Three-dimensional transoesophageal echocardiography is crucial for valid assessment of mitral valve leaflet morphology in severe mitral regurgitation prior to interventional repair.

Our results demonstrate the superiority of 3D-TOE over 2D-TOE for accurate MV assessment in MR, especially for the determination of the functional PML length. Erroneous MV leaflet assessment may result in inadequate therapy restriction if the MV is deemed not suitable for interventional repair.