The invention relates to a prosthesis (1) which includes an expandable tubular framework (2) with a mesh structure and a prosthetic valve (3) mounted on said framework. According to the invention: the ventricular portion (2v) of the framework (2) has a wide recess (6) on one side, extending lengthwise from the end of said ventricular portion (2v) which is opposite the annular portion (2i) until reaching the part of said ventricular portion (2v) next to the annular portion (2i), said recess (6) extending over a sector of the circumference of the prosthesis (1) of the order of 90 º to 140 ° the atrial portion (2a) gradually flares towards the outside of the prosthesis from said annular portion (2i) towards the end of said atrial portion opposite said annular portion, and includes anchoring points (5a) on the side of the annular portion (2i) and said ventricular portion (2v) has a substantially spherical or ovoid shape and includes anchoring points (5v) on the side of said annular portion (2i).
