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.

scholarly journals External Quality Assurance of Platelet Function Assays: Results of the College of American Pathologists Proficiency Testing Program

2018 ◽  
Vol 143 (4) ◽  
pp. 472-482 ◽  
Author(s):  
Wayne L. Chandler ◽  
Alan F. Brown ◽  
Dong Chen ◽  
Karen Moser ◽  
John D. Olson ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Proficiency Testing ◽  
Platelet Function ◽  
Adenosine Diphosphate ◽  
External Quality ◽  
Testing Data ◽  
Function Analyzer ◽  
Survey Responses ◽  
Platelet Function Analyzer ◽  
Platelet Function Assays

Context.—The College of American Pathologists (CAP) developed proficiency testing for platelet function assays by using blood collected by the participant added to challenge tubes containing either saline (normal) or tirofiban (abnormal).Objective.—To analyze platelet function proficiency testing for Platelet Function Analyzer PFA-100, platelet aggregation, PlateletWorks, and PlateletMapping.Design.—Proficiency testing data from 2012–2016 were analyzed.Results.—For PFA-100, a total of 1200 laboratories participated; the coefficient variation (CV) of cartridge closure times was 22% (saline); 44,952 of 45,616 survey responses (99%) provided an interpretation, and 42,934 of 44,952 (96%) were correct. For optical platelet aggregation, 190 laboratories participated; the CV was 17% (saline), 7444 of 7813 survey responses (95%) provided an interpretation, and 7015 of 7444 (94%) were correct. For PlateletWorks, 60 laboratories participated; the CV was 3% to 11% (saline); 2412 of 2454 survey responses (98%) provided an interpretation, and 1207 of 1276 (95%) were correct for adenosine diphosphate (ADP) and 936 of 1136 (82%) for collagen. For PlateletMapping, 200 laboratories participated. For ADP, 1128 of 2697 survey responses (42%) provided an interpretation, but only 927 of 1128 (82%) were correct. For arachidonic acid, 1139 of 2604 survey responses (44%) provided an interpretation and 964 of 1139 (85%) were correct.Conclusions.—CAP is the first to provide proficiency testing for platelet aggregation, PlateletWorks, and PlateletMapping. Platelet aggregation, PFA-100, and PlateletWorks using ADP as an agonist performed well with more than 90% of laboratories providing an interpretation and a similar number providing correct results. PlateletWorks using collagen and PlateletMapping showed worse interpretive accuracy than the other methods.

scholarly journals Adequate Platelet Function Inhibition Confirmed by Two Inductive Agents Predicts Lower Recurrence of Ischemic Stroke/Transient Ischemic Attack

2017 ◽  
Vol 2017 ◽  
pp. 1-5 ◽  
Author(s):  
Lulu Zhang ◽  
Xiaowei Hu ◽  
Juehua Zhu ◽  
Xiuying Cai ◽  
Yan Kong ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Antiplatelet Therapy ◽  
Platelet Function ◽  
Adenosine Diphosphate ◽  
Aggregation Rate ◽  
Function Analyzer ◽  
Ischemic Attack ◽  
Platelet Function Analyzer ◽  
Platelet Functions

Background. The correlation between platelet function and recurrent ischemic stroke or TIA remains uncertain. Objective. To investigate two inductive agents to detect platelet functions and assess associations with recurrent ischemic stroke/TIA. Method. The study included 738 ischemic stroke/TIA patients. On days 0, 3, and 9 after antiplatelet therapy, platelet function tests were determined by maximum aggregation rate (MAR) using a PL-11 platelet function analyzer and phase matching reagents. Two induction agents were used: arachidonic acid (AA) and adenosine diphosphate (ADP). At 3-month follow-up, recurrence of stroke/TIA was recorded. Result. Cut-off values of adequate platelet function inhibition were MARADP < 35% and MARAA < 35%. Data showed that antiplatelet therapy could reduce the maximum aggregation rate. More importantly, adequate platelet function inhibition of either MARADP or MARAA was not associated with the recurrence of stroke/TIA, but adequate platelet function inhibition of not only MARADP but also MARAA predicts lower recurrence (0/121 (0.00%) versus 18/459 (3.92%), P = 0.0188). Conclusion. The platelet function tested by PL-11 demonstrated that adequate inhibition of both MARADP and MARAA could predict lower risk of ischemic stroke/TIA recurrence.

