A brief review on high on-aspirin residual platelet reactivity

Aspirin 15cH has Different Effects on Morphology and Function of Lipopolysaccharide-Challenged RAW 264.7 Macrophages In Vitro Compared to a Pharmacological Dose of Aspirin

INTRODUCTION

 Aspirin is one of the most commonly used drugs worldwide. It is known to present antipyretic, anti-inflammatory and anti-thrombotic actions, making it extremely useful in a wide range of clinical contexts. Interestingly, homeopathically prepared Aspirin 15cH has been found to have a pro-thrombotic effect in rats, raising the hypothesis that Aspirin 15cH could also modulate the activity of inflammatory cells in different pathological processes.

OBJECTIVE

 Our objective was to assess what effect Aspirin 15cH has on RAW 264.7 macrophages in vitro.

METHODS

 The effects of Aspirin 15cH on biochemical and morphological activities of lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages were evaluated. These effects were compared with unchallenged macrophages (negative control), untreated LPS-stimulated macrophages, macrophages treated with succussed water (vehicle control), or aspirin 200 µg/mL (pharmacological inhibitor of LPS activity). Cell morphology (adhered cell area and cytoskeleton arrangements), cell viability, toll-like receptor-4 (TLR-4) expression, and the production of nitric oxide, cytokines and intracellular reactive oxygen species were assessed.

RESULTS

 Aspirin 15cH reduced the number of cells expressing TLR-4 on the surface (p = 0.03) and induced a "columnar" morphology of macrophage pseudopods, indicating changes in cytoskeleton arrangement. When cells were treated with both Aspirin 15cH and LPS, cell morphology became heterogeneous, suggesting that sub-populations of cells had differing sensitivities to LPS or Aspirin 15cH. Exposure of the cells to LPS alone, succussed water or aspirin 200 µg/mL produced effects consistent with the literature.

CONCLUSION

 Aspirin 15cH, aspirin 200 µg/mL, LPS and succussed water appear to act as independent stimuli able to induce different patterns of macrophage response. Aspirin 15cH induced changes suggestive of M2 polarization of the macrophages (i.e., toward a wound healing or tissue repair, rather than inflammatory, phenotype). These preliminary findings need to be confirmed in further specific studies.

Towards a greater understanding of reduced response to aspirin in children with congenital heart disease post-cardiac surgery using immature platelet fraction

OBJECTIVE

A high platelet turnover rate may produce a population of platelets that confers an inadequate response to aspirin. We aimed to investigate the relationship between residual platelet aggregation and platelet turnover in paediatric cardiology patients on aspirin monotherapy by evaluating the fraction of immature platelets as a marker for turnover and secondly to test the predictive value of the immature platelet fraction (IPF) to classify patients as responsive or non-responsive to aspirin.

METHODS

Sixty patients divided into two age categories (≤90 days, >90 days of age) were included in this prospective observational study. Patients were then stratified into tertiles using their IPF level. Platelet studies included thromboelastography with platelet mapping (TEGPM).

RESULTS

The overall incidence of 'inadequate response to aspirin' was 38 % in our patient cohort recently post-cardiac surgery a consequence that warrants further study. The frequency of inadequate response to aspirin was higher in the upper tertile of IPF when compared to the lower tertile, (88 %) versus (4 %) respectively (p < 0.05). The 'cut off' for IPF was determined to be 3.9 % with a sensitivity of 95.7 %, and a specificity of 92.9 % (area under the curve of 0.955 [CI 0.896-1.014, p < 0.05]).

CONCLUSION

This study demonstrates that inadequate response to aspirin occurs in approximately 38 % of patients undergoing specific high-risk congenital cardiac procedures using the dosing practice of a national centre. This study supports the hypothesis that an elevated platelet turnover may result in aspirin being less effective in patients who are recently post cardiac surgery. These data are of direct translational relevance.

