Correlation of high post-treatment platelet reactivity assessed by light transmittance aggregometry and the VerifyNow P2Y12 assay

Abstract

In vitro "high post-treatment platelet reactivity" (HPPR) measured with light transmittance aggregometry (LTA) and the VerifyNow P2Y(12) assay has been associated with an increased risk of ischemic events after percutaneous coronary intervention (PCI). However, there are many criteria for HPPR according to the methods used for assessment, and correlations among suggested criteria have not been evaluated. To this end, we enrolled 1,058 unselected patients undergoing PCI in real clinical practice, simultaneously assessed platelet measures with LTA (both 5 and 20 μmol/l ADP-induced) and the VerifyNow P2Y(12) assay, and based on previous studies, evaluated the following criteria for HPPR: 5 or 20 μmol/l ADP-induced maximal platelet reactivity (PR(max)) ≥50%; 5 μmol/l ADP-induced late PR (PR(late)) >14%; 20 μmol/l ADP-induced PR(max) ≥62%; and P2Y(12) reaction unit (PRU) ≥240. Receiver-operating characteristics (ROC) curve analysis demonstrated that PRU (cut-off = 241) distinguished between patients with and without 5 μmol/l ADP-induced PR(max) ≥50% (area under curve [AUC] 0.822, sensitivity 83.0%, specificity 66.0%, P < 0.001), and 20 μmol/l ADP-induced PR(max) ≥62% (AUC 0.840, sensitivity 80.7%, specificity 71.4%, P < 0.001), respectively. PRU ≥240 showed a moderate agreement with 5 μmol/l ADP-induced PR(max) ≥50% (κ = 0.438, concordant rate 71.6%, P < 0.001) and 20 μmol/l ADP-induced PR(max) ≥62% (κ = 0.505, concordant rate 75.1%, P < 0.001). Cut-offs matched for 20 μmol/l ADP-induced PR(max) ≥50% (PRU = 195) and 5 μmol/l ADP-induced PR(late) >14 (PRU = 194) also were similar. The presence of significant correlations between the suggested criteria for HPPR has practical implications on the possible use of the VerifyNow P2Y(12) assay for risk stratification in PCI-treated patients.

Effect of ampicillin on bleeding time in very low birth-weight neonates during the first week after birth

“…[1][2][3][4][5][9][10][11][12][13] Other tests of platelet function are less applicable for VLBW neonates, principally because of a larger volume of blood needed. These include light transmittance platelet aggregometry, 14 whole-blood aggregometry, 15 multiple electrode aggregometry, 16 thromboelastography 17 and vasodilator-stimulated phosphoprotein phosphorylation. 18 Ampicillin impairs platelet function and prolongs the bleeding time, 5-8 but it does not do so immediately as occurs with clopidogrel (plavix) or aspirin.…”

The platelet P2Y12 receptor for adenosine diphosphate: congenital and drug-induced defects

“…Several recent studies demonstrated that the agreement among different laboratory tests to identify poor responders is rather low and that assessment of platelet response to clopidogrel is highly test-specific. [71][72][73][74][75][76] Recent studies showed that the search for loss of function mutations of CYP is not very accurate in predicting the response to clopidogrel. 77,78 In addition, preliminary experiments that evaluated the effects of increasing the dose of clopidogrel in resistant patients gave results that are incompletely satisfactory because many patients remained "resistant" to clopidogrel, even after repeated administrations of high doses of the drug.…”

Effect of CYP2C19*2 and *3 Loss-of-Function Alleles on Platelet Reactivity and Adverse Clinical Events in East Asian Acute Myocardial Infarction Survivors Treated With Clopidogrel and Aspirin

“…22 Platelet-rich plasma was obtained after centrifugation of the blood at 120 g for 10 minutes. The remaining blood was further centrifuged at 1200g for 10 minutes to collect platelet-poor plasma.…”

“…22 Blood was drawn into a Greiner Bio-One 3.2% citrate Vacuette tube (Greiner Bio-One, Kremsmünster, Austria). The assay channel contains fibrinogen-coated polystyrene beads, 20 mol/L ADP, and 22 nmol/L PGE 1 .…”