Vasodilator-stimulated Phosphoprotein Phosphorylation Assay Research Articles

High On-Treatment Platelet Reactivity in Patients Undergoing Complex Percutaneous Coronary Interventions.

Patient response to P2Y12 inhibitor therapy is heterogeneous, and those with high on-treatment platelet reactivity (HTPR) are at an increased risk of thrombotic complications. The aim of our study was to determine whether selecting a high-risk patient group of individuals after complex percutaneous coronary intervention (PCI) would show the clinical benefit of HTPR testing for preventing thrombotic complications. Blood samples of patients after complex PCI were acquired 1 day and 1 month after the intervention. The samples were tested using vasodilator-stimulated phosphoprotein phosphorylation (VASP-P) and platelet function assay (PFA). The occurrence of clinically significant stent thrombosis with repeated revascularization of the target vessel was observed over a 1-year period. One day after PCI, 37% of patients had HTPR as established by VASP-P. One month after PCI, the percentage of patients with HTPR decreased to 30.9%. According to PFA, 1 day after PCI, 33.3% of patients had HTPR. This percentage declined to 19.8% after 1 month. All measurements identified a significantly higher proportion of HTPR in patients on clopidogrel compared to ticagrelor and prasugrel. Two cases of early stent thrombosis and 1 case of late stent thrombosis were identified. Further study of adenosine diphosphate receptor blocker on-treatment response in patients undergoing complex PCI is necessary.

Advanced pharmacodynamics of cangrelor in healthy volunteers: a dose-finding, open-label, pilot trial

BackgroundHigh on-treatment platelet reactivity (HTPR) remains a major problem in the acute management of ST-elevation myocardial infarction (STEMI), leading to higher rates of stent thrombosis and mortality. We aimed to investigate a novel, prehospital treatment strategy using cangrelor and tested its pharmacodynamic effects in a model using healthy volunteers.MethodsWe conducted a dose-finding, open-label, pilot trial including 12 healthy volunteers and tested three ascending bolus infusions of cangrelor (5 mg, 10 mg and 20 mg) and a bolus infusion followed by a continuous infusion via an intravenous (IV) flow regulator. Platelet function was assessed using multiple electrode aggregometry (MEA), vasodilator-stimulated phosphoprotein phosphorylation assay (VASP-P) and the platelet function analyzer. In an ex vivo experiment, epinephrine was used to counteract the antiplatelet effect of cangrelor.ResultsAll cangrelor bolus infusions resulted in immediate and pronounced platelet inhibition. Bolus infusions of cangrelor 20 mg resulted in sufficient platelet inhibition assessed by MEA for 20 min in 90% of subjects. Infusion of cangrelor via the IV flow regulator resulted in sufficient platelet inhibition throughout the course of administration. Ex vivo epinephrine, in concentrations of 200 and 500 ng/mL was able to partially reverse the antiplatelet effect of cangrelor in a dose-dependent manner.ConclusionsWeight-adapted bolus infusions followed by a continuous infusion of cangrelor via IV flow regulator result in immediate and pronounced platelet inhibition in healthy subjects. Cangrelor given as weight-adapted bolus infusion followed by a continuous infusion using an IV flow regulator may be a viable treatment approach for effective and well controllable prehospital platelet inhibition.Trial registrationEC (Medical University of Vienna) 1835/2019 and EudraCT 2019-002792-34.

Bentracimab for Ticagrelor Reversal in Patients Undergoing Urgent Surgery

BackgroundTicagrelor is a reversible oral P2Y12 platelet inhibitor used to treat patients with acute coronary syndromes, prior myocardial infarction, high-risk coronary artery disease, transient ischemic attack, or ischemic stroke. A healthy volunteer study showed that the intravenous monoclonal antibody bentracimab rapidly reverses ticagrelor, but the effect in patients was unknown.MethodsIn a prespecified interim analysis of a single-arm, prospective study, bentracimab was evaluated in ticagrelor-treated patients who required urgent surgery or had major hemorrhage. The extent of reversal was determined using the VerifyNow P2Y12 assay. Clinical hemostasis was assessed by central adjudication using validated criteria. Treatment-emergent safety events were evaluated. The trial is ongoing and will enroll approximately 200 patients with evaluable data.ResultsOf 150 enrolled patients, 142 required urgent surgery and 8 had major hemorrhage. For the end-point analysis, 129 patients had analyzable platelet data; 122 had data on adjudicated hemostasis. Bentracimab provided a rapid reversal of ticagrelor’s antiplatelet effects within 5 to 10 minutes. The reversal was sustained for more than 24 hours, as measured with the VerifyNow P2Y12 and vasodilator-stimulated phosphoprotein phosphorylation assays (P<0.001, with both assays and in all subgroups). Adjudicated hemostasis was achieved for more than 90% of patients (P<0.001); approximately 5% of patients had thrombotic events. No allergic or infusion-related reactions were reported.ConclusionsBentracimab provided immediate and sustained reversal of the antiplatelet effects of ticagrelor in patients undergoing surgical procedures. (Funded by PhaseBio Pharmaceuticals, Inc.; ClinicalTrials.gov number, NCT04286438.)