Panax quinquefolius saponins combined with dual antiplatelet therapy enhanced platelet inhibition with alleviated gastric injury via regulating eicosanoids metabolism

BACKGROUND

Panax quinquefolius saponin (PQS) was shown beneficial against platelet adhesion and for gastroprotection. This study aimed to investigate the integrated efficacy of PQS with dual antiplatelet therapy (DAPT) on platelet aggregation, myocardial infarction (MI) expansion and gastric injury in a rat model of acute MI (AMI) and to explore the mechanism regarding arachidonic acid (AA)-derived eicosanoids metabolism.

METHODS

Wistar rats were subjected to left coronary artery occlusion to induce AMI model followed by treatment with DAPT, PQS or the combined therapy. Platelet aggregation was measured by light transmission aggregometry. Infarct size, myocardial histopathology was evaluated by TTC and H&E staining, respectively. Gastric mucosal injury was examined by scanning electron microscope (SEM). A comprehensive eicosanoids profile in plasma and gastric mucosa was characterized by liquid chromatography-mass spectrometer-based lipidomic analysis.

RESULTS

PQS+DAPT further decreased platelet aggregation, lessened infarction and attenuated cardiac injury compared with DAPT. Plasma lipidomic analysis revealed significantly increased synthesis of epoxyeicosatrienoic acid (EET) and prostaglandin (PG) I2 (potent inhibitors for platelet adhesion and aggregation) while markedly decreased thromboxane (TX) A2 (an agonist for platelet activation and thrombosis) by PQS+DAPT, relative to DAPT. DAPT induced overt gastric mucosal damage, which was attenuated by PQS co-administration. Mucosal gastroprotective PGs (PGE2, PGD2 and PGI2) were consistently increased after supplementation of PQS+DAPT.

CONCLUSIONS

Collectively, PQS+DAPT showed synergistic effect in platelet inhibition with ameliorated MI expansion partially through upregulation of AA/EET and AA/PGI2 synthesis while suppression of AA/TXA2 metabolism. PQS attenuated DAPT-induced gastric injury, which was mechanistically linked to increased mucosal PG production.

Monitoring antiplatelet therapy: where are we now?

Single antiplatelet therapy represents the cornerstone of thrombosis prevention in atherosclerotic cardiovascular disease. Dual antiplatelet therapy (DAPT), consisting of aspirin plus a P2Y12 inhibitor, is the standard of care for patients with acute coronary syndrome or undergoing both coronary and peripheral percutaneous interventions. Recent data suggest the efficacy of DAPT also after minor stroke. In this setting, a large body of evidence has documented that genetic and acquired patients' characteristics may affect the magnitude of platelet inhibition induced by antiplatelet agents. The implementation of tools allowing the identification and prediction of platelet inhibition has recently been shown to improve outcomes, leading to an optimal balance between antithrombotic efficacy and bleeding risk. We are therefore clearly moving towards tailored antiplatelet therapy. The aim of this paper is to summarize the available evidence on the evaluation of platelet inhibition in patients with coronary, peripheral, or cerebrovascular atherosclerosis. We will here focus on antiplatelet therapy based on both aspirin and P2Y12 inhibitors. In addition, we provide practical insights into the clinical settings in which it appears reasonable to implement antiplatelet therapy monitoring.

Viscoelastic Hemostatic Assays for Postpartum Hemorrhage

This article discusses the importance and effectiveness of viscoelastic hemostatic assays (VHAs) in assessing hemostatic competence and guiding blood component therapy (BCT) in patients with postpartum hemorrhage (PPH). In recent years, VHAs such as thromboelastography and rotational thromboelastometry have increasingly been used to guide BCT, hemostatic adjunctive therapy and prohemostatic agents in PPH. The three pillars of identifying hemostatic competence include clinical observation, common coagulation tests, and VHAs. VHAs are advantageous because they assess the cumulative contribution of all components of the blood throughout the entire formation of a clot, have fast turnaround times, and are point-of-care tests that can be followed serially. Despite these advantages, VHAs are underused due to poor understanding of correct technique and result interpretation, a paucity of widespread standardization, and a lack of large clinical trials. These VHAs can also be used in cases of uterine atony, preeclampsia, acute fatty liver of pregnancy, amniotic fluid embolism, placental abruption, genital tract trauma, surgical trauma, and inherited and prepartum acquired coagulopathies. There exists an immediate need for a point-of-care test that can equip obstetricians with rapid results on developing coagulopathic states. The use of VHAs in predicting and treating PPH, although in an incipient state, can fulfill this need.

