Comparison of methods to evaluate clopidogrel-mediated platelet inhibition after percutaneous intervention with stent implantation

Thromb Haemost. 2009 Feb;101(2):333-9.


A high on-treatment residual ADP-inducible platelet reactivity in light transmission aggregometry (LTA) has been associated with an increased risk of adverse outcomes after percutaneous coronary intervention (PCI). However, LTA is weakly standardized, and results obtained in one laboratory may not be comparable to those obtained in another one. We therefore sought to determine the test correlating best with LTA to estimate clopidogrel-mediated platelet inhibition in 80 patients on dual antiplatelet therapy after elective percutaneous intervention with stent implantation. We selected the VerifyNow P2Y12 assay, the vasodilator-stimulated phosphoprotein phosphorylation assay, multiple electrode platelet aggregometry and the Impact-R for comparisons with LTA. Cut-off values for residual ADP-inducible platelet reactivity were defined according to quartiles of each assay. Sensitivities and specificities of the different platelet function tests were based on the results from LTA. The results from all four assays correlated significantly with those from LTA. The VerifyNow P2Y12 assay revealed the strongest correlation (r = 0.61, p < 0.001). Sensitivities and specificities ranged from 35% to 55%, and from 78.3% to 85%, respectively. In conclusion, although all assays correlated significantly with LTA, they need to be improved to become clinically used diagnostic tests. Further, it may be too early to define the gold standard method for assessing residual ADP-inducible platelet reactivity and generally acceptable cut-off values.

Publication types

  • Clinical Trial
  • Comparative Study

MeSH terms

  • Adenosine Diphosphate
  • Adult
  • Aged
  • Aged, 80 and over
  • Angioplasty, Balloon, Coronary / adverse effects
  • Angioplasty, Balloon, Coronary / instrumentation*
  • Aspirin / therapeutic use*
  • Cardiovascular Diseases / blood
  • Cardiovascular Diseases / etiology
  • Cardiovascular Diseases / prevention & control*
  • Cell Adhesion Molecules / blood
  • Clopidogrel
  • Drug Resistance
  • Drug Therapy, Combination
  • Female
  • Humans
  • Male
  • Microfilament Proteins / blood
  • Middle Aged
  • Phosphoproteins / blood
  • Phosphorylation
  • Platelet Activation / drug effects*
  • Platelet Aggregation / drug effects
  • Platelet Aggregation Inhibitors / therapeutic use*
  • Platelet Function Tests* / standards
  • Predictive Value of Tests
  • Purinergic P2 Receptor Antagonists
  • Receptors, Purinergic P2 / blood
  • Receptors, Purinergic P2Y12
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Stents*
  • Ticlopidine / analogs & derivatives*
  • Ticlopidine / therapeutic use


  • Cell Adhesion Molecules
  • Microfilament Proteins
  • P2RY12 protein, human
  • Phosphoproteins
  • Platelet Aggregation Inhibitors
  • Purinergic P2 Receptor Antagonists
  • Receptors, Purinergic P2
  • Receptors, Purinergic P2Y12
  • vasodilator-stimulated phosphoprotein
  • Adenosine Diphosphate
  • Clopidogrel
  • Ticlopidine
  • Aspirin