Measurement of platelet reactivity of patients with cardiovascular disease on-treatment with acetyl salicylic acid: a prospective study

Clinical recurrence and antiplatelet drug resistance among patients with lower limb ischemia

There is a high prevalence rate of peripheral artery disease worldwide, with estimated cases exceeding 200 million. Most patients are under-diagnosed and under-treated, and there is a lack of knowledge regarding the best therapeutic regimen and therapy duration, which leads to many cases of recurrence, complications, and amputations. This study aims to explore clinical recurrence, which was defined as the worsening of chronic peripheral artery disease requiring hospital admission, and its relationship with antiplatelet drug resistance among patients with lower limb ischemia. This cohort study includes both retrospective and prospective recruitment of patients with chronic lower limb ischemia. Platelet aggregation tests were offered to the patients. Between February 2018 and November 2020, 147 patients were recruited from King Abdullah University Hospital and followed up for at least 1 year. Platelet aggregation tests were done for 93 patients who agreed to participate in this part of the study. The prevalence of chronic lower limb ischemia was higher in young male patients who are current smokers with co-morbid diseases such as hypertension, diabetes mellitus, and/or dyslipidemia. There was a significant association only of clinical recurrence with younger age (P = .011) and with low platelets count in severe stages of the disease (P = .047). No significant association was found in terms of laboratory resistance. The clinical recurrence rates of chronic lower limb ischemia were higher in younger patients and among those with low platelet counts in the severe stages of the disease. Despite the laboratory responsiveness to anti-platelet therapy, we observed significant clinical resistance and increased recurrence rates.

Clopidogrel-Related High Residual Platelet Reactivity Associated with Estimated Glomerular Filtration Rate in Patients with Acute Ischemic Stroke

INTRODUCTION

There are few studies on the relationship between the occurrence of clopidogrel-related high residual platelet reactivity (HRPR) and estimated glomerular filtration rate (eGFR) at admission in patients with ischemic stroke. The aim of this study was to investigate the possible relationship between the two.

METHODS

Patients who were hospitalized and diagnosed with acute ischemic stroke were recruited from July 1, 2017, to June 30, 2018, at Shanghai TCM-Integrated Hospital. Renal function was measured within 24 h of enrollment and eGFR was calculated. Patients were tested for platelet reactivity using the VerifyNow system after 7 days of antiplatelet therapy with clopidogrel 75 mg/d alone, and patients with P2Y12 reaction unit values ≥230 were diagnosed with HRPR. The association between HRPR and eGFR was analyzed.

RESULTS

A total of 274 patients were enrolled in the study, of whom 91 (33.21%) had HRPR. Multivariate logistic regression analysis suggested that an increased risk of HRPR was independently associated with female sex and reduced eGFR (female sex: OR = 2.24, 95% CI: 1.26-3.99, p = 0.006; mild chronic kidney disease [CKD]: OR = 2.95, 95% CI: 1.47-5.93, p = 0.002; moderate CKD: OR = 3.07, 95% CI: 1.08-8.75, p = 0.04).

CONCLUSION

Decreased eGFR is an independent risk factor for the occurrence of HRPR in patients with ischemic stroke.

Sex- and Gender-Based Pharmacological Response to Drugs

In humans, the combination of all sex-specific genetic, epigenetic, and hormonal influences of biologic sex produces different in vivo environments for male and female cells. We dissect how these influences of sex modify the pharmacokinetics and pharmacodynamics of multiple drugs and provide examples for common drugs acting on specific organ systems. We also discuss how gender of physicians and patients may influence the therapeutic response to drugs. We aim to highlight sex as a genetic modifier of the pharmacological response to drugs, which should be considered as a necessary step toward precision medicine that will benefit men and women. SIGNIFICANCE STATEMENT: This study discusses the influences of biologic sex on the pharmacokinetics and pharmacodynamics of drugs and provides examples for common drugs acting on specific organ systems. This study also discusses how gender of physicians and patients influence the therapeutic response to drugs.

Genotyping, Platelet Activation, and Cardiovascular Outcome in Patients after Percutaneous Coronary Intervention: Two Pieces of the Puzzle of Clopidogrel Resistance

OBJECTIVES

Individual platelet responses to antiplatelet therapy depend on genetic, cellular, and clinical factors. CYP2C19 and P2Y12 receptor polymorphisms are implicated in platelet responses to antiplatelet treatment. We aimed to evaluate the impact of CYP2C19 and C34T P2Y12 genotyping on platelet reactivity and cardiovascular outcome in patients after percutaneous coronary intervention (PCI) on clopidogrel treatment.