Association between renal function and platelet reactivity during aspirin therapy in elderly patients with atherosclerotic cardiovascular disease

Background

Aspirin is the key treatment in the secondary prevention of atherosclerotic cardiovascular disease. High on-treatment platelet reactivity (HTPR) to aspirin has been reported to partially account for the enhanced risk of thrombotic events. In particular, HTPR has been described more frequently among elderly patients. The aim of this study was to identify the clinical and biological factors associated with HTPR in a real-life elderly population.

Methods

In this retrospective study, elderly patients with atherosclerotic cardiovascular disease on regular aspirin treatment were enrolled. Cardiovascular risk factors, routine biological parameters, comorbidities, and concomitant medications were recorded. The upper quartile of the platelet aggregation rate, determined by light transmission aggregometry with arachidonic acid, was defined as the HTPR group.

Results

A total of 304 patients were included (mean age 77 ± 8 years, 76% men). Patients in the HTPR group were older than the patients in the non-HTPR group (mean age: 79 ± 7 vs. 76 ± 8 years, p = 0.008). Patients with moderately decreased estimated glomerular filtration rate (eGFR) had a higher frequency of HTPR than patients with slightly decreased eGFR or normal eGFR (35.8, 22.5, 12.2%, respectively, p < 0.05). In multivariate analysis, an independent risk factor for HTPR was the eGFR (OR: 0.984, 95% CI: 0.980–0.988, p < 0.001).

Conclusions

Advanced age and decreased eGFR are correlated with poor pharmacodynamic response to aspirin.

Platelet activation and placenta-mediated adverse pregnancy outcomes: an ancillary study to the Effects of Aspirin in Gestation and Reproduction trial

BACKGROUND

Platelet activation may play a role in the pathophysiology of placenta-mediated obstetrical complications, as evidenced by the efficacy of aspirin in preventing preeclampsia, but published data regarding the relationship between biomarkers for platelet activation and adverse obstetrical outcomes are sparse. In particular, it is unknown whether prepregnancy biomarkers of platelet activation are associated with adverse pregnancy outcomes.

OBJECTIVE

This study aimed to determine the following: (1) whether maternal plasma concentrations of platelet factor 4 are associated with risk of placenta-mediated adverse obstetrical outcomes, and (2) whether these associations are modified by low-dose aspirin.

STUDY DESIGN

This ancillary study included measurement of platelet factor 4 among 1185 of 1228 women of reproductive age enrolled in the Effects of Aspirin in Gestation and Reproduction trial with available plasma samples, with relevant outcomes assessed among 584 women with pregnancies lasting at least 20 weeks' gestation. We measured platelet factor 4 in plasma samples obtained at the prepregnancy study visit (before randomization to low-dose aspirin or placebo), 12 weeks' gestation, and 28 weeks' gestation. The primary outcome was a composite of hypertensive disorders of pregnancy, placental abruption, and small-for-gestational-age infant. We estimated the relative risks (RRs) and 95% confidence intervals (CIs) for the association between platelet factor 4 and the composite and individual outcomes at each time point using log-binomial regression that was weighted to account for potential selection bias and adjusted for age, body mass index, education, income, and smoking. To evaluate the potential effect modification of aspirin, we stratified the analyses by aspirin treatment assignment.

RESULTS

During follow-up, 95 women experienced the composite adverse obstetrical outcome, with 57 cases of hypertensive disorders of pregnancy, 35 of small for gestational age, and 6 of placental abruption. Overall, prepregnancy platelet factor 4 was positively associated with the composite outcome (third tertile vs first tertile; relative risk, 2.36; 95% confidence interval, 1.38-4.03) and with hypertensive disorders of pregnancy (third tertile vs first tertile; relative risk, 2.14; 95% confidence interval, 1.08-4.23). In analyses stratified by treatment group, associations were stronger in the placebo group (third tertile vs first tertile; relative risk, 3.36; 95% confidence interval, 1.42-7.93) than in the aspirin group (third tertile vs first tertile; relative risk, 1.78; 95% confidence interval, 0.90-3.50).