Association of FMO3 rs1736557 polymorphism with clopidogrel response in Chinese patients with coronary artery disease

Dual antiplatelet therapy with aspirin and clopidogrel is commonly used for coronary artery disease (CAD) patients undergoing percutaneous coronary intervention to prevent stent thrombosis and ischemic events. However, some patients show high on-treatment platelet reactivity (HTPR) during clopidogrel therapy. Genetic factors such as loss-of-function variants of CYP2C19 are validated to increase the risk of HTPR. Flavin-containing monooxygenase 3 (FMO3) is reported to be associated with potency of platelet responsiveness and thrombosis. This study aimed to explore the association between FMO3 rs1736557 polymorphism and clopidogrel response. Five hundred twenty-two Chinese CAD patients treated with dual antiplatelet therapy were recruited from Xiangya Hospital. After oral administration of 300mg loading dose (LD) clopidogrel for 12-24h or 75mg daily maintenance dose (MD) clopidogrel for at least 5days, the platelet reaction index (PRI) was determined by vasodilator-stimulated phosphoprotein-phosphorylation assay. FMO3 rs1736557, CYP2C19*2, and CYP2C19*3 polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Mean PRI value was significantly higher in CYP2C19 poor metabolizers (PMs) and intermediate metabolizers (IMs) than the extensive metabolizers (EMs) (p < 0.001). In addition, FMO3 rs1736557 AA homozygotes showed significantly lower PRI as compared with carriers of the major rs1736557 G allele in the entire cohort and in the MD cohort (p = 0.011, p = 0.008, respectively). The risk of HTPR was decreased significantly in carriers of the rs1736557 A allele (AA vs GG: OR = 0.316, 95% CI: 0.137-0.726, p = 0.005; AA vs GA: OR = 0.249, 95% CI: 0.104-0.597, p = 0.001; AA vs GG+GA: OR = 0.294, 95% CI: 0.129-0.669, p = 0.002), and the association was observed mainly in patients carrying the CYP2C19 LOF allele and in those administered with MD. The FMO3 rs1736557 AA genotype was related to an increased the antiplatelet potency of clopidogrel in Chinese CAD patients. Additional studies are required to verify this finding.

The relation between ABO blood types and clinical and platelet function parameters in patients who underwent percutaneous coronary intervention.

ABO blood groups have been associated with venous thromboembolism and arterial thrombosis. Although platelets play key roles in thrombogenesis, the relation between ABO groups and platelets is not well known and was investigated in this study. ABO blood type information was retrospectively obtained for 206 patients who underwent percutaneous coronary intervention (PCI) and received dual antiplatelet therapy with aspirin and clopidogrel. Platelet function was measured using VerifyNow system, light transmission aggregometry, thromboxane B2, urinary 11-dehydrothromboxane B2, and vasodilator-stimulated phosphoprotein phosphorylation assays. Samples were also tested following treatment with 10 and 30 µmol/l of aspirin or 30 and 100 µmol/l of P2Y12 inhibitor 2-methylthioadenosine 5'-monophosphate triethylammonium salt hydrate (2-MeSAMP). Forty-four clinical and 30 platelet function parameters were analyzed. Patients were categorized as aspirin or clopidogrel poor responder (PR) according to cutoff levels of each test. Blood type A was significantly associated with myocardial infarction (MI) history [odds ratio (OR)=2.50, 95% confidence interval (CI)=1.37-4.58, P=0.003], higher baseline troponin T and creatine kinase-MB (CK-MB) index, post-PCI CK-MB index, and platelet reactivity index (PRI), and being PR against 2-MeSAMP (OR=5.75, 95% CI=1.51-21.90, P=0.010). Blood type O was associated with higher arachidonic acid-induced platelet aggregation and negatively associated with MI history (OR=0.47, 95% CI=0.26-0.84, P=0.010), PRI and being PR against clopidogrel (OR=0.54, 95% CI=0.30-0.99, P=0.043) and 2-MeSAMP (OR=0.16, 95% CI=0.03-0.76, P=0.021). Blood type A was found as a risk factor for MI. Higher arachidonic acid-induced aggregation in group O and higher PRI in group A against aspirin and P2Y12 inhibitor treatment, respectively, may suggest alternative antiplatelet therapies for PRs with these blood types.