scholarly journals Platelet Function Disturbance During Veno-Venous ECMO in ARDS Patients Assessed by Multiple Electrode Aggregometry—A Prospective, Observational Cohort Study

2019 ◽  
Vol 8 (7) ◽  
pp. 1056 ◽  
Author(s):  
Saskia Wand ◽  
Jan Felix Huber-Petersen ◽  
Joern Schaeper ◽  
Claudia Binder ◽  
Onnen Moerer
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Extracorporeal Circulation ◽  
Inverse Correlation ◽  
Negative Effects ◽  
Multiple Electrode Aggregometry ◽  
Observational Cohort ◽  
And Function ◽  
The Impact ◽  
Multiple Electrode

Extracorporeal (veno-venous) membrane oxygenation (vvECMO) has been shown to have negative effects on platelet number and function. This study aimed to gain more information about the impact of vvECMO on platelet function assessed by multiple electrode aggregometry (MEA). Twenty patients with the indication for vvECMO were included. Platelet function was analyzed using MEA (Multiplate®) before (T-1), 6 h (T0), one (T1), two (T2), three (T3), and seven (T4) days after the beginning of vvECMO. Median aggregational measurements were already below the normal reference range before vvECMO initiation. Platelet aggregation was significantly reduced 6 h after vvECMO initiation compared to T-1 and spontaneously recovered with a significant increase at T2. Platelet count dropped significantly between T-1 and T0 and continuously decreased between T0 and T4. At T4, ADP-induced platelet aggregation showed an inverse correlation with the paO2 in the oxygenator. Platelet function should be assessed by MEA before the initiation of extracorporeal circulation. Although ECMO therapy led to a further decrease in platelet aggregation after 6 h, all measurements had recovered to baseline on day two. This implies that MEA as a whole blood method might not adequately reflect the changes in platelet function in the later stages of extracorporeal circulation.

scholarly journals Monitoring of Clopidogrel Action: Comparison of Methods

2005 ◽  
Vol 51 (6) ◽  
pp. 957-965 ◽  
Author(s):  
Jörg Geiger ◽  
Lino Teichmann ◽  
Ralf Grossmann ◽  
Barsom Aktas ◽  
Udo Steigerwald ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Platelet Function ◽  
Significant Proportion ◽  
Coronary Intervention ◽  
Platelet Response ◽  
Closure Time ◽  
Vasp Phosphorylation ◽  
Function Analyzer ◽  
Potent Drug ◽  
Platelet Function Analyzer

Abstract Background: Clopidogrel is a potent drug for prevention of adverse effects during and after coronary intervention. Increasing experience indicates that a significant proportion of patients do not respond adequately to clopidogrel. Because failure of antiplatelet therapy can have severe consequences, there is need for a reliable assay to quantify the effectiveness of clopidogrel treatment. Methods: Of 24 healthy volunteers admitted to the study, 18 were treated for 1 week with clopidogrel (300-mg loading dose and 75-mg maintenance dose), and 6 with placebo. Platelet function was monitored by 2 assays, based on flow cytometry and enzyme immunoassay, that measure the phosphorylation status of vasodilator-stimulated phosphoprotein (VASP) and by aggregometry, flow cytometry of P-selectin, and the platelet function analyzer at baseline, on days 1–5, and on day 9 of treatment. Results: Aggregometry and VASP phosphorylation revealed a loss of platelet response to ADP within 12 h after clopidogrel intake. The phosphorylation status of VASP correlated with the inhibition of platelet aggregation. In contrast, neither P-selectin expression nor PFA-100 closure time was a clear indicator of clopidogrel effects on platelets. Conclusions: VASP phosphorylation assays are reliable for quantifying clopidogrel effects. Because the VASP assay directly measures the function of the clopidogrel target, the P2Y12 receptor, the assay is selective for clopidogrel effects rather than effects of other platelet inhibitors commonly in use.

