47Characteristics and outcomes of atrial fibrillation in patients without conventional risk factors: A RE-LY AF registry analysis

Abstract

Background: Lone atrial fibrillation (AF) lacks a widely accepted definition, and data on prevalence, risk factors, and prognosis outside of North America and Western Europe are sparse. Purpose: To study prevalence, characteristics, and outcomes in patients with lone AF from multiple regions of the world included in the RE-LY AF registry. Methods: The RE-LY AF registry prospectively enrolled 15400 patients, between December 2007 and October 2011, who presented to an emergency department with AF from 164 sites in 47 countries. We identified patients with classically-defined lone AF: age<60 years, without hypertension, coronary artery disease, heart failure, left ventricular hypertrophy, congenital heart disease, pulmonary disease, valve disease, hyperthyroidism, or recent cardiac surgery. All patients with lone AF as secondary diagnosis were manually screened to additionally exclude those with triggered AF (e.g. pericarditis, myocarditis). Results: Classically-defined lone AF was present in 796 patients (5%). In 779 (98%) patients additional risk factors were present, including borderline hypertension (130-140/80-90 mmHg 47%), kidney disease (eGFR<60 ml/min 57%), obesity (BMI>30; 19%), diabetes (5%), excessive alcohol intake (>14 units/week 4%), smoking (25%), and sleep apnea (2%). “Truly lone AF”, excluding these additional risk factors was extremely rare (17 patients [0.1%]). In North America/Western Europe obesity was common (30%), while excessive alcohol was in Africa (22%), and diabetes in the Middle East (11%). During one year follow-up, patients returned to the emergency department 1.261.3 times. Hospitalization for AF was required in 141 (18%) patients, 7 (0.9%) patients were hospitalized for heart failure, of which 3 (8%) in Africa. A total of 13 patients died (1.6%), 5 (0.6%) suffered a stroke, and 3 patients (0.4%) experienced major bleeding without differences between world regions. Conclusions: Classically-defined lone AF is uncommon among patients presenting to the emergency department. It is typically associated with additional risk factors that vary between regions. True lone AF is very rare. During 1 year follow-up lone AF poses a short-term risk of stroke and death, but a high rate of recurrent AF hospitalizations.