Mariëlle KloostermanJonas OldgrenDavid ConenJorge A. WongStuart J. ConnollyAlvaro AvezumSalim YusufMichael D. EzekowitzLars WallentinMarie Ntep-GwethPhilip JosephTyler W. BarrettSupachai TanosmsupWilliam F. McIntyreShun Fu LeeRatika ParkashGuy AmitAlex GrinvaldsIsabelle C. Van GelderJeff S. HealeyPopulation Health Research Institute, OntarioHopital Central de YaoundeVanderbilt University Medical CenterInstituto Dante Pazzanese de CardiologiaAkademiska SjukhusetMahidol UniversityLankenau Institute for Medical ResearchUniversity of Groningen, University Medical Center GroningenQEII Health Sciences Centre2020-08-252020-08-252020-06-01Europace. Vol.22, No.6 (2020), 870-87715322092109951292-s2.0-85086051549https://repository.li.mahidol.ac.th/handle/20.500.14594/58147© 2019 Published on behalf of the European Society of Cardiology. All rights reserved. The Author(s) 2020. For permissions, please email: journals.permissions@oup.com. Aims: Data on patient characteristics, prevalence, and outcomes of atrial fibrillation (AF) patients without traditional risk factors, often labelled 'lone AF', are sparse. Methods and results: The RE-LY AF registry included 15 400 individuals who presented to emergency departments with AF in 47 countries. This analysis focused on patients without traditional risk factors, including age ≥60 years, hypertension, coronary artery disease, heart failure, left ventricular hypertrophy, congenital heart disease, pulmonary disease, valve heart disease, hyperthyroidism, and prior cardiac surgery. Patients without traditional risk factors were compared with age- and region-matched controls with traditional risk factors (1:3 fashion). In 796 (5%) patients, no traditional risk factors were present. However, 98% (779/796) had less-established or borderline risk factors, including borderline hypertension (130-140/80-90 mmHg; 47%), chronic kidney disease (eGFR < 60 mL/min; 57%), obesity (body mass index > 30; 19%), diabetes (5%), excessive alcohol intake (>14 units/week; 4%), and smoking (25%). Compared with patients with traditional risk factors (n = 2388), patients without traditional risk factors were more often men (74% vs. 59%, P < 0.001) had paroxysmal AF (55% vs. 37%, P < 0.001) and less AF persistence after 1 year (21% vs. 49%, P < 0.001). Furthermore, 1-year stroke occurrence rate (0.6% vs. 2.0%, P = 0.013) and heart failure hospitalizations (0.9% vs. 12.5%, P < 0.001) were lower. However, risk of AF-related re-hospitalization was similar (18% vs. 21%, P = 0.09). Conclusion: Almost all patients without traditionally defined AF risk factors have less-established or borderline risk factors. These patients have a favourable 1-year prognosis, but risk of AF-related re-hospitalization remains high. Greater emphasis should be placed on recognition and management of less-established or borderline risk factors.Mahidol UniversityMedicineArticleSCOPUS10.1093/europace/euz360