Validation of a New ELISA-Based Vasodilator-Associated Stimulated Phosphoprotein Phosphorylation Assay to Assess Platelet Reactivity Index in a Chinese Population

Abstract

The level of platelet reactivity during P2Y12-adenosine diphosphate receptor antagonist is associated with ischemic and bleeding risks following percutaneous coronary intervention in acute coronary syndrome. Determining platelet reactivity inhibition may be valuable for confirming effective platelet inhibition for individual patients and identifying patients at risk of bleeding. The enzymelinked immunosorbent assay (ELISA)-based vasodilator-stimulated phosphoprotein (VASP) assay offers unique advantages over other methods and has not been used in the Chinese population. We enrolled 10 healthy volunteers and 54 patients with acute coronary syndrome. The volunteers received no treatment, and patients were administered a loading dose of clopidogrel or ticagrelor. The platelet reactivity index (PRI) was measured using flow cytometry (FC)-VASP and ELISA-VASP at baseline and 8-hour postloading dose. Blood samples of healthy volunteers and clopidogrel-or ticagrelor-treated patients were frozen and stored for 1, 2, and 4 weeks after initial activation. All frozen samples were tested using ELISA-VASP. The PRI assessed by FC-VASP and ELISA-VASP correlated well showing a high degree of consistency in identifying high or low on-treatment platelet reactivity. No significant time-dependent changes in PRI results were observed in frozen samples stored up to 4 weeks compared to nonfrozen samples. The PRI of ticagrelor-treated patients was lower than that of clopidogrel-treated patients. The ELISA-VASP effectively assesses the PRI, and results obtained from frozen specimens are unaffected by storage and shipment prior to assay. Ticagrelor was superior to clopidogrel in decreasing the PRI.

Head-to-Head Comparison of Consensus-Recommended Platelet Function Tests to Assess P2Y12 Inhibition—Insights for Multi-Center Trials

“…We found their results to be strongly correlated. This conclusion is in agreement with previous studies that also found the assays to be highly concordant [10][11][12]. Indeed, Ding et al reported a correlation coefficient of 0.89 between the two VASP assays in healthy volunteers, which is very close to our coefficient (0.87).…”

“…The 2010 Working Group on High On-Treatment Platelet Reactivity, the 2015 Working Group on Thrombosis of the European Society of Cardiology, and the 2019 Expert Consensus on Platelet Function and Genetic Testing for Guiding P2Y 12 Receptor Inhibitor Treatment each published position papers on platelet function testing in patients on P2Y 12 inhibitors. These papers suggested that platelet function could be tailored within a therapeutic window to balance ischemic versus bleeding complications [1][2][3].…”

The Role of Dual Antiplatelet in Stent-Assisted Coiling in Wide-Neck Aneurysm

“…Further differences between these tests should be based on their sensitivity and specificity in predicting atherothrombotic events after percutaneous coronary intervention (PCI), as well as their cost and labor intensity. 3,15,16 The VASP assay is the only specific test for P2Y12 inhibition and is not affected by the effect of ADP on the P2Y1 receptor. It is measured with the platelet reactivity index (PRI).…”

“…This assay has been standardized, but the disadvantage is that this method needs a few steps for the testing, which is timeconsuming and costly. 16 Several studies have predicted thrombotic events by investigating the cut-off PRI value. Bonello et al were the first to use the VASP assay to determine the correlation of HRPR with clopidogrel and clinical incidence.…”

“…15 However, in the expert clinical consensus document, they suggest genetic testing for patients at high risk of thrombotic complications (stent thrombosis, multivessel PCI procedures, and/or other risk factors associated with high platelet responsiveness) may be beneficial. 15,16,17…”