High and low on-treatment platelet reactivity to P2Y inhibitors in a contemporary cohort of acute coronary syndrome patients undergoing percutaneous coronary intervention.

INTRODUCTION

There is compelling evidence supporting the association between high on-treatment platelet reactivity (HPR) and low on-treatment platelet reactivity (LPR) to clopidogrel with atherothrombotic and bleeding events, respectively. However, it is uncertain if current cutoff values should be used in prasugrel- or ticagrelor-treated subjects. The objective of this analysis was to evaluate the pharmacodynamic (PD) efficacy of P2Y antagonists in a contemporary real-world population.

MATERIALS AND METHODS

This PD study included 988 patients with acute coronary syndromes (ACS) undergoing percutaneous coronary intervention (PCI) and receiving dual therapy with aspirin and a P2Y inhibitor (clopidogrel, prasugrel or ticagrelor). Platelet function was assessed at day 1 and day 30 post-PCI by VerifyNow P2Y12 assay, multiple electrode aggregometry and vasodilator-stimulated phosphoprotein (VASP) assay.

RESULTS

Clopidogrel-treated patients (n = 324) had greater platelet reactivity than those receiving ticagrelor (n = 469) or prasugrel (n = 195) at both time points (p < 0.001 for all comparisons). No difference between ticagrelor and prasugrel was observed at day 1 with the VerifyNow P2Y12 assay (51.5 ± 2.8 vs. 42.7 ± 3.5 PRUs; p = 0.298), whereas ticagrelor achieved greater platelet inhibition at day 30 (48.1 ± 2.5 vs. 89.2 ± 4.2 PRUs; p < 0.001). Similar results were obtained with the VASP assay. Both prasugrel and ticagrelor had markedly lower HPR rates than clopidogrel and very high rates of LPR at both time points.

CONCLUSIONS

Prasugrel and ticagrelor displayed more potent and consistent PD effects than clopidogrel in ACS patients undergoing PCI, with a trend towards greater platelet inhibition with ticagrelor during the maintenance phase of therapy compared to prasugrel.