Platelet function testing: dead or alive

Background High on-treatment platelet reactivity (HTPR) to antiplatelet medication leads to ischemic events, whereas low on-treatment platelet reactivity (LTPR) increases bleeding risk. However, various trials have failed to demonstrate superiority of tailored antiplatelet regimens (ARCTIC, ANTARCTIC, Trigger-PCI, and GRAVITAS). TROPICAL-ACS was the first study that demonstrated the benefit of tailoring antiplatelet medication according to platelet function analysis. A potential reason may be that different platelet function assays were used in these trials. Objectives To evaluate whether the results of platelet function tests are comparable. Patients/Methods We tested three commonly used assays - light transmission aggregometry (LTA), (Multiplate impedance aggregometry [MP]), and vasodilator-stimulated phosphoprotein phosphorylation assay (VASP) - in 23 patients receiving dual antiplatelet therapy with aspirin and clopidogrel. Results With LTA, HTPR occurred in 57% of patients; with VASP, it occurred in 43% of patients; and with MP, it occurred in 13% of patients. According to LTA, only 35% of patients were in the therapeutic window; according to VASP, 57% of patients were in the therapeutic window; and according to MP, 48% of patients were in the therapeutic window. With LTA, LTPR occurred in 9% of patients; with VASP, it occurred in 0% of patients; and with MP, it occurred in 39% of patients. Therefore, the prevalences of HTPR and LTPR differed significantly between assays. Remarkably, in 17% of patients, one assay showed HTPR whereas another showed LTPR. Conclusions The results of different platelet function assays differ substantially. Up to now, only TROPICAL-ACS had demonstrated a benefit of tailoring antiplatelet medication according to platelet function analysis. Future trials are needed to evaluate whether the platelet function assay used in TROPICAL-ACS is the 'correct' one and revives platelet function testing.

Comparison of four methods to assess high-on platelet reactivity under P2Y12 receptor inhibitor

P2Y12 receptor inhibitors are antiplatelet agents commonly prescribed in the treatment of coronary artery disease. Their efficacy can be limited by high on-treatment platelet reactivity (HPR), which can be evaluated by different biological assays. Most commonly, HPR is evaluated by flow cytometric vasodilator-stimulated phosphoprotein-phosphorylation (VASP-P) assay, which can be time consuming. To evaluate the potential interest of novel technologies, we compared four different assays.Ninety patients receiving P2Y12 inhibitors were included. Four technologies were evaluated: the current standard test measuring VASP-P by flow cytometry, the historical reference test based on light transmittance aggregation (LTA), and two relatively novel techniques: whole blood multiple electrode aggregometry (MEA) and platelet function analyzer (PFA), which are less time consuming.The three latter tests were compared with the VASP-P assay as a reference using receiver operating characteristics (ROC) analysis: LTA has an excellent comparability with the VASP test (ROC AUC > 0.9); the other two tests (multiplate and PFA) have only satisfactory comparability (ROC AUC around 0.7) and therefore may not replace the VASP “gold standard” test, if importance is attached to a quantitative assessment of the substitution parameter of VASP. Nevertheless, if a binary approach of the anti-aggregation result is sought, then one can conclude that the three tests are equivalent since Cohen’s kappa coefficients are very close for the three tests (k = 0.548 for LTA; k = 0.554 for MEA; k = 0.570 for PFA/P2Y), and a similar proportion of patients are misclassified (15% for LTA, 14% for MEA, and 13.6% for PFA). Discriminant factor analysis using all the parameters provided by each test did not improve the diagnostic performance of MEA or PFA.In conclusion, only LTA shows a good comparability to the VASP assay using ROC curve analysis, probably because misclassified patients have results close to the cutoff values. All three tests have moderate agreement regarding the classification of patients as responders to P2Y12 inhibition.

Switching from clopidogrel to prasugrel to protect early invasive treatment in acute coronary syndromes: Results of the switch over trial

BackgroundClopidogrel is used to pretreat patients with non-ST elevation acute coronary syndromes (NSTE-ACS), but prasugrel provides better platelet inhibition with improved outcome. However, switching from clopidogrel at the time of percutaneous coronary intervention (PCI) remains incompletely defined. Our aim was to compare the pharmacodynamic (PD) effects of 3 prasugrel loading doses (LDs; G1:10mg, G2: 30mg, and G3: 60mg) before PCI. A fourth group, continuing clopidogrel, served as control (G4). Methods100 clopidogrel-pretreated patients were enrolled and blood collected before PCI, 30min, 1, 2, 4, 6, 24 and 48h thereafter. Platelet inhibition was measured by vasodilator-stimulated phosphoprotein phosphorylation (VASP) and Verify-Now assays. The end-points (EP) was the difference of PD effect at 4h between G3 and G4 (primary EP) with hierarchic evaluation between G2 and G1 versus G4 (secondary EP). A mixed-design ANOVA statistic was used to compare the four group scores over time. ResultsBaseline characteristics were balanced across the groups. Only patients receiving 60 and 30mg prasugrel LDs showed a rapid (<1h) and significant (p<0.001) platelet inhibition up to 48h after PCI·The primary EP was met by G3 (p<0.0001), but also G2 scored different (p<0–001) from G4 at 4h after PCI. Similar findings were observed with Verify-Now. No differences in 30-day clinical outcomes were observed across groups. ConclusionsSwitching NSTE-ACS patients before PCI to prasugrel 60 or 30mg LDs determined a better and faster platelet inhibition than continuing clopidogrel, while PCI it is still underway.

