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Static platelet adhesion, flow cytometry and serum TXB2 levels for monitoring platelet inhibiting treatment with ASA and clopidogrel in coronary artery disease: a randomised cross-over study.

ABSTRACT: BACKGROUND: Despite the use of anti-platelet agents such as acetylsalicylic acid (ASA) and clopidogrel in coronary heart disease, some patients continue to suffer from atherothrombosis. This has stimulated development of platelet function assays to monitor treatment effects. However, it is still not recommended to change treatment based on results from platelet function assays. This study aimed to evaluate the capacity of a static platelet adhesion assay to detect platelet inhibiting effects of ASA and clopidogrel. The adhesion assay measures several aspects of platelet adhesion simultaneously, which increases the probability of finding conditions sensitive for anti-platelet treatment. METHODS: With a randomised cross-over design we evaluated the anti-platelet effects of ASA combined with clopidogrel as well as monotherapy with either drug alone in 29 patients with a recent acute coronary syndrome. Also, 29 matched healthy controls were included to evaluate intra-individual variability over time. Platelet function was measured by flow cytometry, serum thromboxane B2 (TXB2)-levels and by static platelet adhesion to different protein surfaces. The results were subjected to Principal Component Analysis followed by ANOVA, t-tests and linear regression analysis. RESULTS: The majority of platelet adhesion measures were reproducible in controls over time denoting that the assay can monitor platelet activity. Adenosine 5'-diphosphate (ADP)-induced platelet adhesion decreased significantly upon treatment with clopidogrel compared to ASA. Flow cytometric measurements showed the same pattern (r2 = 0.49). In opposite, TXB2-levels decreased with ASA compared to clopidogrel. Serum TXB2 and ADP-induced platelet activation could both be regarded as direct measures of the pharmacodynamic effects of ASA and clopidogrel respectively. Indirect pharmacodynamic measures such as adhesion to albumin induced by various soluble activators as well as SFLLRN-induced activation measured by flow cytometry were lower for clopidogrel compared to ASA. Furthermore, adhesion to collagen was lower for ASA and clopidogrel combined compared with either drug alone. CONCLUSION: The indirect pharmacodynamic measures of the effects of ASA and clopidogrel might be used together with ADP-induced activation and serum TXB2 for evaluation of anti-platelet treatment. This should be further evaluated in future clinical studies where screening opportunities with the adhesion assay will be optimised towards increased sensitivity to anti-platelet treatment.

SUBMITTER: Eriksson AC

PROVIDER: S-EPMC2699331 | biostudies-literature | 2009

REPOSITORIES: biostudies-literature

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Static platelet adhesion, flow cytometry and serum TXB2 levels for monitoring platelet inhibiting treatment with ASA and clopidogrel in coronary artery disease: a randomised cross-over study.

Eriksson Andreas C AC Jonasson Lena L Lindahl Tomas L TL Hedbäck Bo B Whiss Per A PA

Journal of translational medicine 20090609

<h4>Background</h4>Despite the use of anti-platelet agents such as acetylsalicylic acid (ASA) and clopidogrel in coronary heart disease, some patients continue to suffer from atherothrombosis. This has stimulated development of platelet function assays to monitor treatment effects. However, it is still not recommended to change treatment based on results from platelet function assays. This study aimed to evaluate the capacity of a static platelet adhesion assay to detect platelet inhibiting effe ...[more]

