{Reference Type}: Case Reports {Title}: A Case of Transient Mitral Regurgitation: Not Everything Is Always What It Seems. {Author}: Arias-Godínez JA;Raymundo-Martínez GI;Esparza-Dueñas MER;Fritche-Salazar JF;Cobey FC;Pandian NG; {Journal}: J Cardiothorac Vasc Anesth {Volume}: 36 {Issue}: 6 {Year}: 06 2022 {Factor}: 2.894 {DOI}: 10.1053/j.jvca.2021.11.038 {Abstract}: Mitral regurgitation (MR) is a common form of valvular heart disease that is associated with significant morbidity and mortality. MR can be broadly classified into 2 different categories: primary and secondary MR. Primary MR usually is caused by leaflet abnormalities, whereas secondary MR is a chronic disease secondary to geometric distortion of both the annulus and subvalvular apparatus because of left ventricular remodeling. Without acute changes in loading conditions, myocardial blood flow, or rhythm disturbances, functional MR typically is not transient. In this E-Challenge, the authors show a transient and completely reversible acute and severe form of functional MR with the use of multimodal echocardiography.