Cigarette smoking reduces platelet reactivity independently of clopidogrel treatment in patients with non-ST elevation acute coronary syndromes

Smokers receiving clopidogrel show a lower residual platelet reactivity than non-smokers, a phenomenon generally ascribed to smoking-induced increased production of clopidogrel active metabolite, but also associated with the high hemoglobin levels of smokers, which decreases platelet reactivity in tests that measure platelet function in whole blood. We evaluated the impact of cigarette smoking and of hemoglobin levels on platelet reactivity index (PRI) measured by the vasodilator-stimulated phosphoprotein phosphorylation (VASP-P) assay in whole blood samples from patients with non-ST elevation acute coronary syndrome (NSTE-ACS) undergoing percutaneous coronary interventions, both before and after clopidogrel administration.PRI was measured in 718 clopidogrel-naïve NSTE-ACS patients, both before and 1 month after treatment with clopidogrel (75 mg daily). Smokers (n = 347, 48%) had significantly lower mean PRI levels at both baseline (57.7 ± 24.1 vs. 64.8 ± 19.8, p < 0.001) and 1 month (43.4 ± 20.3% vs. 46.8 ± 18.0%, p = 0.017) than non-smokers. After adjusting for potential confounders (age, sex, diabetes, chronic kidney disease, Syntax score>15), the β coefficient of smoke on PRI was −8.51 [−11.90 to −5.11, p < 0.001] at baseline and −3.41 [−6.30 to −0.51, p = 0.02] after 1 month. Hemoglobin was higher in smokers (13.8 ± 1.5 g/dL) than non-smokers (13.1 ± 1.7 g/dL, p < 0.001), but was not significantly correlated with PRI both at baseline (Rho = 0.02, p = 0.60) and at 1 month (Rho = 0.01, p = 0.80).Our analysis confirms that clopidogrel-treated smokers have lower platelet reactivity, measured by the VASP-P assay, compared to clopidogrel-treated non-smokers. However, smokers had lower platelet reactivity already before receiving clopidogrel treatment, suggesting that smoke affects platelet reactivity independently of its potential effect on the pharmacokinetics of clopidogrel. Our data also indicate that such an effect is not mediated by increased hemoglobin levels.

Prasugrel in critically ill patients

SummaryWhile prasugrel is indicated for the treatment of myocardial infarction, its effects in the most severely affected patients requiring intensive care is unknown, so that we measured the antiplatelet effects and sparse pharmacokinetics of prasugrel in critically ill patients. Twenty-three patients admitted to medical intensive care units, who were treated with 10 mg prasugrel once daily, were included in this prospective trial. Critically ill patients responded poorly to daily prasugrel treatment: adenosine diphosphate (ADP)-induced aggregation in whole blood classified 65 % (95 % confidence intervals (CI) 43–84 %) of patients as having high on treatment platelet reactivity, platelet function under high shear rates even 74 % (95 %CI 52–90 %). There was only limited additional inhibition provided 2 hours after the next dose of prasugrel. In contrast, insufficient inhibition of the target was only seen in 26 % (95 %CI 10–48 %) of patients as measured by the vasodilator-stimulated phosphoprotein phosphorylation (VASP-P) assay. Low effective plasma levels of prasugrel active metabolite were measured at trough [0.5 (quartiles 0.5–1.1) ng/ml at baseline], and 2 hours after intake [5.7 (3.8–9.8) ng/ml], but showed coefficients of variation of ~70 %. In sum, inhibition of platelet aggregation by prasugrel is not uniform but highly variable in critically ill patients, similar to clopidogrel in a general population. The pharmacokinetic measurements indicate that poor absorption/metabolism of prasugrel may partly contribute while inflammation induced heightened intrinsic platelet reactivity may also play a role. Supplementary Material to this article is available online at www.thrombosis-online.com . Note: This work was performed at the Medical University of Vienna, Austria.

Platelet turnover predicts outcome after coronary intervention.

