A cardiac stent assembly featuring support flaps for a heart valve replacement procedure, while being able to place a mechanical or biological valve in an adapter fixed on the inner part of a stent body of the stent assembly. The stent assembly can be placed within heart valves sustained on an annular or ovoid mechanical support ring. For the positioning procedure of the stent assembly in the valve, an application device can be used wherein the stent body is inside the application device so that is possible to assemble and keep the entire stent assembly ready for use.