The invention refers to a device for treatment of mitral annulus dilatation without the need for cardiopulmonary bypass, comprising an elongate body (8) made of memory metal which has a memory of an original shape, the elongate body having such dimensions as to be insertable through the venous system and into the coronary sinus (5) by a catheter technique and having two states, in a first of which the elongate body has a shape that is adaptable to the shape of the coronary sinus, and to the second of which the elongate body is transferable from the said first state by returning toward the original shape and assuming a reduced radius of curvature, whereby the radius of curvature of the coronary sinus is reduced as well as the circumference of the mitral valve annulus, when the elongate body is positioned in the coronary sinus.
