Background: Right atrial (RA) size and function are not well described in long-standing persistent AF (LSPAF) patients, nor their value as a predictor for the left atrial (LA) voltage-defined fibrosis. Methods: An evaluation was made as to whether echocardiography determined RA length, planimetered area, volume, emptying fraction, stroke volume, expansion index and calculated derivates among the LSPSAF population predict LA low voltage areas (LVA) acquired with high-density and high-resolution bipolar voltage mapping using the CARTO®3 system. Results: 142 patients aged 63 (58-67) years old, 117 males, were enrolled in our study. LVA were detected in 54% of the patients.Severe global LVA burden was present in 15% of the patients, whereas 30% of the patients presented a disseminated pattern of remodelling. We have shown that (1) the majority of the study population (76%) presented enlarged RA, however RA volumes were larger than LA volumes in the minority of cases (2) RA enlargement had a positive correlation with the presence of mild-to-moderate tricuspid regurgitation, left ventricular hypertrophy, LA enlargement, LA area and volume (3), none of the RA indices were associated with the prediction of absolute LVA or advanced LA fibrotic remodelling, although patients with severe LVA burden presented longer RA length and a larger area than comparing to patients with less advanced remodelling pattern. Conclusions: It was found that RA enlargement and decreased RA function, common in LSPSAF patients, do not translate to the presence of voltage-derived LA fibrotic remodelling