PMID: 19508722

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Project description:BackgroundPrevious studies have shown that flow cytometry is a reliable test to quantify platelet function in stored platelet concentrates (PC). It is thought that flow cytometry is laborious and hence expensive. We have optimized the flow cytometry-based quantification of agonist induced platelet activation (PACT) to a labor, time and more cost-efficient test. Currently the quality of PCs is only monitored by visual inspection, because available assays are unreliable or too laborious for use in a clinical transfusion laboratory. Therefore, the PACT was applied to monitor PC activation during storage.Study design and methodsThe optimized PACT was used to monitor 5 PCs during 10 days of storage. In brief, optimized PACT uses a ready-to-use reaction mix, which is stable at -20°C. When needed, a test strip is thawed and platelet activation is initiated by mixing PC with PACT. PACT was based on the following agonists: adenosine diphosphate (ADP), collagen-related peptide (CRP) and thrombin receptor-activating peptide (TRAP-6). Platelet activation was measured as P-selectin expression. Light transmission aggregometry (LTA) was performed as a reference.ResultsBoth PACT and LTA showed platelet function decline during 10-day storage after stimulation with ADP and collagen/CRP; furthermore, PACT showed decreasing TRAP-induced activation. Major differences between the two tests are that PACT is able to measure the status of platelets in the absence of agonists, and it can differentiate between the number of activated platelets and the amount of activation, whereas LTA only measures aggregation in response to an agonist. Also, PACT is more time-efficient compared to LTA and allows high-throughput analysis.ConclusionPACT is an optimized platelet function test that can be used to monitor the activation of PCs. PACT has the same accuracy as LTA with regard to monitoring PCs, but it is superior to both LTA and conventional flow cytometry based tests with regard to labor-, time- and cost efficiency.

Project description:Background: The combination of clopidogrel and aspirin is recommended for the treatment of patients with acute minor stroke or transient ischemic attack (TIA). However, with varied clopidogrel resistance (often due to CYP2C19 loss-of-function (LOF) alleles), alternatives like ticagrelor have been suggested. Previous studies showed that ticagrelor had a lower platelet reactivity assessed by VerifyNow P2Y12 assay than clopidogrel. We aimed to compare the effect of ticagrelor vs. clopidogrel on platelet reactivity assessed by a different method (Aggrestar platelet function analyzer) and analyze whether CYP2C19 genotypes were involved. Methods: A pre-specified subgroup analysis of a randomized controlled trial- Platelet Reactivity in Acute Non-disabling Cerebrovascular Events (PRINCE) was conducted. Patients with minor stroke or TIA were randomized for treatment with ticagrelor plus aspirin or clopidogrel plus aspirin. Platelet reactivity was assessed by Aggrestar (PL) platelet function analyzer and high on-treatment platelet reactivity (HOPR) on ticagrelor or clopidogrel was compared. Clinical outcomes included any stroke, composite vascular events and bleeding events within 90 days. Patients were categorized into carriers and non-carriers according to the carrier status of CYP2C19 LOF alleles. Results: Among 675 patients enrolled in the PRINCE trial, 387 patients were included in this subgroup: 197 were randomized to ticagrelor plus aspirin and 190 to clopidogrel plus aspirin. At 90 ± 7 days, compared with clopidogrel/aspirin group, the proportion of HOPR in ticagrelor/aspirin group was significantly lower (19.6 vs. 40.8%, P < 0.001). No significant treatment-by-genotype interactions were found (P for interaction = 0.12). Within 90 days, a trend toward a lower risk of new stroke in ticagrelor/aspirin compared to clopidogrel/aspirin was observed (4.6 vs. 9.5%, HR 0.47, 95% CI 0.21-1.05, P = 0.06). Conclusions: Ticagrelor is superior to clopidogrel in inhibiting platelet reactivity measured by the PL platelet function analyzer among patients with acute minor stroke or TIA. Our study confirmed the finding of the main analysis of PRINCE trial in a different assay. Large randomized controlled trials are needed to evaluate our findings. Clinical Trial Registration: Clinicaltrials.gov NCT02506140.

Dataset Information

Static platelet adhesion, flow cytometry and serum TXB2 levels for monitoring platelet inhibiting treatment with ASA and clopidogrel in coronary artery disease: a randomised cross-over study.

Publications

Static platelet adhesion, flow cytometry and serum TXB2 levels for monitoring platelet inhibiting treatment with ASA and clopidogrel in coronary artery disease: a randomised cross-over study.

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