Shinya Suzuki1, Takeshi Yamashita2, Masaharu Akao3, Ken Okumura4. 1. Department of Cardiovascular Medicine, The Cardiovascular Institute, 3-2-19 Nishiazabu, Minato-ku, Tokyo, 106-0031, Japan. sinsuz-tky@umin.net. 2. Department of Cardiovascular Medicine, The Cardiovascular Institute, 3-2-19 Nishiazabu, Minato-ku, Tokyo, 106-0031, Japan. 3. Department of Cardiology, National Hospital Organization Kyoto Medical Center, Kyoto, Japan. 4. Division of Cardiology, Saiseikai Kumamoto Hospital, Kumamoto, Japan.
Abstract
PURPOSE: To investigate the distribution of plasma apixaban levels and their relationships with clinical outcomes in elderly patients with atrial fibrillation (AF). METHOD: The J-ELD AF Registry is a multicenter prospective observational study of Japanese non-valvular AF patients aged ≥75 years taking an on-label dose of apixaban (3015 patients from 110 institutions). Among them, plasma apixaban levels at trough were estimated by anti-Xa assay (Api-AXA) in 943 patients. Patients with standard (5 mg bid; n = 431) and reduced (2.5 mg bid; n = 512) dose were further divided into two groups with low and high Api-AXA levels (boundary: median value). RESULTS: The incidence rates (per 100 person-years) of events in the low- and high-Api-AXA groups were as follows: 1.48 and 1.99 (log-rank test, P = 0.695) for stroke or systemic embolism, 0.98 and 1.49 (P = 0.652) for bleeding requiring hospitalization, and 0.49 and 0.99 (P = 0.565) for total deaths in patients with standard dose, versus 0.84 and 1.68 (P = 0.414), 0.42 and 4.64 (P = 0.004), and 2.52 and 6.65 (P = 0.035) in patients with a reduced dose, respectively. In multivariate Cox regression analysis among patients with a reduced dose, a high Api-AXA level was independently associated with bleeding requiring hospitalization (HR 12.12, 95% CI: 1.56-94.22) and nonsignificantly with total deaths. CONCLUSIONS: A high trough apixaban level in patients indicated for standard dose was not associated with adverse events, while a high apixaban level in patients indicated for a reduced dose was associated with bleeding requiring hospitalization.
PURPOSE: To investigate the distribution of plasma apixaban levels and their relationships with clinical outcomes in elderly patients with atrial fibrillation (AF). METHOD: The J-ELD AF Registry is a multicenter prospective observational study of Japanese non-valvular AFpatients aged ≥75 years taking an on-label dose of apixaban (3015 patients from 110 institutions). Among them, plasma apixaban levels at trough were estimated by anti-Xa assay (Api-AXA) in 943 patients. Patients with standard (5 mg bid; n = 431) and reduced (2.5 mg bid; n = 512) dose were further divided into two groups with low and high Api-AXA levels (boundary: median value). RESULTS: The incidence rates (per 100 person-years) of events in the low- and high-Api-AXA groups were as follows: 1.48 and 1.99 (log-rank test, P = 0.695) for stroke or systemic embolism, 0.98 and 1.49 (P = 0.652) for bleeding requiring hospitalization, and 0.49 and 0.99 (P = 0.565) for total deaths in patients with standard dose, versus 0.84 and 1.68 (P = 0.414), 0.42 and 4.64 (P = 0.004), and 2.52 and 6.65 (P = 0.035) in patients with a reduced dose, respectively. In multivariate Cox regression analysis among patients with a reduced dose, a high Api-AXA level was independently associated with bleeding requiring hospitalization (HR 12.12, 95% CI: 1.56-94.22) and nonsignificantly with total deaths. CONCLUSIONS: A high trough apixaban level in patients indicated for standard dose was not associated with adverse events, while a high apixaban level in patients indicated for a reduced dose was associated with bleeding requiring hospitalization.