Platelet reactivity in patients receiving a maintenance dose of P2Y12-ADP receptor antagonists undergoing elective percutaneous coronary intervention

BACKGROUND

P2Y12-ADP receptor blockade during percutaneous coronary intervention (PCI) is critical to prevent thrombotic events. In patients under chronic P2Y12 blockers, the use of additional loading dose (LD) before an elective PCI is debated. We aimed to investigate the rate of high on-treatment platelet reactivity (HTPR) in patients undergoing elective PCI during chronic clopidogrel or ticagrelor therapy.

METHODS AND RESULTS

We performed a sub-group analysis of a randomized trial comparing ticagrelor and clopidogrel in acute coronary syndrome (ACS) patients undergoing PCI. Multi-vessel disease patients requiring a staged PCI one month after the ACS were included. The VASP (vasodilatatory phosphoprotein) index, which is a specific and reproducible platelet assay to measure P2Y12-ADP receptor activity, was used to assess the biological efficacy of the maintenance dose (MD) of ticagrelor and clopidogrel before PCI. Forty-one patients in each group of randomization required a staged PCI. They were similar regarding the baseline demographic, clinical and angiographic characteristics. The mean VASP index in the ticagrelor group was 20.7±8.8% compared to 51.8±17% in the clopidogrel group (p<0.001) before PCI. No patients had a VASP index ≥50% in the ticagrelor group compared to 56% in the clopidogrel group (p<0.001). Following PCI the rate of peri-procedural MI was higher in the clopidogrel group (p=0.02).

CONCLUSIONS

Unlike clopidogrel MD, ticagrelor MD achieves an optimal PR inhibition in all patients during a staged PCI.

Ticagrelor increases endothelial progenitor cell level compared to clopidogrel in acute coronary syndromes: A prospective randomized study

BACKGROUND

The clinical benefit of ticagrelor compared to clopidogrel in ACS patients suggested off-target property. Such pleiotropic effect could be mediated by circulating endothelial progenitor cells (EPC) which are critical for vascular healing. We aimed to investigate the impact of ticagrelor on EPC in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI).

METHODS

We prospectively randomized 106 ACS patients to ticagrelor or clopidogrel. Sub-populations of CD34+ circulating progenitor cells (PC) were analyzed by flow cytometry allowing one to determine the levels of CD34+ PC, CD34+CD45+ Hematopoietic PC, CD34+133+ immature PC and CD34+KDR+ EPC on admission and at 1 month. Changes in PC level were calculated as the difference between 1 month and baseline value.

RESULTS

The 2 groups were similar regarding baseline characteristics including PC numbers on admission. The 2 groups had similar change in overall CD34+ PC and hematopoietic CD34+45+ PC level (p=0.2). On the contrary, when considering CD34+133+ PC and CD34+KDR+ EPC, we observed that patients treated by ticagrelor had a significantly higher increase in levels of these PC subtypes compared to those treated by clopidogrel (0.23 (-0.33; 0.79) vs 0.00 (-0.5; 0.34); p=0.04 and 0.01 (-0.04; 0.05) vs -0.01 (-0.06; 0.03); p=0.02). Changes in the level of CD34+CD133+ PC correlated with platelet activity measured by the VASP index (r=-0.30; p=0.008). By contrast the increase in the level of CD34+KDR+ EPC in the ticagrelor group was independent of platelet activity.

CONCLUSIONS

Ticagrelor increases the number of EPC in ACS patients suggesting a benefit on endothelial regeneration that may participate in the pleiotropic property of the drug.