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

2014 ◽  
Vol 111 (05) ◽  
pp. 883-891 ◽  
Author(s):  
Susan S. Smyth ◽  
David J. Moliterno ◽  
Tyrus L. Rorick ◽  
Tiziano Moccetti ◽  
Marco Valgimigli ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Reactivity ◽  
Adenosine Diphosphate ◽  
Light Transmittance ◽  
Clinical Event ◽  
Thrombin Receptor ◽  
Coronary Syndrome ◽  
Vasp Phosphorylation ◽  
Potent Inhibition ◽  
St Elevation

SummaryVorapaxar 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.

Whole blood platelet aggregation kinetics under cardiopulmonary bypass: A pilot study

2019 ◽  
Vol 43 (3) ◽  
pp. 208-214
Author(s):  
Tobias Petzold ◽  
Erik Bagaev ◽  
Helen Herzog ◽  
Frank Born ◽  
Dominik Hoechter ◽  
...  
Keyword(s):  
Cardiopulmonary Bypass ◽  
Platelet Aggregation ◽  
Life Support ◽  
Platelet Reactivity ◽  
Extracorporeal Life Support ◽  
Adenosine Diphosphate ◽  
Thrombin Receptor ◽  
Electrode Impedance ◽  
Platelet Counts ◽  
Impedance Aggregometry

Assessing the platelets’ functional status during surgery on cardiopulmonary bypass is challenging. This study used multiple electrode impedance aggregometry (Multiplate®) to create a timeline of platelet aggregation changes as induced by cardiopulmonary bypass in antiplatelet-naive patients undergoing elective surgery for mitral valve regurgitation. We performed six consecutive measurements (T1: pre-operatively, T2: after heparinization, T3: 3 min after establishment of cardiopulmonary bypass, T4: immediately after administration of cardioplegia, T5: 5 min after administration of cardioplegia, and T6: 45 min after administration of cardioplegia). Platelet aggregation was determined after stimulation with 3.2-μg/mL collagen, 6.4-μM adenosine diphosphate, and 32-μM thrombin receptor activating peptide. Five patients were included (age: 64 ± 10 years, one female). We observed a decrease in hematocrit levels by −17.1% ± 3.7% (T1 vs T6) with a drop after establishment of cardiopulmonary bypass (T2 vs T3) and slightly decreasing platelet counts by −6.2% ± 7.7% (T1 vs T6). Immediately after establishment of cardiopulmonary bypass (T2 vs T3), we observed reduced platelet aggregation responses for stimulation with adenosine diphosphate (−19.7% ± 12.8%) and thrombin receptor activating peptide (−19.3% ± 6.3%). Interestingly, we found augmented platelet aggregation for all stimuli 45 min after administration of cardioplegia (T5 vs T6) with the strongest increase for collagen (+83.4% ± 42.8%; adenosine diphosphate: +39.0% ± 37.2%; thrombin receptor activating peptide: +34.5% ± 18.5%). Thus, after an initial drop due to hemodilution upon establishment of cardiopulmonary bypass, platelet reactivity increased over time which was not outweighed by decreasing platelet counts due to mechanical platelet destruction and absorption. These findings have implications for rational transfusion, peri-operative antiplatelet therapy, and for the management of patients on other extracorporeal support, such as extracorporeal life support or extracorporeal membrane oxygenation.

Cross validation of the Multiple Electrode Aggregometry

2009 ◽  
Vol 102 (08) ◽  
pp. 397-403 ◽  
Author(s):  
Jolanta Siller-Matula ◽  
Ghazaleh Gouya ◽  
Michael Wolzt ◽  
Bernd Jilma
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Cross Validation ◽  
Platelet Reactivity ◽  
Adenosine Diphosphate ◽  
Multiple Electrode Aggregometry ◽  
Vasp Phosphorylation ◽  
Function Analyzer ◽  
Platelet Function Analyzer ◽  
Multiple Electrode

