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J Am Coll Cardiol. 2005 Nov 1;46(9):1705-9. Epub 2005 Oct 10.

Overestimation of platelet aspirin resistance detection by thrombelastograph platelet mapping and validation by conventional aggregometry using arachidonic acid stimulation.

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1
Sinai Center for Thrombosis Research, Baltimore, Maryland 21215, USA.

Abstract

OBJECTIVES:

This study sought to determine the prevalence of platelet aspirin resistance using methods that directly indicate the degree of platelet cyclooxygenase inhibition.

BACKGROUND:

Aspirin resistance in platelets may be overestimated by nonspecific laboratory measurements that do not isolate cyclooxygenase activity.

METHODS:

Arachidonic acid (AA)-induced light-transmittance platelet aggregation (LTA) and thrombelastography (TEG) platelet mapping were performed on the blood of healthy subjects (n = 6) before and 24 h after receiving 325 mg aspirin, and on 223 patients reporting compliance with long-term daily aspirin treatment (n = 203 undergoing percutaneous intervention [PCI] and n = 20 with a history of stent thrombosis). Aspirin resistance was defined as >20% aggregation by LTA or >50% aggregation by TEG.

RESULTS:

In healthy subjects, AA-induced aggregation by LTA was 82 +/- 10% before and 2 +/- 1% at 24 h after aspirin (p < 0.001), and aggregation by TEG was 86 +/- 14% before and 5 +/- 7% at 24 h after aspirin (p < 0.001). In compliant patients, AA-induced aggregation by LTA was 3 +/- 2% before PCI and 3 +/- 2% after PCI (p = NS), and aggregation by TEG was 5 +/- 9% before PCI and 6 +/- 14% after PCI (p = NS). Seven PCI patients were noncompliant, and all were aspirin sensitive after in-hospital aspirin treatment. Among 223 patients, only one patient ( approximately 0.4%) was resistant to aspirin treatment.

CONCLUSIONS:

Platelet aspirin resistance assessed by methods that directly indicate inhibition of cyclooxygenase is rare in compliant patients with coronary artery disease.

Comment in

PMID:
16256872
DOI:
10.1016/j.jacc.2005.05.090
[Indexed for MEDLINE]
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