Prasugrel Versus High Dose Clopidogrel to Overcome Early High on Clopidogrel Platelet Reactivity in Patients with ST Elevation Myocardial Infarction

Abstract

There is a paucity of data regarding the early effectiveness of the proposed 600 mg clopidogrel loading dose (LD) on platelet reactivity (PR) in ST elevation myocardial infarction (STEMI) patients. If high on-treatment platelet reactivity (HTPR) is present, prasugrel reloading and subsequent maintenance dose (MD), might offer faster and stronger platelet inhibition than high clopidogrel MD. In 93 STEMI patients treated by primary percutaneous coronary intervention we assessed PR using the VerifyNow P2Y12 platelet function test, 2 h following 600 mg LD of clopidogrel. All the 60 (64.5 %) patients exhibiting HTPR (defined as PR ≥ 235 P2Y12 reaction units), were randomized to 1 of 2 therapeutic strategies: reloading with prasugrel 60 mg/10 mg MD or high (150 mg) clopidogrel MD. The primary endpoint of PR at 24 h post randomization was lower in the prasugrel compared to the clopidogrel group (51.3, 25.7-77.0 versus 242.4, 215.8-268.9 P2Y12 reaction units, least square estimates, 95 % confidence intervals, p < 0.001). PR at 2 h and 5 days post randomization was lower in the prasugrel compared to the clopidogrel group (117.2, 70.9-163.4 and 101.6, 70.1-133.2 least square mean difference, 95 % confidence intervals, p < 0.001 for both). At all the time points of PR assessment, HTPR rates were lower in prasugrel than in clopidogrel group. HTPR is commonly observed early post 600 mg clopidogrel LD in STEMI patients. In this case, prasugrel 60 mg LD/10 mg MD provides faster and stronger platelet inhibition than a high clopidogrel MD regimen.