribed to all the studied patients. Testing of platelet aggregation was performed the day after loading antiplatelet drug dosages. Platelet aggregation test was done according to the classical Born method. Multivariate binary regression analysis demonstrated that insulin use and higher 20-HETE concentration increased the odds of high on-treatment platelet reactivity during the initiation of antiplatelet drug therapy (OR: 3.968, 95% CI: 1.478-10.656, p = 0.006 and OR: 1.139, 95% CI: 1.073-1.210, respectively, p < 0.001). Ticagrelor use decreased the odds of developing high on-treatment platelet reactivity (OR: 0.238, 95% CI: 0.097-0.585, p = 0.002). Data from this study revealed that high on-treatment platelet reactivity during dual antiplatelet therapy in patients with diabetes may depend on such factors as insulin prescription and 20-HETE concentration.

A brief review on resistance to P2Y12 receptor antagonism in coronary artery disease

Background

Platelet inhibition is important for patients with coronary artery disease. When dual antiplatelet therapy (DAPT) is required, a P2Y₁₂-antagonist is usually recommended in addition to standard aspirin therapy. The most used P2Y₁₂-antagonists are clopidogrel, prasugrel and ticagrelor. Despite DAPT, some patients experience adverse cardiovascular events, and insufficient platelet inhibition has been suggested as a possible cause. In the present review we have performed a literature search on prevalence, mechanisms and clinical implications of resistance to P2Y₁₂ inhibitors.

Methods

The PubMed database was searched for relevant papers and 11 meta-analyses were included. P2Y₁₂ resistance is measured by stimulating platelets with ADP ex vivo and the most used assays are vasodilator stimulated phosphoprotein (VASP), Multiplate, VerifyNow (VN) and light transmission aggregometry (LTA).

Discussion/conclusion

The frequency of high platelet reactivity (HPR) during clopidogrel therapy is predicted to be 30%. Genetic polymorphisms and drug-drug interactions are discussed to explain a significant part of this inter-individual variation. HPR during prasugrel and ticagrelor treatment is estimated to be 3–15% and 0–3%, respectively. This lower frequency is explained by less complicated and more efficient generation of the active metabolite compared to clopidogrel. Meta-analyses do show a positive effect of adjusting standard clopidogrel treatment based on platelet function testing. Despite this, personalized therapy is not recommended because no large-scale RCT have shown any clinical benefit. For patients on prasugrel and ticagrelor, platelet function testing is not recommended due to low occurrence of HPR.

Update on pathological platelet activation in coronary thrombosis

Although coronary thrombosis (CT) is integral to cardiovascular outcomes, the underlying pathophysiological mechanisms remain unclear. CT may occur in case of atherosclerotic plaque erosion/rupture, or even after stenting implantation. Platelets (PLT) activation is the keystone of atherothrombosis and depends on many dysregulated elements, including endothelial dysfunction, oxidized lipoproteins, and immune response. Besides the classical view of PLT as an effector of hemostatic response, a new repertoire of PLT activities is emerging. PLT lipidome oxidation is a self-maintaining process which promotes PLT reactivity, coagulation cascade, and inflammatory cell activation. PLT-innate immune cell interaction is also sustained by neutrophil extracellular traps and NLRP3 inflammasome pathways. Other noteworthy emerging mechanisms are implicated in the crosstalk between PLT and surrounding cells. Especially, microvesicles (MVs) released from PLT may extend their signaling network far beyond the classical cell-cell interactions. Moreover, the recognition of noncoding RNA in PLT MVs introduce another layer of complexity in terms of intercellular signaling by a direct regulation of messenger RNA profile and gene expression in the recipient cells. The aim of this narrative review is to update the recent advance in CT and intracoronary stent thrombosis, including causal factors and potential translation of experimental evidence into the clinical setting.

Thromboxane Formation Assay to Identify High On-Treatment Platelet Reactivity to Aspirin