METHODS

We enrolled 408 patients with stable coronary artery disease (CAD) receiving aspirin and clopidogrel (75 mg/day) 1 month after PCI. High on-treatment platelet reactivity was evaluated using the VerifyNow Assay in a subset of patients. CYP2C19*2 and C34T P2Y12 genotyping was performed by real-time polymerase chain reaction. The primary end point was the composite of death or hospitalization for cardiovascular causes, and patients were followed for a median time of 13 months.

RESULTS

In the total study population, 37% were carriers of at least 1 CYP2C19*2 loss-of-function allele, and 53% were carriers of at least 1 C34T loss-of-function allele. Interestingly, homozygotes of the CYP2C19*2 loss-of-function allele had significantly increased P2Y12 reaction units (PRU) (p = 0.007). However, PRU did not differ between carriers and noncarriers of the C34T loss-of-function allele (p = 0.41). Moreover, carriers of CYP2C19*2 had an increased hazard ratio (HR) for the occurrence of the primary end point (for carriers HR = 1.96, 95% CI 1.05-3.66, p = 0.03), whereas the C34T polymorphism had no impact on the cardiovascular outcome (p = 0.17). Finally, PRU was associated with cardiovascular outcome even after adjustment for the presence of any reduced function allele polymorphism.

CONCLUSIONS

We documented a different effect of CYP2C19 and P2Y12 receptor polymorphisms on platelet reactivity and cardiovascular outcome in CAD patients after PCI on clopidogrel treatment. Importantly, increased platelet reactivity adversely affects the cardiovascular outcome independently of the studied polymorphisms.

Aspirin resistance may be identified by miR-92a in plasma combined with platelet distribution width

OBJECTIVE

Aspirin is a widely used drug for prevention of thrombotic events in cardiovascular patients, but approximately 25% of patients experience insufficient platelet inhibition due to aspirin, and remain in risk of cardiovascular events. This study aimed to investigate the value of circulating miR-92a and platelet size as biomarkers of the individual response to aspirin therapy.

METHODS

Blood samples were collected from 50 healthy blood donors without antithrombotic medication and 50 patients with intermittent claudication on daily aspirin therapy. Based on results from the arachidonic acid stimulated aggregation test on Multiplate®analyzer (ASPItest), patients were defined as aspirin resistant (n=10) or aspirin responders (n=40). Plasma levels of miR-92a were evaluated by RT-qPCR analysis and platelet distribution width (PDW) was used to assess platelet size variability. Receiver operating characteristic curves for miR-92a levels and PDW were used to set cut-off values for discrimination between aspirin responding and aspirin resistant patients.

RESULTS

When defining aspirin resistance as an ASPItest ≥30U, the optimal cut-off values for discrimination of aspirin responders and aspirin resistant patients were found to be PDW>11.8fL and a relative expression level of miR-92a>4.5. Using these cut-off values we could define a PDW/miR-92a-score with a specificity of 97.5% and a sensitivity of 80.0% in relation to detect aspirin resistance. The corresponding positive and negative predictive values were found to be 88.9% and 95.1%, respectively.

CONCLUSION

Aspirin resistance can potentially be identified by miR-92a levels in plasma combined with PDW.

Development of a concept for a personalized approach in the perioperative antiplatelet therapy administration/discontinuation management based on multiple electrode aggregometry in patients undergoing coronary artery surgery

In patients undergoing coronary artery surgery, improvements in clinical outcomes currently rely on continued refinements of the surgical technique and modulation of adjuvant pharmacotherapy. Despite medical and technological advances, negligible rate of bleeding and ischemic events still persist necessitating further improvements in patient management. Platelet function testing (PFT) might play an important role in meticulous balancing between the risk of bleeding and thrombotic events. A suitable balance can be achieved by implementing a personalized, PFT based approach in antiplatelet therapy (APT) administration/discontinuation management. Despite emerging evidence on the widespread variability in platelet inhibitory response to APT, numerous PFT devices and heterogeneity in reporting study results hamper pooling of the evidence which in turn results with a lack of consensus in "on treatment" platelet reactivity associated with ischemic and bleeding events in perioperative phase. The literature on multiple electrode aggregometry (Multiplate(®); Roche Diagnostics, Mannheim, Germany) in coronary artery disease patients was reviewed systematically. Based on the evidence evaluating the relationship between "drug specific" PFT and bleeding or adverse ischemic events, we sought to define therapeutic window for the most commonly administered antiplatelet drugs such as aspirin (ASPI test) and adenosine-diphosphate receptor blockers (ADP test). Preoperatively, APT administration was primarily focused to avoid bleeding complications. ASPI test value of 20 AUC and ADP test value of <73 AUC were set as cut-off values that delineate bleeding tendency. Postoperatively, "therapeutic window" was set to avoid both bleeding and adverse ischemic events. Therapeutic ranges were as follows: 20 AUC < ASPItest ≤ 30 AUC and 19AUC < ADP ≤ 46AUC, respectively. This is the first attempt to define PFT based "therapeutic window" according to, perioperative APT administration/discontinuation management would be targeted. It seems that the "one-size-fits-all" concept of perioperative APT administration management is outdated and further development of PFT based, personalized APT administration/discontinuation management is desirable. This concept therefore presents a possible step forward in patient care and provides a platform for further interventional trials whereby the impact of its application on clinical outcomes would be validated.

