A tool for remodeling a tissue annulus includes an elongate handle and a reshaping element on a distal end of the handle. The reshaping element may be directable between a first configuration to facilitate direction through a tissue annulus, and a second curved configuration to remodel tissue adjacent the tissue annulus. The tool may be used for treating a tissue annulus within a patient's heart, e.g., by introducing the reshaping element through the tissue annulus, and manipulating the tool to reshape the tissue annulus substantially to a contour of the reshaping element. The reshaping element may support the tissue while a prosthesis is secured to the tissue annulus, or the reshaping element may itself be secured to the tissue annulus and released from the tool.