A radially expandable and collapsible armature (9) for a prosthetic mitral valve comprises a composite annular element (14), including a first support ring (14a) and a self-securing ring (14b), which is radially expandable when subjected to an axial strength, and an anchoring cup-shaped frame (10), comprising a plurality of expandable meridian elements (10b) connected by a lower expandable arched elements (10c), in such a way that the latters have a radius (r) smaller than the radius (R) of the formers.
