A circular band intended to be implanted in the heart to support a mitral valve annulus for the reconstruction and/or remodelling of an insufficient and/or stenotic mitral valve. It is typically mounted on a disposable holder assembly or preloaded in a disposable delivery system to enable it to maintain its shape and aid in its implantation with sutures or anchors. The device may be semi-rigid or flexible and may include metallic, polymeric, and/or textile materials; it is available in various sizes.