Age-Dependent Anticoagulant Therapy for Atrial Fibrillation Patients with Intermediate Risk of Ischemic Stroke: A Nationwide Population-Based Study

Background ?Although older age is one of the most important risk factors for stroke in atrial fibrillation (AF), it is unclear whether an age threshold exists for which oral anticoagulants (OACs) are beneficial for intermediate-risk AF patients. We sought to investigate the age-dependency of OAC for ischemic stroke in intermediate-risk AF patients. Methods ?We enrolled 34,701 AF patients (males with a CHA ₂DS ₂-VASc score of 1 and females with a CHA ₂DS ₂-VASc score of 2) using the Korean National Health Insurance Service database. The clinical endpoint was the occurrence of ischemic stroke and a composite outcome (ischemic stroke + major bleeding + all-cause death). Results ?In AF patients aged ≥ 55 years, OAC therapy was associated with a lower risk of ischemic stroke compared with non-OAC treatment in males (55-59 years: hazard ratio [HR] 0.79, 95% confidence interval [CI] 0.61-0.98, p = 0.038, 60-64 years: HR 0.78, 95% CI 0.61-0.96, p = 0.029, and 65-74 years: HR 0.66, 95% CI 0.49-0.84, p = 0.011) and females (55-59 years: HR 0.76, 95% CI 0.58-0.96, p = 0.027, 60-64 years: HR 0.73, 95% CI 0.55-0.93, p = 0.017, and 65-74 years: HR 0.69, 95% CI 0.51-0.87, p = 0.013). OAC was associated with a lower risk for the composite outcome compared with non-OAC for male and female patients aged ≥ 55 years. Conclusion ?Age is an important determinant of ischemic stroke and composite outcome in intermediate-risk AF patients. The benefit of OAC therapy for these AF patients appears to have an age threshold (age ≥ 55 years).