Functional or secondary mitral regurgitation (MR) arises due to an imbalance between mitral leaflet tethering and closure forces, resulting in the absence of leaflet coaptation. Functional MR (FMR) is now subdivided into ventricular functional MR (V-FMR), which occurs as a consequence of left ventricular dysfunction and remodeling (seen in both ischemic and nonischemic conditions), and atrial functional MR (A-FMR), which is primarily related to mitral annular (MA) enlargement due to left atrial (LA) dilation, commonly associated with chronic atrial fibrillation (AF) and/or heart failure with preserved ejection fraction.In this issue of Echocardiography, Chang et al. [1] retrospectively evaluated mitral valve (MV) remodeling in non-valvular AF patients, comparing those with paroxysmal AF, persistent AF, and absence of AF patients at their institution (Guangxi Medical University, Nanning, China). Specifically, the study analyzed LA and ventricular size and function, the MV anatomy, and the MR severity across three groups: 30 patients with no AF history (referred for Patent Foramen Ovale), 82 patients with paroxysmal AF, and 66 patients with persistent AF.