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Thromboelastography: potential bedside tool to assess the effects of antiplatelet therapy?

Thromboelastography: potential bedside tool to assess the effects of antiplatelet therapy?
Thromboelastography: potential bedside tool to assess the effects of antiplatelet therapy?
Modified thrombelastography (TEG) is a simple point of care test that provides an overall assessment of ex vivo clot formation and currently has limited clinical application. We evaluated the ability of TEG to assess the effects of antiplatelet therapy on clot formation using a novel assessment parameter (the area under curve). Forty healthy volunteers were divided into four groups of 10. Group A took aspirin 75 mg once daily for 7 days followed by aspirin 75 mg and clopidogrel 75 mg once daily in combination for 7 more days. Blood samples were taken for analysis at day 0 and days 7 and 14. Group B took a single 300 mg dose of aspirin. Group C took 600 mg of clopidogrel only. Group D took 300 mg of aspirin and 600 mg of clopidogrel at the same time. For groups B, C and D blood was taken prior to drug administration and at 2, 6 and 24 h afterwards. Each sample was tested by TEG in four channels following activation using (1) kaolin, (2) activator F (Act F), a direct activator of fibrin, (3) Act F + arachidonic acid (AA) and (4) Act F + adenosine diphosphate (ADP). Parameters measured included the maximum amplitude (MA) of the clot and the area under the TEG-generated curve at 1 h. Significant, time-dependent reductions in MA and area were seen in the AA-activated samples following administration of aspirin in all groups as compared to baseline. By contrast, there were no significant differences in MA or area in the AA-activated samples with clopidogrel alone. Significant reductions were also seen in MA and area in ADP-activated samples from volunteers treated with clopidogrel as compared to baseline. Three out of 10 subjects receiving 600 mg clopidogrel had a reduction in their responses of 30% or less, thus identifying them as relatively resistant to the drug. This study identifies a rapid, reliable method for assessing the time-dependent effects of antiplatelet therapy on clotting using a novel parameter of area of the TEG trace, which could have an important clinical application as a point of care test of efficacy, particularly in the context of acute coronary syndromes and percutaneous coronary intervention.
thromboelastography, antiplatelet therapy
0953-7104
385-392
Swallow, R.A.
185f7e0f-d632-4dfa-95c5-e98d6ca2e6c7
Agarwala, R.A.
bcbe4390-3406-4138-a745-8226768c98c7
Dawkins, K.D.
528a45bb-0158-4dbf-af28-2a64d43244e3
Curzen, N.P.
70f3ea49-51b1-418f-8e56-8210aef1abf4
Swallow, R.A.
185f7e0f-d632-4dfa-95c5-e98d6ca2e6c7
Agarwala, R.A.
bcbe4390-3406-4138-a745-8226768c98c7
Dawkins, K.D.
528a45bb-0158-4dbf-af28-2a64d43244e3
Curzen, N.P.
70f3ea49-51b1-418f-8e56-8210aef1abf4

Swallow, R.A., Agarwala, R.A., Dawkins, K.D. and Curzen, N.P. (2006) Thromboelastography: potential bedside tool to assess the effects of antiplatelet therapy? Platelets, 17 (6), 385-392. (doi:10.1080/09537100600757521).

Record type: Article

Abstract

Modified thrombelastography (TEG) is a simple point of care test that provides an overall assessment of ex vivo clot formation and currently has limited clinical application. We evaluated the ability of TEG to assess the effects of antiplatelet therapy on clot formation using a novel assessment parameter (the area under curve). Forty healthy volunteers were divided into four groups of 10. Group A took aspirin 75 mg once daily for 7 days followed by aspirin 75 mg and clopidogrel 75 mg once daily in combination for 7 more days. Blood samples were taken for analysis at day 0 and days 7 and 14. Group B took a single 300 mg dose of aspirin. Group C took 600 mg of clopidogrel only. Group D took 300 mg of aspirin and 600 mg of clopidogrel at the same time. For groups B, C and D blood was taken prior to drug administration and at 2, 6 and 24 h afterwards. Each sample was tested by TEG in four channels following activation using (1) kaolin, (2) activator F (Act F), a direct activator of fibrin, (3) Act F + arachidonic acid (AA) and (4) Act F + adenosine diphosphate (ADP). Parameters measured included the maximum amplitude (MA) of the clot and the area under the TEG-generated curve at 1 h. Significant, time-dependent reductions in MA and area were seen in the AA-activated samples following administration of aspirin in all groups as compared to baseline. By contrast, there were no significant differences in MA or area in the AA-activated samples with clopidogrel alone. Significant reductions were also seen in MA and area in ADP-activated samples from volunteers treated with clopidogrel as compared to baseline. Three out of 10 subjects receiving 600 mg clopidogrel had a reduction in their responses of 30% or less, thus identifying them as relatively resistant to the drug. This study identifies a rapid, reliable method for assessing the time-dependent effects of antiplatelet therapy on clotting using a novel parameter of area of the TEG trace, which could have an important clinical application as a point of care test of efficacy, particularly in the context of acute coronary syndromes and percutaneous coronary intervention.

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More information

Published date: September 2006
Keywords: thromboelastography, antiplatelet therapy

Identifiers

Local EPrints ID: 61548
URI: http://eprints.soton.ac.uk/id/eprint/61548
ISSN: 0953-7104
PURE UUID: 3eabfa2f-2e60-451a-a27f-7318b51ce247
ORCID for N.P. Curzen: ORCID iD orcid.org/0000-0001-9651-7829

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Date deposited: 03 Oct 2008
Last modified: 16 Mar 2024 03:45

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Contributors

Author: R.A. Swallow
Author: R.A. Agarwala
Author: K.D. Dawkins
Author: N.P. Curzen ORCID iD

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