Platelet reactivity in response to aspirin and ticagrelor in African-Americans and European-Americans

Early detection of resistance to dual antiplatelet therapy in patients who have undergone percutaneous coronary intervention using the VerifyNow test and associated factors

Resistance to dual antiplatelet therapy (DAPT), including aspirin and clopidogrel, in patients who have undergone percutaneous coronary intervention (PCI) leads to the inability to prevent thrombotic complications. The present study aimed to evaluate early resistance to aspirin and clopidogrel in patients following PCI using the VerifyNow test and associated factors. A total of 50 patients diagnosed with acute coronary syndromes (ACS) who underwent emergency PCI and received DAPT were recruited in the present study. The detection of resistance to aspirin and clopidogrel was performed using the VerifyNow system. Resistance to aspirin was determined with VerifyNow Aspirin >550 aspirin reaction units (ARU). Resistance to clopidogrel was determined with VerifyNow P2Y12 >208 P2Y12 reaction units (PRU). The resistance rate to aspirin was 14%, while the resistance rate to clopidogrel was higher, at 34%. There were 2 patients with resistance to aspirin and clopidogrel (4%). Univariable logistic regression analysis revealed that diabetes, the use of β-blockers, and low levels of hemoglobin and hematocrit were associated with resistance to clopidogrel. Following multivariable logistic regression analysis, only the use of β-blockers was truly associated with resistance to clopidogrel. On the whole, the results of the present study may also prove to be helpful in the selection of therapeutic drugs for patients undergoing PCI and who are diagnosed with ACS.

Impact of aspirin dose according to race in secondary prevention of atherosclerotic cardiovascular disease: a secondary analysis of the ADAPTABLE randomised controlled trial

OBJECTIVES

To evaluate whether the effectiveness and safety of low (81 mg daily) versus high-dose (325 mg daily) aspirin is consistent across races among patients with established atherosclerotic cardiovascular disease (ASCVD).

DESIGN

A secondary analysis of the randomised controlled trial ADAPTABLE was performed.

SETTING

The study was conducted in 40 centres and one health plan participating in the National Patient-Centred Clinical Research Network (PCORnet) in the USA.

PARTICIPANTS

Among 15 076 participants with established ASCVD, 14 096 had self-reported race available and were included in the analysis. Participants were divided according to self-reported race as Black (n=1311, 9.3%), White (n=11 990, 85.1%) or other race (n=795, 5.6%).

INTERVENTIONS

Participants were randomised to open-label daily aspirin doses of 81 mg versus 325 mg in a 1:1 ratio for a median of 26.2 months.

PRIMARY AND SECONDARY OUTCOMES MEASURES

The primary effectiveness endpoint was a composite of death from any cause, hospitalisation for myocardial infarction or hospitalisation for stroke. The primary safety endpoint was hospitalisation for bleeding requiring blood product transfusion.

RESULTS

Estimated cumulative incidence of the primary effectiveness endpoint at median follow-up with the 81 mg and the 325 mg daily doses were 6.70% and 7.12% in White participants (adjusted HR: 1.00 [95% CI: 0.88 to 1.15]); 12.27% and 10.69% in Black participants (adjusted HR: 1.40 [95% CI: 1.02 to 1.93]); and 6.88% and 7.69% in other participants (adjusted HR: 0.86 [95% CI: 0.54 to 1.39]) (p-interaction=0.12), respectively. There was no significant interaction between self-reported race and assigned aspirin dose regarding the secondary effectiveness and the primary safety endpoints.

CONCLUSION

Race is not an effect modifier on the impact of aspirin dosing on effectiveness and safety in patients with established ASCVD. In clinical practice, treatment decisions regarding aspirin dose in secondary prevention of ASCVD should not be influenced by race.

TRIAL REGISTRATION NUMBER

NCT02697916.

Heterogeneity of platelets and their responses

There has been increasing recognition of heterogeneity in blood platelets and their responses, particularly in recent years, where next-generation technologies and advanced bioinformatic tools that interrogate "big data" have enabled large-scale studies of RNA and protein expression across a growing list of disease states. However, pioneering platelet biologists and clinicians were already hypothesizing upon and investigating heterogeneity in platelet (and megakaryocyte) activity and platelet metabolism and aggregation over half a century ago. Building on their foundational hypotheses, in particular Professor Marian A. Packham's pioneering work and a State of the Art lecture in her memoriam at the 2023 International Society on Thrombosis and Haemostasis Congress by Anandi Krishnan, this review outlines the key features that contribute to the heterogeneity of platelets between and within individuals. Starting with important epidemiologic factors, we move stepwise through successively smaller scales down to heterogeneity revealed by single-cell technologies in health and disease. We hope that this overview will urge future scientific and clinical studies to recognize and account for heterogeneity of platelets and aim to apply methods that capture that heterogeneity. Finally, we summarize other exciting new data presented on this topic at the 2023 International Society on Thrombosis and Haemostasis Congress.

