Additional Study Information: The study is to determine whether aortic valve replacement is helpful for patients who have moderate-severe, calcific, aortic stenosis (a narrowing of the aortic heart valve, where calcium has attached to the valve surface, resulting in obstructed blood flow) and do not have symptoms. Subjects will be randomly assigned, l to one of two groups: (1) Treatment Group: Doctor will use the SAPIEN 3 or SAPIEN 3 Ultra Transcatheter Heart Valve system to replace your valve. or (2) Clinical Surveillance Group: If assigned to this group, subject will not have their heart valve replaced. However, the doctor will continue to provide optimal medical therapy and will closely monitor how subject is doing (this is called Clinical Surveillance).