SummarySeveral test systems exist for assessment of platelet function in patients under clopidogrel or aspirin therapy. The objective was to cross-validate the Multiple Electrode Aggregometry (MEA) with three other methods used for determining platelet reactivity under treatment with clopidogrel and aspirin. Platelet function was assessed by the MEA, Vasodilator Stimulated Phosphoprotein (VASP) phosphorylation assay, Platelet Function Analyzer-100 (PFA-100) and the Cone and Platelet Analyzer. Measurements were performed in blood from nine healthy volunteers at baseline, 2, 4, 6 and 72 hours after clopidogrel and aspirin loading. The apparent effect size for clopidogrel and aspirin was greatest for the MEA: treatment induced a 19-fold difference in the arachidonic acid-induced platelet aggregation and an 11-fold difference in the adenosine diphosphate-induced platelet aggregation before/after treatment. For comparison, aspirin and clopidogrel induced only 2.0– to 2.6 -fold changes in other tests (VASP assay, Cone and Platelet Analyzer and PFA-100). Maximal effects were seen 2 hours after aspirin loading and shorter than 72 hours after clopidogrel loading. In conclusion, aspirin and clopidogrel produce stronger signals in the MEA compared to several other methods.

ADP-induced platelet aggregation and platelet reactivity index VASP are good predictive markers for clinical outcomes in non-ST elevation acute coronary syndrome

2007 ◽  
Vol 98 (10) ◽  
pp. 838-843 ◽  
Author(s):  
Corinne Frere ◽  
Thomas Cuisset ◽  
Jacques Quilici ◽  
Laurence Camoin ◽  
Joseph Carvajal ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Reactivity ◽  
Roc Curves ◽  
Coronary Intervention ◽  
Reactivity Index ◽  
Predictive Values ◽  
Coronary Syndrome ◽  
Increased Risk ◽  
St Elevation ◽  
Ischemic Events

SummaryClopidogrel responsiveness has been proposed to be involved in recurrent ischemic events after stenting for non-ST elevation acute coronary syndromes (NSTE ACS). However, its biological definition is not consensual. We assess the value ofADP-induced platelet aggregation (ADP-Ag) and platelet reactivity indexVASP (PRI VASP) in predicting recurrent ischemic events in patients with NSTE ACS undergoing percutaneous coronary intervention (PCI). We studied 195 consecutive NSTE ACS patients undergoing PCI after a 600 mg loading dose of clopidogrel. ADPAg and PRI VASP were analysed. The primary end-point was recurrent ischemic events within 30 days of PCI. It occurred in 14 patients (7%). Construction of ROC curves to examine the value of predictive models showed that sensitivity and specificity for primary endpoint were 79% and 76%, respectively, for a maximal intensity of ADP-Ag ≥70%, 93% and 50% for PRIVASP> 53%. The positive and negative predictive values were 21% and 98%, respectively, for ADP-Ag ≥70%, 12% and 99% for PRIVASP> 53%. In patients with NSTE ACS undergoing PCI, ADP-Ag and PRI VASP identify low responders to clopidogrel with an increased risk of recurrent ischemic events with respective cut-off values of 70% and 53%.

CYP2C19*2 and *3 Polymorphisms Are Associated with High Post- Treatment Platelet Reactivity in Korean Patients with Acute Coronary Syndrome Undergoing Percutanous Coronary Intervention.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 982-982
Author(s):  
In-Suk Kim ◽  
Young-Hoon Jeong ◽  
Gyeong-Won Lee
Keyword(s):  
Acute Coronary Syndrome ◽  
Platelet Aggregation ◽  
Platelet Reactivity ◽  
Coronary Intervention ◽  
Post Treatment ◽  
Light Transmittance ◽  
Platelet Response ◽  
Korean Patients ◽  
Coronary Syndrome ◽  
Percutanous Coronary Intervention