CONCLUSION

High concentrations of platelet factor 4 before pregnancy are associated with increased risk of placenta-mediated adverse pregnancy outcomes, particularly for hypertensive disorders of pregnancy. Aspirin may mitigate the increased risk of these outcomes among women with higher plasma concentrations of preconception platelet factor 4, but low-dose aspirin nonresponders may require higher doses of aspirin or alternate therapies to achieve obstetrical risk reduction.

The effects of ginsenosides on platelet aggregation and vascular intima in the treatment of cardiovascular diseases: From molecular mechanisms to clinical applications

Thrombosis initiated by abnormal platelet aggregation is a pivotal pathological event that precedes most cases of cardiovascular diseases (CVD). Recently, growing evidence indicates that platelet could be a potential target for CVD prevention. However, as the conventional antithrombotic management strategy, applications of current antiplatelet agents are somewhat limited by their various side effects, such as bleeding risk and drug resistance. Hence, efforts have been made to search for agents as complementary therapies. Ginsenoside, the principal active component extracted from Panax ginseng, has gained much attention for its regulations on multiple crucial events of platelet aggregation. From structural characteristics to clinical applications, this review anatomized the intrinsic structure-function relationship of antiplatelet potency of ginsenosides, and the involved signal pathways were specifically summarized. Additionally, the emphasis was placed on clinical studies that investigate the antithrombotic efficacy of ginsenosides in the treatment of CVD. Further, a broad overview of approaches for improving the bioavailability of ginsenosides was concluded. Limitations and prospects of current studies were also discussed. This study may provide some new insights into the systematic understanding of ginsenosides in CVD treatment and lay a foundation for future research.

Factors Influencing Aspirin Hyporesponsiveness in Elderly Chinese Patients

Background

Aspirin hyporesponsiveness increases the risk of ischemic events. Therefore, it is important to investigate the factors influencing aspirin hyporesponsiveness.

Material/Methods

Patients aged 60 years or older who did not take aspirin before enrollment were included, with aspirin 100 mg/day administered after enrollment. The arachidonic acid-induced platelet aggregation rate (Ara) was measured by light transmission assay to evaluate aspirin responsiveness. Patients with Ara in the upper quartile after taking aspirin were assigned to the aspirin hyporesponsive group (Ara-Q4).

Results

A total of 292 elderly patients were included. The median value of Ara after taking aspirin was 5.87% (interquartile range 3.86–10.04%). Compared with the aspirin non-hyporesponsive group (Ara-Q1-3, Ara ≤10.04%, n=220), the level of uric acid (UA) (341.30 μmol/L vs. 299.10 μmol/L, p=0.027) and the ratios of β-blockers (9.72% vs. 2.27%, p=0.015) and diuretics (6.94% vs. 1.36%, p=0.036) were higher in the aspirin hyporesponsive group (Ara-Q4, Ara >10.04%, n=72). After multivariate adjustment, the results demonstrated baseline Ara (odds ratio [OR]: 1.030, 95% confidence interval [CI]: 1.004–1.056, p=0.021), UA level (OR: 1.003, 95% CI: 1.000–1.006, p=0.038), and β-blockers use (OR: 5.487, 95% CI: 1.515–19.870, p=0.010) were independently and positively associated with aspirin hyporesponsiveness.

Conclusions

This study found that baseline Ara, UA level, and β-blockers use were independently and positively associated with aspirin hyporesponsiveness in elderly Chinese patients, which needs to be validated in large-scale studies.