SummaryElevated platelet turnover contributes to high platelet reactivity. High platelet reactivity after percutaneous coronary intervention (PCI) is associated with major adverse cardiovascular events (MACE). The purpose of this study was to determine the prognostic value of platelet turnover and function with regard to MACE after PCI with stent implantation. In this prospective observational study, 486 consecutive patients after PCI on aspirin and clopidogrel were included to determine platelet turnover (mean platelet volume (MPV), reticulated platelet fraction (RPF)) and platelet function (multiple electrode aggregometry (MEA), vasodilator-stimulated phosphoprotein-phosphorylation (VASP-P) assay). At six-months follow-up, MACE occurred in 10.7 % of patients. RPF (odds ratio [OR]=1.173 (95% confidence interval [CI 95 %] 1.040–1.324), p=0.009) and MPV (OR=1.459 (CI 95 % 1.059–2.008), p=0.021) were univariable predictors of MACE, whereas VASP-P (OR=1.016 (CI 95 % 1.000–1.032), p=0.052) and MEA (OR=0.999 (CI 95 % 0.980–1.017), p=0.895) failed to predict MACE. RPF remained the only platelet variable independently associated with MACE. The best model to predict MACE included: troponin I (OR=1.007 (CI 95 % 1.002–1.012), p=0.009), RPF (OR=1.136 (CI 95 % 1.001–1.288), p=0.048), CRP (OR=1.008 (CI 95 % 1.001–1.014), p=0.023) and history of myocardial infarction (OR=2.039 (CI 95 % 1.093–3.806), p=0.025). RPF (OR=1.211 (CI 95 % 1.042–1.406), p=0.012) was also independently associated with in-hospital bleedings. In conclusion, RPF as index of platelet turnover is an independent predictor of MACE and bleeding events in PCI patients on dual antiplatelet therapy. Since RPF can reliably be quantified along with routine haemograms, RPF might easily be applied in the setting of cardiovascular risk prediction.

Platelet Inhibition With Ticagrelor 60 mg Versus 90 mg Twice Daily in the PEGASUS-TIMI 54 Trial

BackgroundThe PEGASUS-TIMI 54 (Prevention of Cardiovascular Events in Patients with Prior Heart Attack Using Ticagrelor Compared to Placebo on a Background of Aspirin–Thrombolysis In Myocardial Infarction 54) trial studied 2 doses of ticagrelor, 90 mg twice a day (bid) and 60 mg bid, for long-term prevention of ischemic events in patients with prior myocardial infarction. Both doses similarly reduced the rate of ischemic events versus placebo. The pharmacokinetics and pharmacodynamics of ticagrelor 60 mg bid have not been studied. ObjectivesIn this study, the authors sought to study the pharmacokinetics and pharmacodynamics for ticagrelor 60 mg compared with 90 mg bid. MethodsA total of 180 patients who received >4 weeks of study medication had blood sampling in the morning pre-maintenance dose and again 2 h post-dose. All patients received aspirin. Plasma levels of ticagrelor and its active metabolite AR-C124910XX were determined. P2Y12 inhibition was assessed by the VerifyNow P2Y12 assay (Accumetrics, Inc., San Diego, California) (P2Y12 reaction units [PRU]), light transmittance aggregometry (adenosine diphosphate 5 and 20 μmol/l and arachidonic acid), and vasodilator-stimulated phosphoprotein phosphorylation assays. VerifyNow Aspirin assays and serum thromboxane B2 measurements were performed. ResultsMean pre- and post-dose plasma levels of ticagrelor were 35% and 38% lower, respectively, with 60 mg versus 90 mg. Both doses achieved high levels of platelet inhibition pre- and post-dose, with numerically slightly more variability with 60 mg: mean (SD) pre-dose PRU values were 59 ± 63 and 47 ± 43 for ticagrelor 60 and 90 mg, respectively (p = 0.34). High platelet reactivity, determined as PRU >208, was rare with the 60-mg pre-dose and was absent post-dose. Platelet reactivity pre- and post-dose, as measured by light transmittance aggregometry or vasodilator-stimulated phosphoprotein assays, was numerically but not significantly lower with 90 mg than with 60 mg. Aspirin response was not affected by either dose. ConclusionsTicagrelor 60 mg bid achieved high levels of peak and trough platelet inhibition in nearly all patients, similar to that with 90 mg bid, helping to explain the efficacy of the lower ticagrelor dose in PEGASUS-TIMI 54.

Influence of platelet reactivity on BARC classification in East Asian patients undergoing percutaneous coronary intervention. Results of the ACCEL-BLEED study.

An increasing body of data suggests that East Asian patients have differing risk profiles for both thrombophilia and bleeding compared with Western population. This study was designed to evaluate the relationship of bleeding to platelet function in East Asians undergoing percutaneous coronary intervention (PCI). Patients who had undergone uneventful PCI (n= 301) were prospectively enrolled and bleeding events were evaluated during dual antiplatelet therapy (DAPT) with aspirin and clopidogrel. Platelet function was measured during hospitalisation and at 30-day follow-up by light transmittance aggregometry (LTA) and vasodilator-stimulated phosphoprotein phosphorylation (VASP-P) assay. During 30-day follow-up, 29.2 % of patients (n= 88) experienced post-discharge Bleeding Academic Research Consortium (BARC) complications (24.6 % and 7.0 % of BARC type 1 and 2, respectively). Patients presenting with acute myocardial infarction had fewer episodes of type 1 BARC bleeding (odds ratio: 0.41; 95 % confidence interval: 0.22 to 0.76; p= 0.005). The cut-off of low platelet reactivity (LPR) (20 µM ADP-induced platelet aggregation ≤ 46.1 %; platelet reactivity index ≤ 45.1 %) was the independent determinant of type 2 BARC bleeding (odds ratio: 3.55 and 4.44; p= 0.009 and 0.002, respectively). The first 30-day BARC bleeding episodes were associated with an increased rate of subsequent premature DAPT discontinuation during one-year follow-up (4.7 % vs 11.4 %; odds ratio: 2.60; 95 % confidence interval: 1.04 to 6.50; p= 0.035). In conclusion, among East Asians, mild bleeding episodes are common early after PCI and are associated with premature DAPT discontinuation. Type 2 BARC bleeding episodes are associated with LPR cut-offs measured at 30 days post-discharge.

