Edoxaban trough concentration and PT predict major bleeding in very old AF patients

BACKGROUND: Edoxaban is a direct oral anticoagulant used for stroke prevention in patients with atrial fibrillation (AF) and treatment of venous thromboembolism. We examined the relationship between trough edoxaban concentrations (E-trough) and prothrombin time (PT) and major bleeding in very old Japanese patients with atrial fibrillation and high bleeding risk. METHODS: In this post hoc analysis of the multicenter, randomized, double-blind, placebo-controlled ELDERCARE-AF (Study of DU-176b Aged 80 Years or Older) trial, patients were randomly assigned 1:1 to edoxaban 15 mg or placebo once daily. After 8 weeks of treatment, E-trough was determined and the incidence of major bleeding examined in each quartile. The incidence of major bleeding by PT was also examined. RESULTS: Data were obtained from 427 patients. E-trough (ng/mL) was ≤9.24 in the first quartile (107 patients), >9.24 to ≤13.6 in the second (111 patients), >13.6 to ≤21.6 in the third (103 patients), and >21.6 in the fourth (106 patients). Older age, lower body weight, lower creatinine clearance, and the presence of congestive heart failure were independent predictors of higher E-trough. Higher E-trough was associated with greater incidence of major bleeding (0.8%, 1.9%, 3.4%, and 4.7%/year, respectively, =0.0408). There was a significant positive correlation between E-trough and PT (=0.426, <0.0001). Significantly more major bleeding events occurred in the longer (>13 seconds) versus shorter (≤13 seconds) PT subgroups (4.61% versus 0.98%/year, =0.0060). CONCLUSIONS: Several factors were associated with higher E-trough and increased risk of major bleeding events. PT >13 seconds may be a useful predictor of the development of major bleeding. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02801669.