Early natural history of neotissue formation in tissue-engineered vascular grafts in a murine model

Aim: To characterize early events in neotissue formation during the first 2 weeks after vascular scaffold implantation. Materials & methods: Biodegradable polymeric scaffolds were implanted as abdominal inferior vena cava interposition grafts in wild-type mice. Results: All scaffolds explanted at day 1 contained a platelet-rich mural thrombus. Within the first few days, the majority of cell infiltration appeared to be from myeloid cells at the peritoneal surface with modest infiltration along the lumen. Host reaction to the graft was distinct between the scaffold and mural thrombus; the scaffold stimulated an escalating foreign body reaction, whereas the thrombus was quickly remodeled into collagen-rich neotissue. Conclusion: Mural thrombi remodel into neotissue that persistently occludes the lumen of vascular grafts.

Arachidonic acid causes lysis of blood cells and ADP-dependent platelet activation responses in platelet function tests

The use of arachidonic acid (AA) to stimulate platelets is considered as a specific approach to study aspirin treatment efficacy. However, very high concentrations of AA are used, and it has been previously reported that AA can induce cell lysis in other settings. Several clinical studies have reported decreased responses to AA in whole blood tests in the presence of clopidogrel. Our aim was to investigate whether unspecific effects contribute to AA-induced aggregation and platelet activation in light transmission aggregometry (LTA) in platelet-rich plasma (PRP), and in assays using whole blood, multiple electrode aggregometry (MEA, Multiplate®), and flow cytometry. We report that cell lysis, especially of red blood cells, does occur at concentrations of AA used in the clinical tests and that ADP is very important for the AA-induced platelet activation responses. In flow cytometry, very limited platelet activation was detected before reaching AA concentrations in the millimolar range, where cell lysis also occurred, making it problematic to develop a reliable flow cytometry assay using AA as reagent. We conclude that cell lysis and ADP release contribute to AA-induced platelet responses, most markedly in whole blood assays. This finding could potentially explain some differences between studies comparing methods using whole blood and PRP and also how clopidogrel treatment could influence AA-induced aggregation results in previously published studies. Our findings highlight some issues with AA as reagent for platelet activation, which also have an impact on how platelet activation assays using AA should be interpreted.

Investigation into the causes of aspirin resistance in healthy dogs

Antiplatelet effects of acetylsalicylic acid (ASA, aspirin) may be poor in some individuals. Additionally, no method exists for predicting poor ASA response (resistance) in individual dogs. This study's main objective was to determine whether poor ASA response results from pharmacodynamic or pharmacokinetic causes. ASA concentrations causing 50% inhibition of platelet aggregation (in vitro IC50) were determined using whole blood collected from 21 drug-free healthy dogs to evaluate intrinsic sensitivity of platelets to ASA. Dogs were then administered ASA at 4 mg/kg once orally. Percent decrease in platelet aggregation from baseline, and plasma ASA and salicylic acid (SA) concentrations (expressed as AUC values) were measured for up to 3 hr. By 3 hr, 13/21 (62%) dogs showed >50% aggregation inhibition, while 8/21 (38%) dogs showed <50% inhibition. Aggregation inhibition values were negatively correlated with in vitro IC50 values (Rs = -0.49; p = 0.028) and positively correlated with ASA concentrations (Rs = 0.48; p = 0.03). Furthermore, ASA concentrations were strongly negatively correlated (Rs = -0.88; p < 0.001) with SA/ASA concentration ratios, an index of ASA metabolism to SA by esterase enzymes. Multiple linear regression analysis indicated that 59% (p < 0.001) of interindividual variability in aggregation inhibition was explained by in vitro IC50 values (29% of variability) and ASA concentrations (29% of variability). Consequently, poor in vivo ASA response in these dogs resulted from both pharmacodynamic (decreased platelet sensitivity) and pharmacokinetic (lower ASA concentrations) causes. Lower ASA concentrations may be explained by reduced bioavailability associated with higher esterase activities.