Angiotensin-Converting Enzyme Inhibitors' Influence on Antiplatelet Therapy of Clopidogrel in ACS.

Clopidogrel is a prodrug, the minority of which is converted to an active metabolite by hepatic cytochrome P450 (CYP2C19), however, most of it is metabolized to inactive substance by hepatic carboxylesterase1 (CES1). Meanwhile angiotensin-converting enzyme inhibitors (ACEIs) are mostly metabolized by CES1. We aimed to assess the impact of ACEIs on platelet inhibition by clopidogrel. We genotyped variants CES1, CYP2C19*2 and *3 in 502 patients with acute coronary syndrome (ACS) receiving clopidogrel therapy, and analyzed the effects of ACEIs on responsiveness to clopidogrel by the vasodilator-stimulated phosphoprotein (VASP) phosphorylation assay and ADP-stimulated impedance whole blood platelet aggregation assay. It showed that the allele frequency of CES1 c.428A was 0% in these patients. 45.22% (227/502) of these patients were carriers of CYP2C19*2 or CYP2C9*3 loss-of-function alleles. Among them, 57.71% (131/227) of the patients with CYP2C19 variants received ACEIs therapy. In a total of 502 patients, there was no difference in the VASP-PRI or the impedance whole blood platelet aggregation assay between the ACEIs group and non-ACEIs group [56.26 ± 14.55% versus 57.76 ± 13.56%, p = 0.241; 0 (0 - 2) Ω vs. 0 (0 - 2) Ω, p = 0.856]. In the CYP2C19 variant patients, there was no difference in the VASP-PRI or the impedance whole blood platelet aggregation assay between ACEIs group and non-ACEIs group [57.24 ± 15.12% versus 58.07 ± 13.90%, p = 0.667; 0 (0 - 2) Ω versus 0 (0 - 2) Ω, p = 0.536]. In the subgroups of ACS patients (unstable angina, non-ST-segment elevation myocardial infarction, ST-segment elevation myocardial infarction), there was no difference in the VASP-PRI between the ACEIs group and non-ACEIs group [55.81 ± 15.24% versus 58.37 ± 13.31%, p = 0.103; 55.76 ± 15.20% versus 49.09 ± 15.22%, p = 0.098; 58.13 ± 11.48% versus 61.87 ± 10.34%, p = 0.221], and there was no difference in the impedance whole blood platelet aggregation assay between ACEIs group and non-ACEIs group [0 (0 - 2) Ω versus 0 (0 - 2) Ω, p = 0.936; 0 (0 - 2) Ω versus 0 (0 - 2) Ω, p = 0.625; 0 (0 - 1.25) Ω versus 0 (0 - 1.5) Ω, p = 0.788]. In our study, when ACEIs were used with clopidogrel, platelet response to clopidogrel was not affected. These findings suggest that the drug interaction between clopidogrel and ACEI is of little relevance in platelet function.

Association of MicroRNAs and YRNAs With Platelet Function.

Platelets shed microRNAs (miRNAs). Plasma miRNAs change on platelet inhibition. It is unclear whether plasma miRNA levels correlate with platelet function. To link small RNAs to platelet reactivity. Next-generation sequencing of small RNAs in plasma revealed 2 peaks at 22 to 23 and 32 to 33 nucleotides corresponding to miRNAs and YRNAs, respectively. Among YRNAs, predominantly, fragments of RNY4 and RNY5 were detected. Plasma miRNAs and YRNAs were measured in 125 patients with a history of acute coronary syndrome who had undergone detailed assessment of platelet function 30 days after the acute event. Using quantitative real-time polymerase chain reactions, 92 miRNAs were assessed in patients with acute coronary syndrome on different antiplatelet therapies. Key platelet-related miRNAs and YRNAs were correlated with platelet function tests. MiR-223 (rp=0.28; n=121; P=0.002), miR-126 (rp=0.22; n=121; P=0.016), and other abundant platelet miRNAs and YRNAs showed significant positive correlations with the vasodilator-stimulated phosphoprotein phosphorylation assay. YRNAs, miR-126, and miR-223 were also among the small RNAs showing the greatest dependency on platelets and strongly correlated with plasma levels of P-selectin, platelet factor 4, and platelet basic protein in the population-based Bruneck study (n=669). A single-nucleotide polymorphism that facilitates processing of pri-miR-126 to mature miR-126 accounted for a rise in circulating platelet activation markers. Inhibition of miR-126 in mice reduced platelet aggregation. MiR-126 directly and indirectly affects ADAM9 and P2Y12 receptor expression. Levels of platelet-related plasma miRNAs and YRNAs correlate with platelet function tests in patients with acute coronary syndrome and platelet activation markers in the general population. Alterations in miR-126 affect platelet reactivity.

