Introduction: Prasugrel and ticagrelor are recommended over clopidogrel in ST-segment-elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PPCI). Limited data exist on the comparative pharmacodynamic (PD) effects of these agents in PPCI.
Methods: We conducted a post-hoc analysis pooling data from two randomized PD studies investigating prasugrel and ticagrelor in PPCI. We included 16 patients receiving ticagrelor 180 mg and 24 patients receiving prasugrel 60 mg loading dose (LD). PD included P2Y12 reaction units (PRU) measured by VerifyNow and platelet reactivity index (PRI) measured by VASP assessed before and at 5 time points after LD (30 min, 1 h, 2 h, 4 h, 24 h). High platelet reactivity (HPR) was defined as PRU>208 and PRI>50%. Plasma levels of prasugrel active metabolite and ticagrelor were measured and time to reach maximal concentration (Tmax) was calculated.
Results: After adjusting for baseline platelet reactivity, ticagrelor was associated with lower PRU than prasugrel at 1 and 2 h post-LD (Figure, upper panel), whereas no differences were shown at other time points. VASP showed parallel findings, with numerically lower PRI at 1 and 2 h post-LD in ticagrelor-treated patients; however, at 24 h PRI was significantly lower with prasugrel compared with ticagrelor (Figure, bottom panel). Non-statistically significant lower HPR rates were observed with ticagrelor in the first 4 h post-LD. At 24 h, only 1 patient receiving ticagrelor had HPR defined by VASP, and no patient had HPR by PRU. Tmax, indicating absorption speed, was numerically lower for prasugrel than for ticagrelor (geometric mean: 2.7 h vs 3.8 h).
Conclusions: In patients undergoing PPCI, ticagrelor appears to provide greater platelet inhibition compared with prasugrel in the first hours post-LD. However, prasugrel is associated with faster absorption and better antiplatelet effect at 24 h. Larger studies are warranted to confirm these findings.