Clinical outcomes, edoxaban concentration, and anti-factor Xa activity of Asian patients with atrial fibrillation compared with non-Asians in the ENGAGE AF-TIMI 48 trial

AIMS: Prior studies suggested that the risks of ischaemic stroke and bleeding in patients of Asian race with atrial fibrillation (AF) may be higher than that of non-Asians. In the analysis of ENGAGE AF-TIMI 48 trial, we compared clinical outcomes, edoxaban concentration, and anti-factor Xa (anti-FXa) activity, between Asian and non-Asian races. METHODS AND RESULTS: There were 2909 patients of Asian race and 18 195 non-Asian race in the ENGAGE AF-TIMI 48 trial. The risks of thromboembolism and bleeding events were compared for Asians and non-Asians treated with warfarin. The trough levels of edoxaban concentration and anti-FXa activity were also compared and correlated with the efficacy and safety of edoxaban vs. warfarin. Compared to non-Asian patients, the Asian population was on average 2 years younger and 20 kg lighter. In the warfarin group, the adjusted risk of ischaemic stroke did not differ significantly for patients of Asian and non-Asian race [adjusted hazard ratio (aHR) = 1.12, P = 0.56). Asians treated with warfarin had a higher-adjusted risk of intracranial haemorrhage (ICH: aHR 1.71, P = 0.03) compared with non-Asians. The trough edoxaban concentration and anti-FXa activity were 20-25% lower for Asians compared with non-Asians. Compared to warfarin, higher dose edoxaban significantly reduced ICH while preserving the efficacy of stroke prevention in both Asians and non-Asians. Two of three net clinical outcomes appeared to be more favourably reduced with edoxaban in Asians compared with non-Asians (Pint = 0.063 for primary, 0.037 for secondary, and 0.032 for third net clinical outcomes, respectively). CONCLUSION: Compared to warfarin, higher dose edoxaban preserved the efficacy for stroke prevention and was associated with a favourable safety profile for Asians, which may be due to the lower trough edoxaban concentration and anti-FXa activity achieved in patients of Asian race.