Morphine decreases ticagrelor concentrations but not its antiplatelet effects: a randomized trial in healthy volunteers.

Our recent drug interaction trial with clopidogrel shows that morphine decreases the concentrations and pharmacodynamic effects of clopidogrel, which could lead to treatment failure in susceptible individuals. We hypothesized that the pharmacodynamic consequences of drug-drug interactions would be less between morphine and ticagrelor. Twenty-four healthy subjects received a loading dose of 180 mg ticagrelor together with placebo or 5 mg morphine intravenously in a randomized, double-blind, placebo-controlled, crossover trial. Pharmacokinetics were determined by liquid chromatography tandem mass spectrometry, and ticagrelor pharmacodynamic effects were measured by platelet function tests (whole blood platelet aggregation: multiplate, platelet plug formation: PFA-100, vasodilator-stimulated phosphoprotein (VASP) phosphorylation assay). Concomitant i.v. injection of morphine slows drug resorption of ticagrelor and its active metabolite (P < 0·05) by 1 h and decreases plasma levels of ticagrelor and its active metabolite by 25-31% (P ≤ 0·03) and the drug exposure (area under the curve) by 22-23% (P ≤ 0·01). Importantly, however, the pharmacodynamic effects of ticagrelor on platelet aggregation in whole blood, platelet plug formation and VASP phosphorylation are not affected by morphine. Morphine co-administration moderately decreases ticagrelor plasma concentrations but does not inhibit its pharmacodynamic effects in healthy volunteers within 6 h after drug administration. Limitations of our trial include the investigation in healthy volunteers under standardized conditions, which does not necessarily reflect a realistic emergency scenario.

Abstract 19153: Morphine Delays and Attenuates Ticagrelor Exposure and Action in Patients With Myocardial Infarction: The Randomized, Double-blind, Placebo-controlled Impression Trial

Introduction: The currently available data from observational studies and a randomized trial on clopidogrel conducted in healthy volunteers suggest existence of drug-drug interactions between morphine and oral P2Y12 inhibitors, when administered together. Hypothesis: We aimed to test the hypothesis that morfine administered intravenously excerts the negative impact on pharmacokinetics and pharmacodynamics of ticagrelor and its active metabolite (AR-C124910XX) in patients with myocardial infarction. Methods: In a single center, randomized, double-blind trial, participants were assigned in a 1:1 ratio to receive intravenously either morphine (5 mg) or placebo, followed by a 180 mg loading dose of ticagrelor. Pharmacokinetics was determined with liquid chromatography tandem mass spectrometry, while ticagrelor antiplatelet effect was measured with up to 3 different platelet function tests: vasodilator-stimulated phosphoprotein (VASP) phosphorylation assay, multiple electrode aggregometry and VerifyNow P2Y12. Results: The pharmacokinetic and pharmacodynamic assessment was performed in 70 patients (35 in each study group). Morphine administration lowered the total exposure to ticagrelor and its active metabolite by 35.6% (AUC(0-12): 6307 vs. 9791 ng·h/mL; p=0.003) and 37.1% (AUC(0-12): 1503 vs. 2388 ng·h/mL; p=0.008), respectively, with a concomitant delay in maximal plasma concentration of ticagrelor (4 vs. 2 h; p=0.002) and AR-C124910XX (6 vs. 4 h; p=0.03) in morphine-treated patients. Multiple regression analysis showed that lower AUC(0-12) values for ticagrelor were associated with morphine administration (p=0.003) and the presence of ST-segment elevation myocardial infarction (p=0.010). All three methods of platelet reactivity assessment consistently showed a stronger antiplatelet effect of ticagrelor in the placebo group as reflected by a higher prevalence of high platelet reactivity in patients receiving morphine. Conclusions: Morphine delays and attenuates ticagrelor exposure and action in patients with myocardial infarction.

Effect of prasugrel in patients with asthma: results of PRINA, a randomized, double‐blind, placebo‐controlled, cross‐over study