Four-Week Supplementation of Water-Soluble Tomato Extract Attenuates Platelet Function in Chinese Healthy Middle-Aged and Older Individuals: A Randomized, Double-Blinded, and Crossover Clinical Trial

Background and Aims

Platelets are linked to atherosclerotic development and pathological thrombosis. Single dose of water-soluble tomato extract (WTE) which is a natural extraction can exert anti-platelet effects after 3 or 7 h in British healthy people. However, the effects of WTE supplementation on platelet function in Chinese healthy middle-aged and older individuals have not been studied, and the effects or safety of 4-week WTE supplementation also remain unclear. The present study aims to determine the effects of WTE on platelet function, and explore the safety of 4-week WTE supplementation in Chinese healthy middle-aged and older individuals.

Methods

A randomized, double-blinded, and crossover clinical trial was conducted. Firstly, 105 individuals were randomly divided into two groups that received WTE (150 mg/day) or placebo for 4 weeks. Then, after a washout period of 2 weeks, two groups exchanged groups and continued for another 4-week intervention. Platelet aggregation, P-selectin, activated GPIIbIIIa, plasma platelet factor 4 (PF4), β-thromboglobulin (β-TG), and thromboxane B₂ (TXB₂) were tested at baseline, 4, 6, and 10 weeks.

Results

Compared with the placebo group, 150 mg/day WTE supplement for 4 weeks significantly reduced ADP-induced or collagen-induced platelet aggregation (−10.8 ± 1.8 or −3.9 ± 1.5%, P < 0.05), ADP-induced or collagen-induced platelet P-selectin expression (−6.9 ± 1.5 or −6.6 ± 1.3%, P < 0.05), ADP-induced or collagen-induced activated GPIIbIIIa (−6.2 ± 2.0 or −3.8 ± 2.0%, P < 0.05). Besides, 4-week intervention of 150 mg WTE per day also resulted in significant reductions in plasma PF4 (−120.6 ± 33.2 ng/mL, P < 0.05) and β-TG (−129.7 ± 27.5 ng/mL, P < 0.05) and TXB₂ (−42.0 ± 4.0 ng/mL, P < 0.05), while had no effects on coagulation function and liver or renal function. Interestingly, 2-week washout period is enough to reverse the inhibitory effect of 4-week WTE supplementation on platelet function.

Conclusion

WTE supplementation for 4 weeks could moderately reduce platelet activation, aggregation, and granule secretion in Chinese healthy middle-aged and older individuals, and these effects are safe. After 2-week washout period, the inhibitory effect of 4-week WTE on platelet function can be eliminated.

Clinical Trial Registration

[http://www.chictr.org.cn/], identifier [ChiCTR-POR-17012927].

Effect of Genetic Polymorphism Including NUP153 and SVEP1 on the Pharmacokinetics and Pharmacodynamics of Ticagrelor in Healthy Chinese Subjects

BACKGROUND AND OBJECTIVE

The search for potential gene loci that affect the pharmacodynamics and pharmacokinetics of ticagrelor is a matter of broad clinical interest. The objective of this study was to investigate the effect of genetic polymorphisms on the pharmacokinetics and pharmacodynamics of ticagrelor in healthy Chinese subjects.

METHODS

This is a multi-center study in China, including three hospitals from Beijing, Nanchang, and Changsha. Healthy Chinese subjects aged 18-45 years with unknown genotypes were included. All subjects received a single oral dose of 90 mg of ticagrelor. Platelet aggregation and the area under the concentration-time curve for ticagrelor and its major active metabolite in plasma samples were assessed. Genome-wide association studies and candidate gene association analysis related to ticagrelor were performed.

RESULTS

One hundred and seventy-five native Chinese subjects were enrolled and completed the study. According to the p value, the threshold of ticagrelor population was 6.57 × 10^-7 (0.05/76106), one single-nucleotide polymorphism chr6:17616513 of gene NUP153 (p = 2.03 × 10^-7) related to the area under the concentration-time curve for plasma concentration at time zero versus the last measurable timepoint, and one single nucleotide polymorphism rs17204533 of gene SVEP1 (p = 3.96 × 10^-7) related to P2Y12 reaction unit_12h of ticagrelor was identified. In addition, L1TD1, CETP, CLEC2A, CHSY1, PDZRN3, CTU2, PIEZO1, APOBEC1, SEMA6A, KAZN, and FASN polymorphisms might influence the pharmacokinetics of ticagrelor, while PARP10, TRIB1, CYP2C19, and UGT2B7 might affected its pharmacodynamics.

CONCLUSIONS

Genetic variation affects the pharmacokinetics and pharmacodynamics of ticagrelor in healthy individuals. The detection of NUP153, SVEP1 gene variation will be helpful for pharmacodynamic prediction and evaluation, and the regulation of these genes may be the target of new drug development. Further studies are required to confirm the results and explore whether these single-nucleotide polymorphisms are associated only with platelet activity or also with cardiovascular events and all-cause mortality.

CLINICAL TRIAL REGISTRATION

NCT03161002.

