Comparison of a new P2Y12 receptor specific platelet aggregation test with other laboratory methods in stroke patients on clopidogrel monotherapy

PLoS One. 2013 Jul 2;8(7):e69417. doi: 10.1371/journal.pone.0069417. Print 2013.

Abstract

Background: Clinical studies suggest that 10-50% of patients are resistant to clopidogrel therapy. ADP induced platelet aggregation, a widely used test to monitor clopidogrel therapy, is affected by aspirin and is not specific for the P2Y12 receptor inhibited by clopidogrel.

Objectives: To develop a P2Y12-specific platelet aggregation test and to compare it with other methods used for monitoring clopidogrel therapy.

Patients/methods: Study population included 111 patients with the history of ischemic stroke being on clopidogrel monotherapy and 140 controls. The effect of clopidogrel was tested by a newly developed ADP(PGE1) aggregation test in which prostaglandin E1 treated platelets are used. Results of conventional ADP induced platelet aggregation, VerifyNow P2Y12 assay and ADP(PGE1) aggregation were compared to those obtained by flow cytometric analysis of vasodilator stimulated phosphoprotein (VASP) phosphorylation. Reference intervals for all assays were determined according to the guidelines of Clinical Laboratory Standards Institute.

Results: The P2Y12-specificity of ADP(PGE1) test was proven by comparing it with ADP aggregation in the presence of P2Y1 antagonist, adenosine 3', 5'-diphosphate. The method was not influenced by aspirin treatment. Approximately 50% of patients were clopidogrel resistant by conventional ADP aggregation and VerifyNow tests. The ADP(PGE1) method and the VASP phosphorylation assay identified 25.9% and 11.7% of patients as non-responders, respectively. ADP(PGE1) aggregation showed good correlation with VASP phosphorylation and had high diagnostic efficiency.

Conclusion: The new ADP(PGE1) method is a reliable test for monitoring P2Y12 receptor inhibition by platelet aggregation. As a subset of patients are non-responders, monitoring clopidogrel therapy by adequate methods is essential.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Diphosphate / pharmacology
  • Adult
  • Aged
  • Alprostadil / pharmacology
  • Blood Platelets / drug effects
  • Blood Platelets / metabolism
  • Cell Adhesion Molecules / metabolism
  • Clinical Laboratory Techniques / methods
  • Clopidogrel
  • Female
  • Flow Cytometry
  • Humans
  • Male
  • Microfilament Proteins / metabolism
  • Middle Aged
  • Phosphoproteins / metabolism
  • Phosphorylation / drug effects
  • Platelet Aggregation / drug effects*
  • Platelet Aggregation Inhibitors / pharmacology
  • Platelet Function Tests / methods
  • Purinergic P2Y Receptor Antagonists / therapeutic use
  • Receptors, Purinergic P2Y12 / metabolism*
  • Reproducibility of Results
  • Stroke / blood
  • Stroke / drug therapy*
  • Ticlopidine / analogs & derivatives*
  • Ticlopidine / therapeutic use

Substances

  • Cell Adhesion Molecules
  • Microfilament Proteins
  • Phosphoproteins
  • Platelet Aggregation Inhibitors
  • Purinergic P2Y Receptor Antagonists
  • Receptors, Purinergic P2Y12
  • vasodilator-stimulated phosphoprotein
  • Adenosine Diphosphate
  • Clopidogrel
  • adenosine 3'-phosphate-5'-phosphate
  • Alprostadil
  • Ticlopidine

Grants and funding

This work was supported by the National Office for Research and Technology (http://www.nfu.gov.hu) Jedlik Ányos program, DE-LABDIA, by the National Research Fund (www.otka.hu) (OTKA K78386), by the Hungarian Academy of Science (MTA11003, TKI227), by the National Development Agency (http://www.nfu.gov.hu) (TÁMOP projects 4.2.2.B-10/1-2010-0024, 4.2.2.A-11/1/KONV-2012-0045) and by the University of Debrecen, Medical and Health Science Center (http://www.med.unideb.hu) (MEC1/2011). Z. Bagoly is the recipient of János Bólyai fellowship and Lajos Szodoray Prize. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.