Abstract Background: Cytochrome P450 (CYP) 2C19 is an enzyme showing genetic polymorphism that may cause marked interindividual and interethnic variation in the metabolism and disposition of its substrates. CYP2C19*2 and CYP2C19*3 are the most common of CYP2C19 polymorphisms, and show phenotypic poor metabolism. Recent data have shown that the CYP2C19*2 loss-of-function allele is associated with a marked decrease in platelet response to clopidogrel in healthy controls and Caucasian patients with acute coronary syndrome. However, It is unknown whether CYP2C19 *3, which is frequently noted in Asian, is also associated with platelet response to clopidogrel. Therefore, this study was conducted to analyze the effect of CYP2C19 *2 and *3 polymorphisms on high post-treatment platelet reactivity (HPPR) on clopidogrel in Korean patients with acute coronary syndrome, as a representative of Asian populations. Methods: The study included 136 consecutive patients undergoing percutanous coronary intervention (PCI). Adenosine diphosphate (ADP)-induced platelet aggregation by light transmittance aggregometry (LTA) and the VerifyNow P2Y12 assay (Ultegra rapid platelet function assay; Accumetrics Inc., USA) were assessed after a loading dose and after the maintenance dose of clopidogrel before discharge. CYP2C19 genotype was analyzed by Snapshot method. Results: The genotypic distributions of CYP2C19*1/*1, *1/*2, *1/*3, *2/*2, and *2/*3 were 57 (41.9%), 47 (34.6%), 12 (8.8%), 14 (10.3%), 6 (4.4%), and 6(4.4%), respectively. The frequencies of CYP2C19 mutant alleles in Korean were higher than Caucasians. The CYP2C19*2 and CYP2C19*3 polymorphisms were significantly associated with persistent higher platelet aggregation by LTA, and lower inhibition of platelet reactivity by VerifyNow P2Y12 assay after clopidogrel than CYP2C19*1 genotype. The CYP2C19*2 and *3 alleles were more frequent in clopidogrel hyporesponsiveness, defined by persistent HPPR (5 uM ADP-induced platelet aggregation >50%; p = 0.01). Conclusions: This study suggests that the CYPC19*2 and *3 alleles influence clopidogrel hyporesponsiveness after clopidogrel in Asian patients with acute coronary syndromes undergoing PCI. These findings can have a significant impact on the future design of pharmacognetic antiaggregant strategies for acute coronary syndrome on antiplatelet treatment.

scholarly journals ANTIPLATELET ADEQUACY OF CYCLOPENTYL TRIAZOLOPYRIMIDINE VERSUS CLOPIDOGREL IN-PATIENTS WITH CORONARY HEART DISEASE

2018 ◽  
Vol 11 (12) ◽  
pp. 536
Author(s):  
Feryal Hashim Rada
Keyword(s):  
Platelet Aggregation ◽  
Stable Angina ◽  
Platelet Reactivity ◽  
Stable Coronary Artery Disease ◽  
Light Transmittance ◽  
Reactivity Index ◽  
Major Adverse Cardiovascular Events ◽  
Vasp Phosphorylation ◽  
Coronary Syndromes ◽  
Artery Disease

Objective: Ticagrelor, cyclopentyl triazolopyrimidine drug, and Clopidogrel, second-generation thienopyridine drug are antiplatelet drugs indicated for the prevention of thrombotic events in patients with acute or chronic coronary syndromes. The aim of this study is to assess efficacy and safety outcomes of ticagrelor treatment versus Clopidogrel treatment in patients with stable coronary artery disease (stable angina) using maximal platelet aggregation percent (MPAP) method and platelet reactivity index percent (PRIP) method.Methods: A total of 42 patients (27 male and 15 female), their ages ranging (48±8) years with stable angina enrolled from Ibn Albitar Center for Cardiac Surgery for this crossover study. After satisfying, the properties of inclusion criteria they screened for clopidogrel treatment 75 mg daily for 2 weeks than after 2 weeks periods of wash off they treated with ticagrelor 90 mg twice daily for another 2 weeks. Platelet reactivity was tested at baseline (before treatment), after 2 weeks treatment with clopidogrel and after another 2 weeks treatment with ticagrelor. Platelet reactivity measured by light transmittance aggregometry test and by vasodilator-stimulated phosphoprotein (VASP) phosphorylation test.Results: The results of MPAP after 2 weeks treatment with clopidogrel or ticagrelor showed high significant reduction in platelet aggregation in patients with ticagrelor treatment as compared to clopidogrel treatment (30±6% vs. 44±8%). As well, the results of PRIP using VASP-phosphorylation after 2 weeks treatment with clopidogrel or ticagrelor showed high significant reduction in platelet aggregation in patients with ticagrelor treatment as compared to clopidogrel treatment (22±5% vs. 36±7%).Conclusion: Treatment with ticagrelor produced a reduction in platelet reactivity consistent with the reduction in major adverse cardiovascular events and improved survival without increasing major bleeding.