Platelet inhibition by aspirin is indispensable in the secondary prevention of cardiovascular events. Nevertheless, impaired aspirin antiplatelet effects (high on-treatment platelet reactivity [HTPR]) are frequent. This is associated with an enhanced risk of cardiovascular events. The current gold standard to evaluate platelet hyper-reactivity despite aspirin intake is the light-transmittance aggregometry (LTA). However, pharmacologically, the most specific test is the measurement of arachidonic acid (AA)-induced thromboxane (TX) B2 formation. Currently, the optimal cut-off to define HTPR to aspirin by inhibition of TX formation is not known. Therefore, in this pilot study, we aimed to calculate a TX formation cut-off value to detect HTPR defined by the current gold standard LTA. We measured platelet function in 2,507 samples. AA-induced TX formation by ELISA and AA-induced LTA were used to measure aspirin antiplatelet effects. TX formation correlated nonlinearly with the maximum of aggregation in the AA-induced LTA (Spearman's rho R = 0.7396; 95% CI 0.7208-0.7573, p < 0.0001). Receiver operating characteristic analysis and Youden's J statistics revealed 209.8 ng/mL as the optimal cut-off value to detect HTPR to aspirin with the TX ELISA (area under the curve: 0.92, p < 0.0001, sensitivity of 82.7%, specificity of 90.3%). In summary, TX formation ELISA is reliable in detecting HTPR to aspirin. The calculated cut-off level needs to be tested in trials with clinical end points.

New single-nucleotide polymorphisms associated with differences in platelet reactivity and their influence on survival in patients with type 2 diabetes treated with acetylsalicylic acid: an observational study

AIMS

Genetic polymorphisms may contribute to platelet reactivity in diabetic patients; however, the information on their influence on long-term antiplatelet therapy is lacking. Our aim was to evaluate the role of previously described genetic variants and platelet reactivity on risk of all-cause mortality and cardiovascular events.

METHODS

Blood samples were obtained from 303 Caucasian patients. Genome-wide genotyping was performed using Illumina Human Omni 2.5-Quad microarrays, and individual genotyping of selected SNPs was performed using a custom Sequenom iPLEX assay in conjunction with the Mass ARRAY platform. Platelet reactivity was measured with VerifyNow Aspirin Assay and PFA-100 Assay. Univariate and multivariate Cox regression analyses were performed to determine the impact of genetic variants and platelets reactivity on risk of all-cause mortality and cardiovascular events.

RESULTS

Among the 237 patients included in the follow-up, death from any cause occurred in 34 (14.3%) patients and cardiovascular events occurred in 51 (21.5%) patients within a median observation time of 71 months (5.9 years). In univariate analyses, significant association in the presence of minor alleles in TXBA2R (rs1131882) with primary (HR 2.54, 95% CI 1.15-5.60, p = 0.021) and secondary endpoint (HR 2.06, 95% CI 1.06-4.04, p = 0.034) was observed. In addition, multivariate analyses revealed the impact of this polymorphism on primary (HR 2.34, 95% CI 1.09-5.00, p = 0.029) and secondary endpoint (HR 1.89, 95% CI 1.00-3.57, p = 0.048).

CONCLUSIONS

Results of the study demonstrate for the first time an association between genetic polymorphism within TXBA2R gene encoding platelet's surface receptor and long-term survival of diabetic patients treated with ASA.

Impact of Cytochrome P450 2C19*2 and *3 on Clopidogrel Loading Dose in Saudi Patients with Acute Coronary Syndrome

BACKGROUND

Emerging evidence shows that clopidogrel is greatly affected by nonfunctioning alleles measured by P2Y12 or platelet reactivity units (PRU). Cardiac events during short in-hospital stays have been inconclusively suggested as the main causes of discrepancies.

OBJECTIVES

Evaluate the impact of CYP2C19 allele *2 and allele *3 on PRU and the potential clinical consequences of such interaction. To establish a rough estimation for the safe PRU limits for short inhospital stay following PCI.

METHOD

A short-term experimental study was conducted with 90 patients who underwent coronary angioplasty with drug eluting stents at the Prince Sultan Cardiac Center, Buraidah. All the patients received an initial loading dose of 300 mg clopidogrel, followed by 75 mg daily. Blood samples were used for DNA extraction for cytochrome P450 (CYP) and realtime polymerase chain reaction (PCR) was used for genotyping. PRU and inhibition rate were tested by Verifynow®. All in-hospital cardiac events were recorded until patients were discharged.

RESULTS

Genotypes 1/1, 2/2, and 1/2 were expressed by 60, 28, and two patients (67, 32, and 3%), respectively. The PRU of the female patients was significantly higher than that of the male patients was (255.6 ± 68.8 and 177.7 ± 66.6, p = 0.000, respectively). There was no significant difference in PRUs (193 ± 79 and 212 ±55.4, respectively, p = 0.349), nor inhibition (17.9 ± 18.80 and 13.88 ± 11.5, p = 0.135) in wild and resistant variants, respectively. We only reported one cardiac in-thrombosis events.

CONCLUSION

Genotype differences may not explain variations in the PRU of patients during short-term in-hospital stays. Although it is difficult to confirm, 117-267 units may be a safe PRU range for such patients, with emphasis on attaining higher PRU values in females.