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Updated: Jul 12, 2026

Microfluidics in Assessing Platelet Function
Published on: November 8, 2024
Different methodologies for evaluating the effect of clopidogrel on platelet function in high-risk coronary artery
R Paniccia1, E Antonucci, A M Gori
1Department of Medical and Surgical Critical Care, Thrombosis Centre, University of Florence, Florence, Itlay. rita.paniccia@unifi.it
Insights
The VerifyNow assay correlates well with light transmission aggregation for measuring residual platelet reactivity in coronary artery disease patients. However, the Platelet Function Analyzer-100 (PFA-100) assay did not show significant correlation, indicating a need for further clinical validation of point-of-care systems.
Area of Science:
- Cardiology
- Clinical Chemistry
- Pharmacology
Background:
- Point-of-care (POC) systems offer rapid assessment of residual platelet reactivity (RPR).
- Coronary artery disease (CAD) patients on dual antiplatelet therapy require monitoring of platelet function.
Purpose of the Study:
- Compare the Platelet Function Analyzer-100 (PFA-100) and VerifyNow P2Y12 assays against light transmission aggregation (LTA).
- Evaluate the utility of these POC systems in assessing RPR in CAD patients.
Main Methods:
- 1267 CAD patients undergoing percutaneous coronary intervention were studied.
- PFA-100 closure times (CTs) and VerifyNow P2Y12 Assay results were compared with LTA induced by ADP (2 and 10 micromol L(-1)).
- Vaso-dilator-stimulated phosphoprotein (VASP) phosphorylation assay was performed in a subgroup.
Main Results:
- VerifyNow showed significant correlation and agreement with LTA (2 and 10 micromol L(-1) ADP).
- PFA-100 C/ADP CT results did not correlate significantly with LTA.
- VASP platelet reactivity index correlated significantly with both ADP-LTA and VerifyNow.
Conclusions:
- The VerifyNow assay demonstrates good correlation with LTA for RPR assessment.
- The PFA-100 C/ADP assay is not a reliable alternative to LTA in this patient group.
- Further clinical validation of POC systems for RPR monitoring is essential.
Background:
Two point-of-care (POC) systems have been recently proposed as rapid tools with which to evaluate residual platelet reactivity (RPR) in coronary artery disease (CAD) patients.
Objectives And Methods:
We compared Platelet Function Analyzer-100 (PFA-100) closure times (CTs) by collagen/adenosine 5'-diphosphate (ADP) (C/ADP CT) cartridge and the VerifyNow P2Y12 Assay (VerifyNow) with light transmission aggregation (LTA) induced by 2 and 10 micromol L(-1) ADP in 1267 CAD patients on dual antiplatelet therapy who underwent percutaneous coronary intervention. We also performed the vasodilator-stimulated phosphoprotein (VASP) phosphorylation assay by cytofluorimetric analysis in a subgroup of 115 patients.
Results:
Cut-off values for identifying RPR were: > or = 54% and > or = 66% for LTA induced by 2 and 10 micromol L(-1) ADP respectively, and > or = 264 P2Y12 Reaction Units (PRU) for VerifyNow. The cut-off for PFA-100 C/ADP CT was > or = 68 s. RPR was detected in 25.1% of patients by 2 mumol L(-1) ADP-induced LTA (ADP-LTA), in 23.2% by 10 micromol L(-1) ADP-LTA, in 24.4% by PFA-100, and in 24.7% by VerifyNow. PFA-100 results did not parallel those obtained with LTA. VerifyNow showed a significant correlation (rho = 0.62, P < 0.001) and significant agreement (k = 0.34, P < 0.001) with LTA induced by 2 micromol L(-1) ADP. The correlation was similar but the agreement was better between VerifyNow and 10 micromol L(-1) ADP-LTA (rho = 0.64, P < 0.0001; k = 0.43, P < 0.001). Significant relationships were found between VASP platelet reactivity index and both ADP-LTA and VerifyNow. PFA-100 C/ADP CT did not significantly correlate with any of the other assays.
Conclusions:
Our results show a significant correlation between LTA and VerifyNow but not the PFA-100 C/ADP assay. Clinical validation studies for POC systems are necessary.
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