Pharmacogenomics of oral antiplatelet drugs

Pharmacogenomics has been implicated in the response variability of antiplatelet drugs in coronary artery disease (CAD), particularly for aspirin and clopidogrel. A large number of studies and several meta-analyses have been published on this topic, but until recently, there have been no clear conclusions and no definite guidelines on the clinical use of pharmacogenetic testing before prescribing antiplatelet drugs for CAD. In this review, the available evidence is summarized. The most consistent results are on clopidogrel, where CYP2C19 loss-of-function alleles are associated with stent thrombosis events. We recommend to genotype for CYP2C19 loss-of-function alleles in patients with CAD who are to undergo percutaneous coronary intervention and stenting, and to adjust the antiplatelet treatment based on the genotyping results.

Impact of dual antiplatelet therapy on outcomes among aspirin-resistant patients following coronary artery bypass grafting

Coronary artery bypass grafting is pivotal in the contemporary management of complex coronary artery disease. Interpatient variability to antiplatelet agents, however, harbors the potential to compromise the revascularization benefit by increasing the incidence of adverse events. This study was designed to define the impact of dual antiplatelet therapy (dAPT) on clinical outcomes among aspirin-resistant patients who underwent coronary artery surgery. We randomly assigned 219 aspirin-resistant patients according to multiple electrode aggregometry to receive clopidogrel (75 mg) plus aspirin (300 mg) or aspirin-monotherapy (300 mg). The primary end point was a composite outcome of all-cause death, nonfatal myocardial infarction, stroke, or cardiovascular hospitalization assessed at 6 months postoperatively. The primary end point occurred in 6% of patients assigned to dAPT and 10% of patients randomized to aspirin-monotherapy (relative risk 0.61, 95% confidence interval 0.25 to 1.51, p = 0.33). No significant treatment effect was noted in the occurrence of the safety end point. The total incidence of bleeding events was 25% and 19% in the dAPT and aspirin-monotherapy groups, respectively (relative risk 1.34, 95% confidence interval 0.80 to 2.23, p = 0.33). In the subgroup analysis, dAPT led to lower rates of adverse events in patients with a body mass index >30 kg/m(2) (0% vs 18%, p <0.01) and those <65 years (0% vs 10%, p = 0.02). In conclusion, the addition of clopidogrel in patients found to be aspirin resistant after coronary artery bypass grafting did not reduce the incidence of adverse events, nor did it increase the number of recorded bleeding events. dAPT did, however, lower the incidence of the primary end point in obese patients and those <65 years.

Prevalence of high on-treatment platelet reactivity in diabetic patients treated with aspirin

BACKGROUND

Randomized controlled trials have shown that ≤ 100 mg aspirin daily is not effective for primary prevention of cardiovascular events in diabetes; however, clinical and pharmacologic evidence suggests these patients need >100 mg for adequate antiplatelet activity. Although high on-treatment platelet reactivity (HTPR) could explain the lack of benefit, prevalence of HTPR in diabetes is not known. This systematic review examined the relationship between daily aspirin dose and prevalence of HTPR in patients with diabetes.

METHODS

Three electronic databases were searched until May 2013 using database-appropriate terms for aspirin, resistance, and diabetes. Studies were included if prevalence of HTPR was reported according to daily dose and diabetes status. Patients were stratified by daily aspirin dose and the weighted mean prevalence across studies was calculated. Where appropriate, pooled relative risks (RR) were calculated using a random-effects model.

RESULTS

Data were available from 31 studies that enrolled 2147 diabetic patients. Overall, prevalence of HTPR was 21.9% (95% confidence interval [CI], 15.2%-28.5%) in diabetic patients and 15.8% (95% CI, 11.4%-20.3%) in nondiabetic patients (pooled RR 1.36; 95% CI, 1.08-1.71; I(2) 56%). Prevalence appeared to be dose related, with 398 (23.6%) of 1689 diabetic patients using ≤ 100 mg daily having HTPR compared with 64 (12.3%) of 518 diabetic patients using 101-325 mg daily (pooled RR 1.70; 95% CI, 1.07-2.72; I(2) 0%).

CONCLUSIONS

Although these observations should be verified in a clinical trial, the possibility that 1 in 4 patients have HTPR with doses commonly used in diabetes could have significant implications on overall effectiveness of aspirin.