No association between on-treatment platelet reactivity and bleeding events following percutaneous coronary intervention and antiplatelet therapy: A post hoc analysis

- We examined the associations between thienopyridines and bleeding events after PCI.
- PRU and VASP-PRI were not associated with bleeding in the acute or chronic phases.
- Bleeding was not increased in patients with low on-treatment platelet reactivity.

IntroductionFew studies have examined the relationship between the pharmacodynamics of antiplatelet drugs and the risk of clinically significant bleeding following percutaneous coronary intervention (PCI) for treating acute coronary syndrome (ACS). We examined the associations between the pharmacodynamics of prasugrel and clopidogrel and the incidence of bleeding events in the acute and chronic phases after PCI.Materials and methodsWe performed a post hoc analysis of the PRASFIT-ACS (PRASugrel compared with clopidogrel For Japanese patIenTs with ACS undergoing PCI) study of patients in whom platelet reactivity was determined as P2Y12 reaction units (PRU; VerifyNow® P2Y12 assay) or vasodilator-stimulated phosphoprotein-phosphorylation reactivity index (VASP-PRI). Japanese patients were randomized to prasugrel (loading/maintenance dose: 20/3.75 mg) or clopidogrel (300/75 mg), both in combination with aspirin, for 24-48 weeks. The bleeding outcome was a composite of major, minor, and clinically relevant bleeding.ResultsOverall, 66/685 (9.6%) and 65/678 (9.6%) of prasugrel- and clopidogrel-treated patients, respectively, experienced major, minor, or clinically relevant bleeding. PRU and VASP-PRI at 5-12 h or in steady state conditions (at 4 weeks) were not associated with the risk of bleeding in the acute (to day 3) or chronic (from day 4 to 14 days after treatment discontinuation) phases of treatment, respectively. Less than 9% of patients with low on-treatment platelet reactivity (defined as PRU < 85 or VASP-PRI < 16) experienced bleeding events.ConclusionNo direct association of the pharmacodynamics of prasugrel and clopidogrel with the risk of bleeding was observed in this cohort of Japanese ACS patients following PCI.