Sevoflurane Inhibits Unstimulated and Agonist-induced Platelet Antigen Expression and Platelet Function in Whole Blood In Vitro 

2001 ◽  
Vol 95 (5) ◽  
pp. 1220-1225 ◽  
Author(s):  
Nicola A. Horn ◽  
Lothar de Rossi ◽  
Tilo Robitzsch ◽  
Klaus E. Hecker ◽  
Gabriele Hutschenreuter ◽  
...  
Keyword(s):  
Platelet Function ◽  
Whole Blood ◽  
Control Sample ◽  
Antigen Expression ◽  
Adenosine Diphosphate ◽  
Color Flow ◽  
Platelet Antigen ◽  
Function Analyzer ◽  
Platelet Function Analyzer

Background Previous studies have reported conflicting results about the effect of sevoflurane on platelet aggregation. To clarify this point, we investigated the effects of sevoflurane on platelet antigen expression and function in vitro. Methods Human whole blood was incubated for 1 h with 0.5 and 1 minimum alveolar concentration sevoflurane, 21% O(2), and 5% CO(2). A control sample was kept at the same conditions without sevoflurane. After stimulation with adenosine diphosphate or thrombin receptor agonist peptide 6, samples were stained with fluorochrome conjugated antibodies, and the expression of platelet glycoproteins GPIIb/IIIa, GPIb, and P-selectin, as well as activated GPIIb/IIIa, were measured with two-color flow cytometry. In addition, platelet function was assessed by means of thromboelastography and using the platelet function analyzer 100. Results Already in subanesthetic concentrations, sevoflurane inhibits unstimulated and agonist-induced GPIIb/IIIa surface expression and activated GPIIb/IIIa expression on platelets in whole blood. The agonist-induced redistribution of GPIb into the open canalicular system was also impaired by sevoflurane, whereas no effect on P-selectin expression in activated platelets could be found. Sevoflurane significantly reduced the maximum thromboelastographic amplitude. Furthermore, platelet function analyzer 100 closure times were significantly prolonged. Conclusion The results show that sevoflurane significantly impairs platelet antigen expression in vitro. It is especially the inhibition of GPIIb/IIIa expression and activation that impairs bleeding time as reflected in thromboelastographic measurements and platelet function analyzer 100 closure times. The exact inhibitory mechanism remains unclear.

scholarly journals Comparison of farmacodynamic properties of three different aspirin formualtions in patients with stable coronary disease

2019 ◽  
Vol 76 (6) ◽  
pp. 628-634
Author(s):  
Ana Antic ◽  
Zoran Stanojkovic ◽  
Miodrag Vucic ◽  
Milan Lazarevic ◽  
Nebojsa Vacic
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Dual Therapy ◽  
Impedance Aggregometry ◽  
Measured Time ◽  
Function Analyzer ◽  
Group 3 ◽  
Group 2 ◽  
Platelet Function Analyzer ◽  
Group 1

Background/Aim. The platelet aggregation, as a laboratory test for assessment of platelet function, is very efficient for optimal antiplatelet treatment and also to identify individuals who have suboptimal response to antiplatelet drugs, such as aspirin and clopidogrel. The aim of this study was to determine the level of inhibition of platelet aggregation using impedance aggregometry in the patients receiving different preparations of acetylsalicylic acid (ASA) in a dose of 100 mg per day. Methods. The examination included 215 patients (110 men and 105 women), treated with one of three different ASA preparations after acute myocardial infarction, as a single therapy or with clopidogrel. Among them, 89 patients were on Aspirin protect? (Bayer, Germany) ? Group 1 and 66 patients were on Cardiopirin? (GL Pharma GMBH, Austria) ? Group 2, while 60 patients were taking Andol? (Pliva, Croatia) ? Group 3. The groups were equal in the presence of factors that can influence platelet aggregation (age, gender, smoking, diabetes, taking other drugs). The platelet function was measured using the impedance aggregometer Multiplate (Multiplate Platelet Function Analyzer, Roche) in the blood samples with heparin for the platelet aggregation activated by the arachidonic acid (ASPI) and by thrombin (TRAP) tests [the area under the aggregation curve (AUC) was used to express the aggregation response over the measured time (AU*min)]. Results. Efficacy of ASA preparations showed statistically significant differences among the three investigated groups (?KW2 = 46.279; p < 0.001), and it was also observed separately in the patients undergoing single therapy (?KW2 = 26.344; p < 0.001) and dual therapy (?KW2 = 23.498; p < 0.001). It was found that the patients who were taking Aspirin protect? obtained significantly better antiplatelet efficiency compared to the patients receiving Cardiopirin? (Z = 5.472; p < 0.001) and Andol? (Z = 5.387; p = 0.022). There is reduced efficiency of all ASA preparations in smokers, while patients receiving Aspirin protect? were 10.5 times more likely to be responders. Conclusion. Different ASA preparations observed in this study showed different efficiency on the platelet function as measured by the method of impedance aggregometry.

