A single arm, prospective multicenter non-randomized confirmatory clinical trial evaluating the Edwards SAPIEN XT™ transcatheter heart valve (model 9300TFX; "study valve"), its transfemoral delivery system, and crimper accessories. The trial includes a premarket confirmatory cohort to evaluate the system performance as well as a Post Market Clinical Follow-up phase involving expanded enrollment and long-term follow-up of all patients to evaluate valve performance out to 5 years.