P2Y12 receptor inhibition with prasugrel and ticagrelor in STEMI patients after fibrinolytic therapy: Analysis from the SAMPA randomized trial

- Fibrinolytic agents may stimulate platelet hyperactivity.
- High platelet reactivity is related to occurrence of ischemic events.
- Clopidogrel, in pharmacoinvasive strategy, showed suboptimal platelet inhibition.
- Prasugrel and ticagrelor have a slow action peak after fibrinolysis.
- The pharmacodynamics of prasugrel and ticagrelor are similar after fibrinolysis.

BackgroundA pharmacodynamic comparison between ticagrelor and prasugrel after fibrinolytic therapy has not yet been performed.MethodsIn the single-center SAMPA trial, 50 consecutive STEMI patients previously treated with clopidogrel and undergoing a pharmacoinvasive strategy were randomized to either a ticagrelor (n = 25) 180 mg loading dose followed by 90 mg bid, or a prasugrel (n = 25) 60 mg loading dose followed by 10 mg/day, initiated after fibrinolytic therapy but before angiography. Platelet reactivity was assessed with the VerifyNow P2Y12 assay at 0, 2, 6, and 24 h after randomization.ResultsMean times from fibrinolysis to prasugrel or ticagrelor administration were 11.1 ± 6.9 and 13.3 ± 6.3 h, respectively (p = 0.24). The values of PRU decreased significantly from baseline to 2 h (all p < 0.001) and from 2 h to 6 h (all p < 0.001) in both groups. There was no difference in PRU values between 6 h and 24 h. The mean PRU values at 0, 2, 6, and 24 h were 234.9, 127.8, 45.4, and 48.0 in the prasugrel group and 233.1, 135.1, 67.7, and 56.9 in the ticagrelor group, respectively. PRU values did not significantly differ between groups at any time period of the study.ConclusionsIn patients with STEMI treated with fibrinolytic therapy, platelet inhibition after clopidogrel is suboptimal and can be further increased with more potent agents. Ticagrelor and prasugrel demonstrated a similar extent of P2Y12 receptor inhibition within 24 h, although maximal platelet inhibition after these potent agents was not achieved for 6 h.

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