Atrial Functional Mitral Regurgitation: Contemporary Mechanisms, Imaging, and Perioperative Implications for Cardiothoracic Anesthesiologists and Intensivists.

Secondary mitral regurgitation (MR) is associated with substantial cardiovascular morbidity and mortality. Traditionally, secondary MR has been understood primarily as a ventricular disorder caused by structural and functional abnormalities of the left ventricle. However, atrial functional mitral regurgitation (AFMR) is increasingly recognized as a distinct pathophysiological entity characterized by left atrial and mitral annular dilatation despite relatively preserved left ventricular geometry and systolic function. AFMR is commonly encountered in older patients, particularly those with chronic atrial fibrillation, heart failure with preserved ejection fraction, or both, and presents unique perioperative diagnostic and management challenges. Contemporary data further suggest that AFMR is not a single rigid phenotype, but rather a spectrum of atrial and annular remodeling with variable degrees of leaflet tethering and, in some patients, early ventricular overlap. Recent work has also shown marked variability among published AFMR definitions, with important consequences for prevalence, morphology, and prognosis. For the cardiothoracic anesthesiologist and intensivist, differentiating AFMR from classical ventriculogenic functional MR is essential because this distinction influences hemodynamic goals, volume management, and procedural planning. This review summarizes the mechanisms underlying AFMR, emphasizes the pivotal role of multimodality imaging in diagnosis, reviews current and emerging interventional strategies, and outlines practical perioperative considerations.