The impact of CYP2C19*2, CYP4F2*3, and clinical factors on platelet aggregation, CYP4F2 enzyme activity, and 20-hydroxyeicosatetraenoic acid concentration in patients treated with dual antiplatelet therapy

: The aim of the current study was to evaluate the impact of CYP2C192 (rs4244285), CYP4F23 (rs2108622), and nongenetic factors on platelet aggregation and to investigate the mechanism of CYP4F2's effect on platelet aggregation in the patients treated with dual antiplatelet therapy. A total of 146 patients were included in this study. Ticagrelor or clopidogrel were administered in a loading dose of 180 mg and 600 mg, respectively, in combination with aspirin (300 mg). Blood samples for analysis were taken the next morning after antiplatelet therapy induction. Clopidogrel users with the CYP2C1912 variant had higher platelet aggregation values (median 43, range 30-54%) compared with 11 wild-type carriers (median 33, range 15-77%; P = 0.009). Carriers of the CYP4F213 variant had higher platelet aggregation values than carriers of the 33 variant (median 34, range 8-70% vs. median 24.5, range 10-47%, P = 0.016, respectively). Higher CYP4F2 concentrations were detected in clopidogrel users than in ticagrelor users (median 3.6, range 1.6-22.0 ng/ml vs. median 2.3, range 1.6-27.2 ng/ml, P = 0.056, respectively) and in carriers of the CYP4F213 variant compared with carriers of the 11 variant (median 4.3, range 1.6-27.2 ng/ml vs. median 2.4, range 1.6-22.0 ng/ml, P = 0.009, respectively). No correlation between plasma 20-hydroxyeicosatetraenoic acid and CYP4F2 enzyme concentrations were detected (r = -0.045, P = 0.587). Our results proved that CYP2C192 might significantly affect antiplatelet function of clopidogrel. Plasma CYP4F2 concentrations were significantly lower in ticagrelor users than in clopidogrel users.

vWF/ADAMTS13 is associated with on-aspirin residual platelet reactivity and clinical outcome in patients with stable coronary artery disease

Background

The mechanisms behind residual platelet reactivity (RPR) despite aspirin treatment are not established. It has been shown that coronary artery disease (CAD) patients with high on-aspirin RPR have elevated levels of von Willebrand factor (vWF). ADAMTS13 is a metalloprotease cleaving ultra large vWF multimers into less active fragments.

Our aim was to investigate whether ADAMTS13 and vWF/ADAMTS13 ratio were associated with high RPR, and further with clinical endpoints after 2 years.

Methods

Stable aspirin-treated CAD patients (n = 999) from the ASCET trial. RPR was assessed by PFA-100. ADAMTS13 antigen and activity were analysed using chromogenic assays. Endpoints were a composite of acute myocardial infarction, stroke and death.

Results

The number of patients with high RPR was 258 (25.8%). Their serum thromboxane B₂ (TxB₂) levels were low, indicating inhibition of COX-1. They had significantly lower levels of ADAMTS13 antigen compared to patients with low RPR (517 vs 544 ng/mL, p = 0.001) and significantly lower ADAMTS13 activity (0.99 vs 1.04 IU/mL, p = 0.020). The differences were more pronounced when relating RPR to ratios of vWF/ADAMTS13 antigen and vWF/ADAMTS13 activity (p < 0.001, both). We found an inverse correlation between vWF and ADAMTS13 antigen (r = −0.14, p < 0.001) and ADAMTS13 activity (r = −0.11, p < 0.001). No correlations between TxB₂ and ADAMTS13 antigen or activity, were observed, implying that ADAMTS13 is not involved in TxB2 production. Patients who experienced endpoints (n = 73) had higher vWF level (113 vs 105%, p = 0.032) and vWF/ADAMTS13 antigen ratio (0.23 vs 0.20, p = 0.012) compared to patients without. When dichotomizing vWF/ADAMTS13 antigen at median level we observed that patients above median had higher risk for suffering endpoints, with an adjusted OR of 1.86 (95% CI 1.45, 2.82).

Conclusion

These results indicate that ADAMTS13 is of importance for RPR, and that it in combination with vWF also is associated with clinical endpoints in stable CAD patients on aspirin.

Trial registration

Clinicaltrials.gov NCT00222261. Registered 13.09.2005. Retrospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s12959-017-0151-3) contains supplementary material, which is available to authorized users.

