ADP-induced platelet aggregation in patients with acute coronary syndrome treated with prasugrel or ticagrelor. Results of the ISAR REACT 5 platelet aggregation substudy

Abstract Introduction The recently published randomized multicenter open label ISAR REACT 5 trial showed that prasugrel was superior to ticagrelor with respect to the composite primary end point of death, myocardial infarction, or stroke at one year after randomization in patients with acute coronary syndrome with planned invasive evaluation. The reasons for this finding are speculative. Purpose The aim of this prespecified platelet aggregation substudy was to assess platelet aggregation induced by adenosine-diphosphate (ADP) in patients who received prasugrel or ticagrelor treatment and underwent PCI. Methods We assessed all patients who underwent PCI and who had valid ADP-induced platelet aggregation values at hospital admission and at 2–24 hours after administration of prasugrel or ticagrelor loading dose followed by maintenance dose. ADP-induced platelet aggregation values were measured using the Mulitplate Analyzer®. Patients were recruited in the German Heart Center, Munich, Germany or in Klinikum rechts der Isar, Munich, Germany, Technical University of Munich. Results A total of 608 patients were analyzed. Patients in the prasugrel group were slightly but significantly older than patients in the ticagrelor group (66,5 years versus 64,6 years, P=0,048). The remaining baseline characteristics did not significantly differ between the two treatment groups. ADP-induced platelet aggregation (median [IQR]) at baseline did not differ between prasgurel- and ticagrelor treated patients (809 [556; 1057] AU x min versus 797 [534–1095] AU x min. At 2–24 hours after study drug administration ADP-induced platelet aggregation was significantly lower in patients who had received prasugrel in comparison to ticagrelor (105 [57–176] AU x min versus 138 [77–207] AU x min (Figure 1). Conclusion ADP-induced platelet aggregation was significantly lower in patients who received prasugrel in comparison to patients who received ticagrelor, which could have influenced patients' outcome in the ISAR-REACT 5 trial. Figure 1 Funding Acknowledgement Type of funding source: None