Elderly patients are hyperresponsive to potent P2Y12 inhibitors

Background: Aging has recently been associated with increased basal platelet activation and platelet hyperreactivity in response to adenosine diphosphate (ADP) but with decreased platelet response to thrombin receptor stimulation in individuals without antiplatelet therapy. Objectives: To investigate platelet response to agonist stimulation in elderly patients (≥70 years) on dual antiplatelet therapy with potent P2Y12 inhibitors. Methods: Platelet aggregation in response to arachidonic acid (AA), ADP, collagen, the protease-activated receptor-1 agonist SFLLRN, and the protease-activated receptor-4 agonist AYPGKF was assessed by multiple electrode aggregometry in 79 prasugrel- and 77 ticagrelor-treated patients 3 days after acute percutaneous coronary intervention. Results: In the overall study population (N = 156), patients aged ≥70 years (n = 33) had lower platelet aggregation in response to AA, ADP, and SFLLRN than younger patients (all P < .05). In prasugrel-treated patients (n = 79), those aged ≥70 years (n = 13) showed lower platelet aggregation in response to all agonists than younger patients (all P < .05). In contrast, in ticagrelor-treated patients (n = 77), those aged ≥70 years (n = 20) only had lower ADP-inducible platelet aggregation than younger patients (P = .03), whereas platelet aggregation in response to AA, collagen, SFLLRN, and AYPGKF was similar between elderly and younger patients (all P > .05). Among patients aged ≥70 years, prasugrel-treated patients showed lower platelet aggregation in response to AA, collagen, and AYPGKF than those receiving ticagrelor (all P < .05). Conclusion: Patients aged ≥70 years on potent P2Y12 inhibitors exhibit increased inhibition of ADP-inducible platelet aggregation. In addition, elderly patients on prasugrel show a lower response to AA, collagen, SFLLRN and AYPGKF than younger patients.