Predicting impaired cardiopulmonary exercise capacity in patients with atrial fibrillation using a simple echocardiographic marker

Background Exercise intolerance is a common symptom associated with atrial fibrillation (AF). However, echocardiographic markers that can predict impaired exercise capacity are lacking. Objective To investigate the association between echocardiographic parameters and exercise capacity assessed via cardiopulmonary exercise testing (CPET) in patients with AF. Methods This single-center prospective study enrolled patients with AF who underwent echocardiography and CPET to evaluate exercise capacity at a tertiary center for AF management from 2020 to 2022. Patients with valvular heart disease, reduced left ventricular ejection fraction, or documented cardiomyopathy were excluded. Results Among the 188 patients, 134 (71.2%) exhibited impaired exercise capacity (peak oxygen consumption [VO2] ≤85%), including 4 (2.1%) having poor exercise capacity (peak VO2 <50%). Echocardiographic findings revealed that these patients had an enlarged left atrial (LA) size, smaller left ventricular end-diastolic diameter (LVEDD), and increased relative wall thickness, tricuspid regurgitation velocity, and LA/LVEDD and E/e′ ratios. Additionally, they exhibited lower peak systolic velocity of the mitral annulus and LA reservoir strain. In the multivariate regression model, LA/LVEDD remained the only significant echocardiographic parameter after adjusting for age, sex, and body mass index (P=0.020). This significance persisted even after incorporating heart rate reserve, N-terminal pro-B-type natriuretic peptide level, and beta-blocker use into the model. Conclusion In patients with AF, LA/LVEDD is strongly associated with exercise capacity. Further follow-up and validation are necessary to clarify its clinical implications in patient care.