Clinical characteristics of atrial fibrillation patients with anemia: from the Fushimi AF registry

Purpose: Atrial fibrillation (AF) is a common arrhythmic disorder among the elderly, and is increasing significantly as the population ages (reportedly 0.6% of total population in Japan). Anemia is often observed in patients with AF, but clinical characteristics of those patients have not been well described. Methods: The Fushimi AF Registry, a community-based prospective survey, was designed to enroll all of the AF patients living in Fushimi-ku, Kyoto, Japan. Fushimi-ku is densely populated with a total population of 283,000, and is assumed to represent a typical urban community in Japan. At present, we have enrolled 3,378 Japanese AF patients (1.2% of total population) from March 2011 to December 2012. We defined anemia as reduced hemoglobin level (<11 g/dl), and investigated the clinical background of AF patients with anemia. Results: Among 3,141 patients in the Registry whose hematological values were available, 547 patients (17.4%) had anemia. AF patients with anemia were older than those without anemia (79.6±10.3 vs. 73.4±10.5 years of age; p<0.001). They were more likely to have various co-morbidities; heart failure (43.1% vs. 25.8%; p<0.001), coronary artery disease (19.5% vs. 14.8%; p=0.006), peripheral artery disease (6.2% vs. 4.2%; p=0.04), chronic kidney disease (52.5% vs. 22.3%; p<0.001), and history of major bleeding (4.2% vs. 1.5%; p<0.001). There was no significant difference in the prevalence of hypertension or diabetes between anemic and non-anemic AF patients (62.2% vs. 62.3%; p=0.95, 25.3% vs. 24.0%; p=0.54, respectively) Anemic AF patients showed greater CHADS2 score and CHA2DS2-VASc score (2.58±1.36 vs. 2.05±1.33; p<0.001, 4.22±1.64 vs. 3.35±1.68; p<0.001, respectively), and higher prevalence of previous stroke (25.8% vs. 18.6%; p<0.001). Patients receiving the prescription of oral anticoagulants were less in anemic patients (44.4% vs. 52.4%; p<0.001), and the vast majority of them were warfarin (43.0% vs. 49.6%; p=0.005). In patients with anemia, the presence of chronic kidney disease (CKD) did not affect the prevalence of previous stroke (25.8% in anemic AF patients with CKD vs. 27.1% in anemic AF patients without CKD; p=0.67) or that of major bleeding (4.9% vs. 3.6%; p=0.35). Conclusion: The Fushimi AF registry represents the clinical profile of real-world Japanese AF patients. AF patients with anemia were associated with higher prevalence of stroke as well as bleeding, irrespective of the presence of CKD.