An annuloplasty device is disclosed comprising first and second support rings being configured to be arranged as a coil in a first configuration around an axial direction, wherein the first and second support rings are configured to be arranged on opposite sides of native heart valve leaflets of a heart valve, a stiffening unit, wherein at least part of the first and second support rings comprises an interior channel configured to receive the stiffening unit, wherein insertion of the stiffening unit into the interior channel increases the stiffness of the first and/or second support rings. A method of repairing a defective heart valve is also disclosed.