Pharmacodynamic comparison of ticagrelor monotherapy versus ticagrelor and aspirin in patients after percutaneous coronary intervention: The template (ticagrelor monotherapy and platelet reactivity) randomized controlled trial

Abstract

BACKGROUND: To assess differences in platelet inhibition during ticagrelor monotherapy (TIC) or dual therapy with ticagrelor and aspirin (TIC+ASP) in patients after percutaneous coronary intervention using a comprehensive panel of functional tests. METHODS AND RESULTS: In a single-center parallel group, open label, randomized controlled trial, 110 participants were randomized to receive either TIC (n=55) or TIC+ASP (n=55) for 4 weeks. The primary outcome was the platelet aggregation response with 10 μmol/L thrombin receptor activation peptide-6 (TRAP-6). The secondary outcomes were platelet aggregation responses and binding of surface activation markers with a panel of other activators. The mean percentage aggregation for 10 μmol/L TRAP-6 was similar for the TIC and TIC+ASP groups (mean difference+4.29; 95% CI, −0.87 to +9.46). Aggregation was higher in the TIC group compared with the TIC+ASP group with 1 μg/mL (+6.47; +2.04 to +10.90) and 0.5 μg/mL (+14.00; +7.63 to +20.39) collagen related peptide. Aggregation responses with 5 μmol/L TRAP-6, 5 μmol/L or 2.5 μmol/L thrombox-ane A2 receptor agonist and surface activation marker binding with 5 μmol/L TRAP-6 or 0.5 μg/mL collagen related peptide were the same between the treatment groups. CONCLUSIONS: Patients with PCI show similar levels of inhibition of most platelet activation pathways with TIC compared with dual therapy with TIC + ASP. However, the greater aggregation response with collagen related peptide during TIC indicates incomplete inhibition of glycoprotein VI (collagen) receptor-mediated platelet activation. This difference in pharmacodynamic response to anti-platelet medication may contribute to the lower bleeding rates observed with TIC compared with dual anti-platelet therapy in recent clinical trials. REGISTRATION INFORMATION: URL: https://www.isrctn.com; Unique Identifier ISRCTN84335288.