An annuloplasty device for treating a defective mitral valve having an annulus, comprising a removable and flexible elongate displacement unit for temporary insertion into a coronary sinus adjacent the valve, wherein the displacement unit has a delivery state for delivery into the CS, and an activated state to which the displacement unit is temporarily and reversibly transferable from said delivery state, the displacement unit comprises a proximal reversibly expandable portion, a distal anchoring portion being movable in relation to the proximal expandable portion in a longitudinal direction of the displacement unit to said activated state in which the shape of the annulus is modified to a modified shape, wherein the proximal expandable portion is reversibly foldable to an expanded state for positioning against a tissue wall at the entrance of the CS, and wherein the distal anchoring portion comprises an inflatable unit, wherein the proximal expandable portion comprises expandable bows extending in the longitudinal direction, wherein the expandable bows are connected to a sheath and are configured to be expanded in a radial direction, perpendicular to the longitudinal direction, by pushing a proximal portion of the sheath towards the distal anchoring portion, characterized in that the bows comprise elongated ribs formed in the sheath by elongated cuts in the sheath, extending in the longitudinal direction, whereby the bows are formed from the same material as the sheath, wherein, when the proximal expandable portion is folded to the expanded state, the bows extend with a curvature forming an apex positioned at a maximum expanded diameter of the proximal expandable portion, whereby each of the bows extend with two expanded sections (118, 118') towards the apex, wherein the two expanded sections comprises a proximal expanded section and a distal expanded section, the distal expanded section is configured to be arranged against said tissue wall at the entrance of the CS, wherein at least a portion of the distal expanded section extends in a first direction forming a first angle (v 1) with the radial direction, and at least a portion of the proximal expanded section extends in a second direction forming a second angle (v 2) with the radial direction, wherein the first angle is less than the second angle. a removable and flexible elongate displacement unit for temporary insertion into a coronary sinus adjacent the valve, wherein the displacement unit has a delivery state for delivery into the CS, and an activated state to which the displacement unit is temporarily and reversibly transferable from said delivery state, the displacement unit comprises a proximal reversibly expandable portion, a distal anchoring portion being movable in relation to the proximal expandable portion in a longitudinal direction of the displacement unit to said activated state in which the shape of the annulus is modified to a modified shape, wherein the proximal expandable portion is reversibly foldable to an expanded state for positioning against a tissue wall at the entrance of the CS, and wherein the distal anchoring portion comprises an inflatable unit, a proximal reversibly expandable portion, a distal anchoring portion being movable in relation to the proximal expandable portion in a longitudinal direction of the displacement unit to said activated state in which the shape of the annulus is modified to a modified shape, wherein the proximal expandable portion is reversibly foldable to an expanded state for positioning against a tissue wall at the entrance of the CS, and wherein the distal anchoring portion comprises an inflatable unit, wherein the proximal expandable portion comprises expandable bows extending in the longitudinal direction, wherein the expandable bows are connected to a sheath and are configured to be expanded in a radial direction, perpendicular to the longitudinal direction, by pushing a proximal portion of the sheath towards the distal anchoring portion, characterized in that the bows comprise elongated ribs formed in the sheath by elongated cuts in the sheath, extending in the longitudinal direction, whereby the bows are formed from the same material as the sheath, wherein, when the proximal expandable portion is folded to the expanded state, the bows extend with a curvature forming an apex positioned at a maximum expanded diameter of the proximal expandable portion, whereby each of the bows extend with two expanded sections (118, 118') towards the apex, wherein the two expanded sections comprises a proximal expanded section and a distal expanded section, the distal expanded section is configured to be arranged against said tissue wall at the entrance of the CS, wherein at least a portion of the distal expanded section extends in a first direction forming a first angle (v 1) with the radial direction, and at least a portion of the proximal expanded section extends in a second direction forming a second angle (v 2) with the radial direction, wherein the first angle is less than the second angle.