Prospective observational study in elderly patients with non-valvular atrial fibrillation: Rationale and design of the All Nippon AF In the Elderly (ANAFIE) Registry

Background: Although anticoagulation effectively prevents stroke in patients with atrial fibrillation (AF), it has been underused in elderly AF patients for many reasons, mainly because of knowledge gaps regarding cardiovascular treatment of these populations with multiple comorbidities and poor prognosis. The objectives of the All Nippon AF In the Elderly (ANAFIE) Registry are to collect real-world information about the clinical status of patients with non-valvular AF (NVAF) aged ≥75 years, current status of anticoagulant therapy, and prognosis with/without anticoagulation to establish a database for this specific patient population that is increasing remarkably worldwide. Methods and design: The ANAFIE Registry is an observational, multicenter, prospective study of Japanese patients with NVAF aged ≥75 years that will include 30,000 patients and have the primary endpoint of composite of stroke and systemic embolism over a 2-year follow-up period. In parallel with the main study, seven sub-cohort studies will be conducted with assessments including coagulation-fibrinolysis markers, echocardiography, heart rate, hypertension, cognitive function, frailty, and medication adherence. Subgroup analyses will be performed, and stratified by renal function, HbA1c, and maximum number of drugs used. The study was started in October 2016, with a planned 2-year recruitment period. As of January 31, 2018, 33,213 patients were enrolled; the recruitment was therefore ended 8 months earlier than the original plan. Conclusions: The ANAFIE Registry will provide a valuable database for the clinical status, management, and outcomes of mortality, stroke, systemic embolism, and hemorrhagic events with/without anticoagulation in the increasing population of elderly NVAF patients, and will identify risk factors associated with these clinical events.