The invention is a cardiac implant, and associated methods therefore, configured to repair and/or replace a native heart valve, and having a support frame configured to be reshaped into an expanded/changed form in order to receive and/or support an expandable prosthetic heart valve therein. The implant may be configured to have a generally rigid and/or expansion-resistant configuration when initially implanted to replace/repair a native valve (or other prosthetic heart valve), but to assume a generally non-rigid and/or expanded/expandable form when subjected to an outward force such as that provided by a dilation balloon. The implant may be configured to have a generally D-shaped configuration when initially implanted, but to assume a generally circular form when subjected to an outward force such as that provided by a dilation balloon.