An implantable prosthetic valve assembly having a support stent, or frame, having circumferential struts with multiple bends forming obtuse angles when the valve assembly is expanded to its functional size. The frame can be manufactured with one or more of the circumferential struts in a partially collapsed state and a flexible valve member can be mounted to the partially collapsed frame. The partially collapsed struts can be formed with multiple bends having angles selected to facilitate crimping of the frame to a profile suitable for percutaneous delivery. When the frame is expanded, the bends can expand to form obtuse angles, thereby enhancing the rigidity of the frame to better resist closing forces exerted on the valve assembly.