Functional impact of high clopidogrel maintenance dosing in patients undergoing elective percutaneous coronary interventions

2008 ◽  
Vol 99 (01) ◽  
pp. 161-168 ◽  
Author(s):  
Esther Bernardo ◽  
Jorge Palazuelos ◽  
Bhaloo Desai ◽  
Ian Weisberg ◽  
Fernando Alfonso ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Maintenance Dose ◽  
Platelet Reactivity ◽  
Adenosine Diphosphate ◽  
Coronary Intervention ◽  
Platelet Inhibition ◽  
Relative Increase ◽  
Light Transmittance ◽  
Functional Impact ◽  
Percutaneous Coronary

SummaryThe currently recommended maintenance dose of clopidogrel is often associated with inadequate platelet inhibition, suggesting the need for a higher dose. The aim of this pilot study was to assess the functional impact of a high (150 mg/day) maintenance dose of clopidogrel in patients undergoing elective percutaneous coronary intervention (PCI).This is a prospective, randomized, platelet function study which was performed in elective PCI patients assigned to treatment with either a 75 mg (n=20) or 150 mg (n=20) daily maintenance dose of clopidogrel for 30 days;afterwards, all patients resumed standard dosing. Platelet aggregation was performed using light transmittance aggregometry following 20 μM and 5 μM adenosine diphosphate (ADP) stimuli 30 days after randomization and 30 days after resuming standard dosing. Patients treated with 150 mg/day clopidogrel had lower 20 μMADP-induced platelet aggregation compared to patients on 75 mg/day (52.1±9% vs. 64.0±8%; p<0.001; primary endpoint).The dose-dependent effect was confirmed by the absolute and relative increase in platelet aggregation after resuming standard dosing (p<0.001). No changes were observed in patients randomized to standard dosing. Parallel findings were observed following 5 μM ADP stimuli for all assessments. A broad variability in clopidogrel-induced antiplatelet effects was observed irrespective of dosing. In conclusion, a 150 mg/day maintenance dose regimen of clopidogrel is associated with reduced platelet reactivity and enhanced platelet inhibition compared to that achieved with the currently recommended 75 mg/day in patients undergoing elective PCI.

scholarly journals Comparison of Light Transmission Aggregometry With Impedance Aggregometry in Patients on Potent P2Y12 Inhibitors

2020 ◽  
pp. 107424842096870
Author(s):  
Patricia P. Wadowski ◽  
Joseph Pultar ◽  
Constantin Weikert ◽  
Beate Eichelberger ◽  
Irene M. Lang ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Light Transmission ◽  
Platelet Reactivity ◽  
Adenosine Diphosphate ◽  
P2y12 Inhibitors ◽  
Coronary Syndrome ◽  
Multiple Electrode Aggregometry ◽  
Impedance Aggregometry ◽  
Light Transmission Aggregometry ◽  
Sensitivity Specificity

