Atrial functional mitral regurgitation: The concept has evolved, but inconsistencies still remain.

In our commentary we elucidated the fact that functional mitral regurgitation (FMR) is divided into two morphological subtypes: annular dilation with normal leaflet motion (Carpentier type I) and restricted systolic motion with left ventricular remodeling or dysfunction (Carpentier type IIIb). However, these phenotypes show some degree of overlap and there are currently no distinctive diagnostic cut-off values, therefore they may represent a continuum of the same disease. Moreover, correct left chambers quantification is critical for differentiating between atrial FMR and ventricular FMR. Three-dimensional echocardiography can quantify better leaflet areas, lengths, and closing angles, as well as the coaptation index, by eliminating geometric assumptions and integrating tethering of all leaflet surface and annular area enlargement. Also, It is expected that the use of artificial intelligence solutions and the deployment of automated onboard software that requires no or limited human input will stimulate wider clinical use of three-dimensional echocardiography in left chambers quantification.