A randomised controlled trial comparing a dietary antiplatelet, the water-soluble tomato extract Fruitflow, with 75 mg aspirin in healthy subjects

BACKGROUND/OBJECTIVES

Increasing numbers of food ingredients are gaining acknowledgement, via regulated health claims, of benefits to human health. One such is a water-soluble tomato extract, Fruitflow (FF), a dietary antiplatelet. We examined relative platelet responses to FF and to 75 mg aspirin (ASA) in healthy subjects.

SUBJECTS/METHODS

A total of 47 healthy subjects completed a double-blinded randomised controlled trial following a crossover design. Acute and 7-day treatments with 75 mg ASA were compared with control with and without concomitant FF, over a 5-h timecourse. Platelet aggregation response agonist, platelet thromboxane A2 release, plasma clotting times and time to form a primary haemostatic clot (PFA-100 closure time, TTC) were measured.

RESULTS

Administration of all treatments lowered platelet function and thromboxane A2 generation, and extended the TTC, relative to baseline (P<0.001) and to control (P<0.001). Plasma clotting times were not affected. A single 75 mg dose of ASA showed approximately equal efficacy to a dose of FF, whereas daily 75 mg ASA was approximately three times as effective after 7 days (P=0.002). Platelet responses were heterogenous with distinct weak and strong responder groups. Weak ASA responders retained a functional platelet response to collagen agonist and were responsive to FF. Concomitant FF and ASA did not lead to significant additive effects.

CONCLUSIONS

The suppression of platelet function observed after consuming FF is approximately one-third that of daily 75 mg ASA. The reversible action of FF renders it less likely to overextend the time to form a primary haemostatic clot than ASA, an important safety consideration for primary prevention.

Validation of aspirin response-related transcripts in patients with coronary artery disease and preliminary investigation on CMTM5 function

Aspirin is widely used in the prevention of cardiovascular diseases, but the antiplatelet responses vary from one patient to another. To validate aspirin response related transcripts and illustrate their roles in predicting cardiovascular events, we have quantified the relative expression of 14 transcripts previously identified as related to high on-aspirin platelet reactivity (HAPR) in 223 patients with coronary artery disease (CAD) on regular aspirin treatment. All patients were followed up regularly for cardiovascular events (CVE). The mean age of our enrolled population was 75.80±8.57years. HAPR patients showed no significant differences in terms of co-morbidities and combined drugs. Besides, the relative expression of HLA-DQA1 was significantly lower in low on-aspirin platelet reactivity (LAPR) patients, when compared with HAPR and high normal (HN) group (p=0.028). What's more, the number of arteries involved, HAPR status and the relative expression of CLU, CMTM5 and SPARC were independent risk factors for CVE during follow up (p<0.05). In addition, overexpression of CMTM5 attenuated endothelial cells (ECs) migration and proliferation, with significantly decreased phosphorylated-Akt levels, while its inhibition promoted these processes in vitro (p<0.05).Our study provides evidence that circulating transcripts might be potential biomarkers in predicting cardiovascular events. CMTM5 might exert anti-atherosclerotic effects via suppressing migration and proliferation in the vessel wall. Nevertheless, larger-scale and long-term studies are still needed.

Effects of Aspirin on Endothelial Function and Hypertension

PURPOSE OF REVIEW

Endothelial dysfunction is intimately related to the development of various cardiovascular diseases, including hypertension, and is often used as a target for pharmacological treatment. The scope of this review is to assess effects of aspirin on endothelial function and their clinical implication in arterial hypertension.

RECENT FINDINGS

Emerging data indicate the role of platelets in the development of vascular inflammation due to the release of proinflammatory mediators, for example, triggered largely by thromboxane. Vascular inflammation further promotes oxidative stress, diminished synthesis of vasodilators, proaggregatory and procoagulant state. These changes translate into vasoconstriction, impaired circulation and thrombotic complications. Aspirin inhibits thromboxane synthesis, abolishes platelets activation and acetylates enzymes switching them to the synthesis of anti-inflammatory substances. Aspirin pleiotropic effects have not been fully elucidated yet. In secondary prevention studies, the decrease in cardiovascular events with aspirin outweighs bleeding risks, but this is not the case in primary prevention settings. Ongoing trials will provide more evidence on whether to expand the use of aspirin or stay within current recommendations.