Although experimental studies have demonstrated that platelets are proinflammatory cells, no randomized studies have tested the anti-inflammatory effect of antiplatelet agents in humans. The platelet P2Y12 receptors mediated bronchial inflammation in a mouse model of asthma, suggesting that P2Y12 represents a pharmacologic target for asthma. In this proof-of concept, placebo-controlled, randomized, cross-over study, we tested the effects of the P2Y12 antagonist prasugrel on bronchial hyperreactivity of asthmatic patients. Twenty-six asthmatic patients were randomly and blindly allocated to prasugrel (10 mg once daily) or placebo for 15 days. After a ≥ 15-day wash-out, patients were crossed over to the alternative treatment. Before and after each treatment, patients underwent a bronchial provocation test with mannitol and measurement of fractional exhaled nitric oxide (FeNO). Inhibition of P2Y12 -dependent platelet reactivity (platelet reactivity index [PRI]) was measured with the vasodilator-stimulated phosphoprotein phosphorylation assay. The provocative dose of mannitol causing a 15% drop in forced expiratory volume in 1 s increased from 142 mg (95% confidence interval [CI] 82-202) to 187 mg (95% CI 113-262) after prasugrel treatment (P = 0.09), and did not change after placebo treatment (136 mg [95% CI 76-196] and 144 mg [95% CI 84-204], P = 0.65). FeNO did not change after either treatment. The PRI decreased from 80% (95% CI 77-83) to 23% (95% CI 7-29) after prasugrel treatment (P < 0.001) and remained unchanged after placebo. Our proof-of-concept, randomized, controlled study is the first one to test in vivo the anti-inflammatory effects of platelet inhibition in human patients. The results suggest that pharmacologic inhibition of P2Y12 receptors may slightly reduce the bronchial inflammatory burden, and lay the groundwork for further studies, with clinical endpoints.

Abstract 20657: Plasma MicroRNAs Correlate With Platelet Reactivity in Patients With Acute Coronary Syndrome: Association With Platelet Function

Introduction: Platelets contribute plasma microRNAs (miRNAs). Levels of platelet-related miRNAs change in plasma in response to platelet inhibition. Hypothesis: It is currently unclear how plasma miRNAs correlate to platelet function in patients with acute coronary syndrome (ACS). Methods: We measured plasma miRNAs in 125 patients with a history of ACS (STEMI, NSTEMI or unstable angina) who have undergone detailed assessment of platelet function 30 days after the acute event. Results: Using custom-made quantitative real-time polymerase chain reaction plates, 92 miRNAs were assessed in patients on different anti-platelet therapies (clopidogrel, prasugrel, aspirin). Key platelet-related miRNAs were correlated with platelet function tests, including optical aggregometry using the agonists ADP and arachidonic acid, VerifyNow P2Y12 assay and vasodilator-stimulated phosphoprotein (VASP) phosphorylation assay. Significant associations were obtained for miR-126 with the VerifyNow (rp=0.347, n=39, P=0.033) and VASP assay (rp=0.224, n=125, P=0.013). Other abundant platelet miRNAs also showed strong correlations with the VASP assay: miR-223 (rp =0.231, P=0.003), miR-191 (rp =0.243, P=0.007), miR-24 (rp =0.246, P=0.006), miR-197 (rp=0.293, P=0.008), miR-30b (rp=0.230, P=0.010) and miR-20b (rp=0.231 , P=0.010). Conclusions: Levels of platelet-related plasma miRNAs correlate with platelet function tests in ACS patients. Our findings reinforce the concept that platelets are an important contributor to the plasma miRNA pool.

Effects of vorapaxar on platelet reactivity and biomarker expression in non-ST-elevation acute coronary syndromes

Vorapaxar is an antagonist of the protease activated receptor-1 (PAR-1), the principal platelet thrombin receptor. The Thrombin Receptor Antagonist for Clinical Event Reduction (TRACER) trial evaluated vorapaxar compared to placebo in non-ST-elevation (NSTE)-acute coronary syndrome (ACS) patients. It was the study's objective to assess the pharmacodynamic effects of vorapaxar versus placebo that included aspirin or a thienopyridine or, frequently, a combination of both agents in NSTE-ACS patients. In a substudy involving 249 patients, platelet aggregation was assessed by light transmittance aggregometry (LTA) in 85 subjects (41 placebo, 44 vorapaxar) using the agonists thrombin receptor activating peptide (TRAP, 15 μM), adenosine diphosphate (ADP, 20 μM), and the combination of collagen-related peptide (2.5 μg/ml) + ADP (5 μM) + TRAP (15 μM) (CAT). VerifyNow® IIb/IIIa and vasodilator-stimulated phosphoprotein (VASP) phosphorylation assays were performed, and platelet PAR-1 expression, plasma platelet/endothelial and inflammatory biomarkers were determined before and during treatment. LTA responses to TRAP and CAT and VerifyNow results were markedly inhibited by vorapaxar. Maximal LTA response to TRAP (median, interquartile range) 2 hours post loading dose: placebo 68% (53-75%) and vorapaxar 3% (2-6%), p<0.0001. ADP inhibition was greater in the vorapaxar group at 4 hours and one month (p<0.01). In contrast to the placebo group, PAR-1 receptor number in the vorapaxar group at one month was significantly lower than the baseline (179 vs 225; p=0.004). There were significant changes in selected biomarker levels between the two treatment groups. In conclusion, vorapaxar caused a potent inhibition of PAR-1-mediated platelet aggregation. Further studies are needed to explore vorapaxar effect on P2Y12 inhibition, PAR-1 expression and biomarkers and its contribution to clinical outcomes.