Since data on the agreement between light transmission aggregometry (LTA) and multiple electrode aggregometry (MEA) in patients on the more potent P2Y12 inhibitors are missing so far, we investigated if the evaluation of the responsiveness to therapy by LTA can be replaced by MEA in 160 acute coronary syndrome (ACS) patients on dual antiplatelet therapy with aspirin and prasugrel or ticagrelor (n = 80 each). Cut-off values for high on-treatment residual platelet reactivity (HRPR) in response to adenosine diphosphate (ADP) or arachidonic acid (AA) were defined according to previous studies showing an association of HRPR with the occurrence of adverse ischemic outcomes. ADP- inducible platelet aggregation was 33% and 37% (p = 0.07) by LTA and 19 AU and 20 AU (p = 0.38) by MEA in prasugrel- and ticagrelor-treated patients, respectively. AA- inducible platelet aggregation was 2% and 3% by LTA and 15 AU and 16 AU by MEA, (all p ≥ 0.3) in patients on prasugrel and ticagrelor, respectively. By LTA, HRPR ADP and HRPR AA were seen in 5%/5% and in 4%/ 13% of patients receiving prasugrel- and ticagrelor, respectively. By MEA, HRPR ADP and HRPR AA were seen in 3%/ 25% and 0%/24% of prasugrel- and ticagrelor-treated patients, respectively. ADP-inducible platelet reactivity by MEA correlated significantly with LTA ADP in prasugrel-treated patients (r = 0.4, p < 0.001), but not in those receiving ticagrelor (r = 0.09, p = 0.45). AA-inducible platelet aggregation by LTA and MEA did not correlate in prasugrel- and ticagrelor-treated patients. Sensitivity/specificity of HRPR by MEA to detect HRPR by LTA were 25%/99% for MEA ADP and 100%/79% for MEA AA in prasugrel-treated patients, and 0%/100% for MEA ADP and 70%/83% for MEA AA in ticagrelor-treated patients. In conclusion, on-treatment residual ADP-inducible platelet reactivity by LTA and MEA shows a significant correlation in prasugrel- but not ticagrelor-treated patients. However, in both groups LTA and MEA revealed heterogeneous results regarding the classification of patients as responders or non-responders to P2Y12 inhibition.

Interactions Between Blood Platelets and Vascular Endothelium in vitro Studies

1979 ◽  
Author(s):  
M.A. Gimbrone ◽  
K.D. Curwen ◽  
R. I. Handin
Keyword(s):  
Platelet Aggregation ◽  
Vascular Endothelium ◽  
Potent Inhibitor ◽  
Platelet Reactivity ◽  
Blood Platelets ◽  
Primary Cultures ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Platelet Adherence

Endothelial cells (EC) can actively influence the hemostatic response at sites of vascular injury through multiple mechanisms. For example, EC can degrade adenosine diphosphate, release plasminogen activator, and synthesize prostacyclin (PGI2), a potent inhibitor of platelet aggregation. We have examined whether PGI2 also might account for the normal lack of platelet adherence to the uninjured EC surface. In a monolayer adherence assay, radiolabeled human platelets in citrated plasma showed minimal interaction with primary cultures of human EC (<1 platelet adhering per cell). Platelets from aspirin-treated and untreated donors behaved similarly. However, aspirin pretreatment of EC consistently resulted in ~2-fold increases in platelet adherence which could be completely abolished by exogenous PGI2 (0.5–1.0 μg/ml). SV40-transformed human EC (SVHEC), which are deficient in PGI2 production compared to primary EC, showed 10-30 times more platelet adherence. Exogenous PGI2 produced a dose - related (.001-1.0 μg/ml) decrease in platelet adherence to SVHEC but did not result in the basal levels observed with normal EC monolayers. These data suggest that : 1) In addition to its effects on platelet aggregation, PGI2 can influence platelet endothelial cell interactions; 2) The increased platelet reactivity of transformed EC is associated with, but not completely attributable, to decreased PGI2 production; and 3) Factors other than PGI2 may play a role in the thromboresistance of normal vascular endothelium.

Aprotinin: is it prothrombotic?

Perfusion ◽  
2001 ◽  
Vol 16 (5) ◽  
pp. 401-409 ◽  
Author(s):  
M Poullis ◽  
R C Landis ◽  
K M Taylor
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Mechanism Of Action ◽  
Adenosine Diphosphate ◽  
Platelet Membrane ◽  
Calcium Flux ◽  
Thrombin Receptor ◽  
Proteolytic Activation ◽  
Agonist Peptide ◽  
Receptor Family

Controversy continues as to whether aprotinin (Trasylol) is prothrombotic. The recent discovery of the thrombin receptor family, known as the protease-activated receptor family (PAR) has been essential in aiding our understanding of the mechanism of action of aprotinin. Our results show that aprotinin has no effect on platelet aggregation induced by adrenaline, adenosine diphosphate, phorbol-12-myristate-13-acetate, collagen or PAR 1 agonist peptide. However, aprotinin inhibits thrombin-induced platelet activation as assessed by macroaggregation, microaggregation and platelet membrane calcium flux. Aprotinin inhibits proteolytic activation of platelets, but platelets can still be activated by non-proteolytic mechanisms.

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