Platelet function in cats with hyperthyroidism

2020 ◽  
Vol 22 (12) ◽  
pp. 1214-1218
Author(s):  
Elizabeth C Hiebert ◽  
David L Panciera ◽  
Katie M Boes ◽  
Lara Bartl
Keyword(s):  
Platelet Count ◽  
Platelet Function ◽  
Adenosine Diphosphate ◽  
Control Group ◽  
Closure Time ◽  
Function Analyzer ◽  
The Mean ◽  
Platelet Function Analyzer ◽  
Von Willebrand ◽  
Willebrand Factor

Objectives Cats with hyperthyroidism have been reported to develop thromboembolism, with and without echocardiographic abnormalities consistent with hyperthyroidism. The objective of this study was to compare platelet function in cats with hyperthyroidism with euthyroid age-matched cats. We hypothesized that cats with hyperthyroidism have shortened collagen and adenosine diphosphate (C-ADP) closure times as measured with the platelet function analyzer (PFA-100) in comparison with healthy, age-matched controls. Methods Sixteen hyperthyroid and nine euthyroid healthy cats >7 years of age were recruited from the hospital population. Platelet function, measured using the C-ADP closure times by the PFA-100, and platelet count were measured in healthy euthyroid cats and cats with hyperthyroidism. Results Mean ± SD closure times were not significantly different between control (66.3 ± 9.6 s) and hyperthyroid cats (65.9 ± 11.5 s; P = 0.75). The mean ± SD closure times of hyperthyroid cats that either were untreated or received methimazole for ⩽3 weeks (n = 6; mean 68.5 ± 15.4 s) was not different than that of cats treated for >3 weeks (n = 10; mean 64.3 ± 8.9 s; P = 0.57). The mean automated platelet count was higher in the hyperthyroid group than in the control group ( P = 0.023). Conclusions and relevance Platelet function, as measured by closure time under high shear conditions using C-ADP as an agonist, was not affected by hyperthyroidism in this group of cats. Further research is needed to determine if a hypercoagulable state exists in hyperthyroid cats and the potential roles platelets and von Willebrand factor may have.

Stability of the high on-treatment platelet reactivity phenotype over time in clopidogrel-treated patients

2011 ◽  
Vol 105 (01) ◽  
pp. 107-112 ◽  
Author(s):  
Juliane Jaitner ◽  
Julia Stegherr ◽  
Tanja Morath ◽  
Siegmund Braun ◽  
Isabell Bernlochner ◽  
...  
Keyword(s):  
Platelet Function ◽  
Large Scale ◽  
Light Transmission ◽  
Platelet Reactivity ◽  
Adenosine Diphosphate ◽  
Antiplatelet Treatment ◽  
Chi Square ◽  
Multiple Electrode Aggregometry ◽  
The Stability ◽  
Over Time

SummaryInterindividual response variability to clopidogrel treatment is a well established phenomenon. In recent studies and ongoing large-scale trials where patients with high on-treatment platelet reactivity (HPR) to clopidogrel are being randomised to an intensified antiplatelet treatment, confirmation of the HPR phenotype is based on one single platelet function assessment. The stability of the HPR phenotype over time has never been investigated but should be considered crucial for justification of intensified antiplatelet treatment regimens beyond clinical trials. The goal of this study was to test for the stability of the HPR phenotype over time in clopidogrel-treated patients. Patients (n=31) under chronic clopidogrel treatment (75 mg/day) were investigated by serial adenosine diphosphate (ADP)-induced platelet aggregation assessment with multiple electrode aggregometry (MEA) on a Multiplate analyser and light transmission aggregometry (LTA) at three different time points (once per week) during monitored antiplatelet treatment. On the basis of a cut-off level approach (468 AU*min for MEA, 53% for LTA) patients were classified into patients with (n=27) or without (n=4) HPR. For MEA, the phenotype was stable in 93.5% (n=29) of patients whereas 6.5% (n=2) crossed the cut-off level. For LTA, the phenotype was stable in 68% (n=21) of patients whereas 32% (n=10) patients crossed the cut-off level (chi-square P=0.01 for comparison of pheno-type stability between both assays). In conclusion, the HPR phenotype is stable over time in the majority of clopidogrel-treated patients. Comparative assessment of phenotype stability across available platelet function assays warrants further investigation.

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