This prospectively enrolled, pragmatic randomized trial aims to investigate whether very low dose edoxaban regimen (15 mg daily) achieves similar edoxaban concentrations as low dose edoxaban regimen (30 mg daily), while maintaining a comparable risk of clinical outcomes and reducing major bleeding in elderly patients with atrial fibrillation and a history of ischemic stroke or transient ischemic attack.

Edoxaban, a factor Xa inhibitor, is used to prevent stroke or systemic thromboembolism (SSE) in patients with atrial fibrillation (AF). In elderly patients, the post-hoc analysis of the Effective Anticoagulation with Factor Xa Next Generation in Atrial Fibrillation-Thrombolysis in Myocardial Infarction 48 (ENGAGE AF-TIMI 48) trial showed that a low-dose edoxaban regimen (LDER, 30 mg daily) reduced the risk of major bleeding compared to the standard-dose edoxaban regimen (SDER, 60 mg daily), without an offsetting increase in SSE risk. Furthermore, the Edoxaban Low-Dose for Elder Care Atrial Fibrillation Patients (ELDERCARE AF) trial demonstrated that a very-low-dose edoxaban regimen (VLDER, 15 mg daily) was more effective than placebo for elderly patients where standard anticoagulant intensity posed safety concerns. Although both LDER and VLDER appear suitable for the elderly population, data comparing these two regimens are lacking.

Specific purpose:

To investigate whether VLDER (15 mg daily) achieves similar edoxaban concentrations as LDER (30 mg daily), while maintaining a comparable risk of clinical outcomes and reducing major bleeding in elderly patients with AF and a history of ischemic stroke (IS) or transient ischemic attack (TIA) through a pragmatic randomized trial.

Study design:

The Very Low-Dose Edoxaban in Elderly Atrial Fibrillation Patients with a History of Stroke (LEAVE-Stroke) trial is a prospective, multicenter, randomized trial. Elderly patients aged ≥ 80 years with AF, a history of IS/TIA and concerns about the bleeding risk of standard anticoagulant intensity will be enrolled. Participants will be randomized to either the VLDER or LDER group.

Participant number: 120 patients (60 patients in each group). YEAR 1: Participant enrollment for the LEAVE-Stroke trial. YEAR 2: Continued participant enrollment, followed by a comparison of edoxaban concentration and clinical outcomes between two dose groups.

Study outcomes:

Primary outcome: The proportion of patients achieving edoxaban concentrations within the expected range from the ENGAGE-AF TIMI 48 trial (12-43 ng/mL at trough) at 1 month.

Secondary outcome: Major bleeding at 3 months, a composite of major bleeding, SSE or death at 3 months.

Significance: This pragmatic randomized trial will be the first to report real-world edoxaban concentrations in the VLDER group and to determine whether they are comparable to those in the LDER group. Furthermore, the study will provide insights into the short-term outcomes of VLDER in elderly patients with AF, a history of IS/TIA, and concerns about increased bleeding risk. These findings will not only inform edoxaban dosing strategies in clinical practice but also serve as a foundation for future large-scale, long-term studies to evaluate the feasibility and safety of using VLDER in this high-risk population.

Keywords: very low-dose edoxaban, elderly, drug concentration, major bleeding, atrial fibrillation

Inclusion Criteria:

• Age>=80 years
• Has been diagnosed atrial fibrillation
• Has history of ischemic stroke or transient ischemic attack
• Has any of the bleeding risk lists below
• bodyweight < 60 kg
• creatinine clearance < 50 mL/min
• history of major bleeding or gastrointestinal bleeding
• concurrent use of antiplatelet agents (such as aspirin, clopidogrel, ticagrelor, prasugrel, cilostazol), non-steroidal anti-inflammatory drugs, amiodarone, tacrolimus, cyclosporine, dronedarone.

Exclusion Criteria:

• Has ever used anticoagulants, defined as:
• warfarin therapy within 1 month before study enrollment.
• using heparin, low molecular weight heparin or direct oral anticoagulants within 7 days before study enrollment.
• allergy to edoxaban
• under regular dialysis, includes hemodialysis or peritoneal dialysis
• refuse to provide informed consent.