Document Detail

Aspirin resistance among long-term aspirin users after carotid endarterectomy and controls: flow cytometric measurement of aspirin-induced platelet inhibition.
MedLine Citation:
PMID:  17543677     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Numerous studies have indicated that some patient subpopulations do not respond to the antithrombotic effects of aspirin. The objective of this study was to evaluate aspirin-induced inhibition of platelet cyclooxygenase (COX) using a flow cytometric technique in long-term aspirin users after carotid endarterectomy (CEA) and controls with newly diagnosed carotid stenosis not taking aspirin and to compare these results with platelet function analyzer measurements.
METHODS: The study included 86 patients with a history of CEA on long-term aspirin therapy (100 mg daily) and 29 age-matched patients with newly diagnosed carotid artery stenosis not taking aspirin. Platelet-rich plasma diluted with phosphate-buffered saline was incubated with arachidonic acid (ARA) at a final concentration of 80 micromol/L. After staining with phycoerythrin-labeled anti-P-selectin (CD62p) antibody, platelet CD62p-antigen expression was measured on a flow cytometer.
RESULTS: Flow cytometric measurement of ARA-induced platelet activation showed an inhibition of ARA-induced platelet stimulation in all patients on aspirin therapy, whereas all but two controls (95%) showed expected platelet reactivity. In contrast, results of the platelet function analyzer measurements were normal in 16% of aspirin-treated patients.
CONCLUSIONS: Flow cytometric measurement of CD62p expression on platelets after incubation with ARA proved to be a practicable tool to monitor aspirin-induced inhibition of platelet COX. Results in patients on long-term low-dose aspirin therapy show that the inability of aspirin to inhibit platelet COX for both symptomatic and asymptomatic patients with high-grade internal carotid artery stenosis is a very rare event. So-called aspirin resistance detected quite frequently by platelet function analyzer measurement is most likely from COX-independent mechanisms.
Afshin Assadian; Jaqueline Lax; Ursula Meixner-Loicht; Georg W Hagmüller; Peter Michael Bayer; Wolfgang Hübl
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Journal of vascular surgery     Volume:  45     ISSN:  0741-5214     ISO Abbreviation:  J. Vasc. Surg.     Publication Date:  2007 Jun 
Date Detail:
Created Date:  2007-06-04     Completed Date:  2007-07-13     Revised Date:  2012-10-03    
Medline Journal Info:
Nlm Unique ID:  8407742     Medline TA:  J Vasc Surg     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1142-7; discussion 1147     Citation Subset:  IM    
Department of General and Vascular Surgery, Wilhelminenspital Vienna, Vienna, Austria.
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MeSH Terms
Arachidonic Acid / pharmacology
Aspirin / pharmacology,  therapeutic use*
Blood Platelets / drug effects*,  enzymology,  immunology
Carotid Stenosis / blood,  drug therapy*,  surgery
Case-Control Studies
Cyclooxygenase Inhibitors / pharmacology,  therapeutic use*
Drug Resistance*
Endarterectomy, Carotid
Fibrinolytic Agents / pharmacology,  therapeutic use*
Flow Cytometry*
P-Selectin / metabolism
Platelet Function Tests / methods*
Prostaglandin-Endoperoxide Synthases / metabolism
Severity of Illness Index
Reg. No./Substance:
0/Cyclooxygenase Inhibitors; 0/Fibrinolytic Agents; 0/P-Selectin; 50-78-2/Aspirin; 506-32-1/Arachidonic Acid; EC Synthases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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