OUP accepted manuscript

AIMS

Gene expression biosignatures may hold promise to individualize antiplatelet therapy in conjunction with current guidelines and risk scores. The Aspirin Response Signature (ARS) score is comprised of a weighted sum of correlated, pro-thrombotic gene transcripts measured in whole blood. In prior work where volunteers were exposed to aspirin 325 mg daily, higher ARS score was associated with lower platelet function; separately, in a clinical cohort of patients, higher ARS scores were associated with increased risk of adverse cardiovascular events. To better understand this apparent paradox, we measured ARS gene expression and score in volunteers to determine aspirin dose-response and ticagrelor relationships with ARS score and separately in patients to assess whether ARS is associated with incident bleeding.

METHODS AND RESULTS

Blood samples were collected from volunteers (N = 188) who were exposed to 4 weeks of daily aspirin 81 mg, daily aspirin 325 mg, and/or twice-daily ticagrelor 90 mg. ARS scores were calculated from whole blood RNA qPCR, and platelet function and protein expression were assessed in platelet-rich plasma. In mixed linear regression models, aspirin 81 mg exposure was not associated with changes in ARS gene expression or score. Aspirin 325 mg exposure resulted in a 6.0% increase in ARS gene expression (P = 7.5 × 10-9 vs. baseline, P = 2.1 × 10-4 vs. aspirin 81 mg) and an increase in expression of platelet proteins corresponding to ARS genes. Ticagrelor exposure resulted in a 30.7% increase in ARS gene expression (P < 1 × 10-10 vs. baseline and each aspirin dose) and ARS score (P = 7.0 × 10-7 vs. baseline, P = 3.6 × 10-6 and 5.59 × 10-4 vs. aspirin 81 and 325 mg, respectively). Increases in ARS gene expression or score were associated with the magnitude of platelet inhibition across agents. To assess the association between ARS scores and incident bleeding, ARS scores were calculated in patients undergoing cardiac catheterization (N = 1421), of whom 25.4% experienced bleeding events over a median 6.2 years of follow-up. In a Cox model adjusting for demographics and baseline antithrombotic medication use, patients with ARS scores above the median had a higher risk of incident bleeding [hazard ratio 1.26 (95% CI 1.01-1.56), P = 0.038].

CONCLUSIONS

The ARS is an Antiplatelet Response Signature that increases in response to greater platelet inhibition due to antiplatelet therapy and may represent a homeostatic mechanism to prevent bleeding. ARS scores could inform future strategies to prevent bleeding while maintaining antiplatelet therapy's benefit of ischaemic cardiovascular event protection.

Racial and ethnic disparities in coronary, vascular, structural, and congenital heart disease

Cardiovascular disease (CVD) remains the leading cause of death in the United States. However, percutaneous interventional cardiovascular therapies are often underutilized in Blacks, Hispanics, and women and may contribute to excess morbidity and mortality in these vulnerable populations. The Society for Cardiovascular Angiography and Interventions (SCAI) is committed to reducing racial, ethnic, and sex-based treatment disparities in interventional cardiology patients. Accordingly, each of the SCAI Clinical Interest Councils (coronary, peripheral, structural, and congenital heart disease [CHD]) participated in the development of this whitepaper addressing disparities in diagnosis, treatment, and outcomes in underserved populations. The councils were charged with summarizing the available data on prevalence, treatment, and outcomes and elucidating potential reasons for any disparities. Given the huge changes in racial and ethnic composition by age in the United States (Figure 1), it was difficult to determine disparities in rates of diagnosis and we expected to find some racial differences in prevalence of disease. For example, since the average age of patients undergoing transcatheter aortic valve replacement (TAVR) is 80 years, one may expect 80% of TAVR patients to be non-Hispanic White. Conversely, only 50% of congenital heart interventions would be expected to be performed in non-Hispanic Whites. Finally, we identified opportunities for SCAI to advance clinical care and equity for our patients, regardless of sex, ethnicity, or race.

Ethnic Difference of Thrombogenicity in Patients with Cardiovascular Disease: a Pandora Box to Explain Prognostic Differences

Arterial and venous atherothrombotic events are finely regulated processes involving a complex interplay between vulnerable blood, vulnerable vessel, and blood stasis. Vulnerable blood ('thrombogenicity') comprises complex interactions between cellular components and plasma factors (inflammatory, procoagulant, anticoagulant, and fibrinolytic factors). The extent of thrombogenicity may determine the progression of atheroma and the clinical manifestation of atherothrombotic events, with the highest thrombogenicity in African Americans and lowest in East Asians. Inherent thrombogenicity may influence clinical efficacy and safety of specific antithrombotic treatments in high-risk patients, which may in part explain the observation that East Asian patients have reduced anti-ischemic benefits and elevated bleeding risk with antithrombotic therapy compared to Caucasian patients. In this review, we discuss available evidence regarding the racial differences in thrombogenicity and its impact on clinical outcomes among patients with atherosclerotic cardiovascular disease.