Stent Thrombosis Patients with Hyporesponsiveness to Clopidogrel, Prasugrel, and Ticagrelor: A Case Series Using Short Thromboelastography

Patients after percutaneous coronary intervention (PCI) with stent implantation and functional hyporesponsiveness to P₂Y₁₂ inhibitors are at higher risk of ischaemic events, particularly stent thrombosis (ST). It is currently not routine practice to assess the functional response to these agents. However, concern over functional hyporesponsiveness to clopidogrel has led to widespread uptake of prasugrel and ticagrelor as the default P₂Y₁₂ inhibitor after stent implantation in patients with acute coronary syndrome. Here we report, for the first time, 3 cases in which patients who have had ST exhibit hyporesponsiveness to clopidogrel, prasugrel, and ticagrelor.

PPM1A Methylation Is Associated With Vascular Recurrence in Aspirin-Treated Patients

BACKGROUND AND PURPOSE

Despite great efforts by pharmacogenetic studies, the causes of aspirin failure to prevent the recurrence of ischemic events remain unclear. Our aim was to study whether epigenetics could be associated with the risk of vascular recurrence in aspirin-treated stroke patients.

METHODS

We performed an epigenetic joint analysis study in 327 patients treated with aspirin. In the discovery stage, we performed a nested case-control study in 38 matched ischemic stroke patients in whom 450 000 methylation sites were analyzed. Nineteen patients presented vascular recurrence after stroke, and 19 matched patients did not present vascular recurrence during the first year of follow-up. In a second stage, 289 new patients were analyzed by EpiTYPER.

RESULTS

The following 3 differentially methylated candidate CpG sites, were identified in the discovery stage and analyzed in the second stage: cg26039762 (P=9.69×10(-06), RAF1), cg04985020 (P=3.47×10(-03), PPM1A), and cg08419850 (P=3.47×10(-03), KCNQ1). Joint analysis identified an epigenome-wide association for cg04985020 (PPM1A; P=1.78×10(-07)), with vascular recurrence in patients treated with aspirin.

CONCLUSIONS

The pattern of differential methylation in PPM1A is associated with vascular recurrence in aspirin-treated stroke patients.

The lack of aspirin resistance in patients with coronary artery disease

Background

Aspirin resistance established by different laboratory methods is still a debated problem. Using COX1 specific methods no aspirin resistance was detected among healthy volunteers. Here we tested the effect of chronic aspirin treatment on platelets from patients with stable coronary artery disease. The expression of COX2 mRNA in platelets and its influences on the effect of aspirin was also investigated.

Methods

One hundred and forty four patients were enrolled in the study. The direct measurement of COX1 acetylation was carried out by monoclonal antibodies specific to acetylated and non-acetylated COX1 (acCOX1 and nacCOX1) using Western blotting technique. Arachidonic acid (AA) induced TXB₂ production by platelets was measured by competitive immunoassay. AA induced platelet aggregation, ATP secretion and VerifyNow Aspirin Assay were also performed. COX2 and COX1 mRNA expression in platelets were measured in 56 patients by RT-qPCR.

Results

In 138 patients only acCOX1 was detected, in the remaining six patients nacCOX1 disappeared after a compliance period. AA induced TXB₂ production by platelets was very low in all patients including the 6 patients after compliance. AA induced platelet aggregation, secretion and with a few exceptions the VerifyNow Assay also demonstrated the effect of aspirin. Smoking, diabetes mellitus and inflammatory conditions did not influence the results. The very low amount of COX2 mRNA detected in 39 % of the investigated platelets did not influence the effect of aspirin.

Conclusions

No aspirin resistance was detected among patients with stable coronary artery disease. COX2 expression in platelets did not influence the effect of aspirin.