ACURATE IDE: Safety and Effectiveness Study of ACURATE Valve for Transcatheter Aortic Valve Replacement

Subjects will be enrolled at up to 85 centers in the United States, Canada, Europe, and Australia. There will be up to 2,820 subjects in ACURATE IDE. The ACURATE IDE study cohorts include the following. * Main Randomized Cohort: A prospective, multicenter, 1:1 randomized controlled trial (RCT; ACURATE versus a commercially available balloon-expandable SAPIEN 3™ Transcatheter Heart Valve or future iteration \[SAPIEN 3; Edwards Lifesciences LLC, Irvine, CA, USA\] or a commercially available self-expanding CoreValve® Transcatheter Aortic Valve Replacement System, CoreValve® Evolut™ R Recapturable TAVR System, EVOLUT™ PRO System, or future iteration \[CoreValve; Medtronic, Inc., Dublin, Ireland\]). There will be up to 1,500 subjects in the RCT. * Roll-In Cohort: A non-randomized roll-in phase with the test device. Centers that do not have implantation experience with the ACURATE neo™ Aortic Bioprosthesis (transfemoral delivery; Boston Scientific Corporation, Marlborough, MA, USA) will perform at least 2 roll-in cases before commencing treatment in the randomized cohort. Centers with prior experience with ACURATE are not required to do roll-in cases. Data from roll-in subjects will be summarized separately from the randomized cohort and will not be included in the primary endpoint analysis. * 4D CT Imaging Substudy: Selected centers with the ability to perform high quality 4D computer tomography (CT) scans will include subjects in a 4D CT Imaging Substudy to assess the prevalence of reduced leaflet mobility and hypoattenuated leaflet thickening (HALT) and the relationship, if any, to clinical events. Subjects will be randomized to test (ACURATE) and control device. * ACURATE Prime™ XL Nested Registry: A non-randomized, nested registry cohort of subjects who will receive the ACURATE Prime™ Transfemoral Aortic Valve System XL (ACURATE Prime XL Nested Registry). Participating centers will be a subset of United States centers that have enrolled subjects in ACURATE IDE. Data from subjects in this nested registry will be summarized separately from the randomized and roll-in cohorts. * ACURATE Extended Durability Study: An additional 1:1 randomized study (ACURATE versus a commercially available balloon-expandable SAPIEN 3™ Transcatheter Heart Valve or future iteration \[SAPIEN 3; Edwards Lifesciences LLC, Irvine, CA, USA\] or a commercially available self-expanding CoreValve® Transcatheter Aortic Valve Replacement System, CoreValve® Evolut™ R Recapturable TAVR System, EVOLUT™ PRO System, or future iteration \[CoreValve; Medtronic, Inc., Dublin, Ireland\]) including only subjects considered to be at low surgical risk. Subjects will receive ACURATE neo2 (S, M, or L valve sizes) or ACURATE Prime XL. Data from subjects in the Extended Durability Study will be summarized separately from other cohorts. * ACURATE Continued Access Study (CAS): An additional cohort of subjects receiving ACURATE neo2 (S, M, and L valve sizes) or ACURATE Prime XL. Data from subjects in the ACURATE CAS will be summarized separately from other cohorts and will be used to further assess performance and safety. Follow-up * Subjects implanted with a test device will be assessed at baseline, peri- and post-procedure, at discharge or 7 days post-procedure (whichever comes first), 30 days, 6 months, 1 year, and then annually for 5 years post-procedure. * Subjects implanted with a control device will be assessed at baseline, peri- and post-procedure, at discharge or 7 days post procedure (whichever comes first), 30 days, 6 months, and 1 year post procedure. Per protocol, no additional follow-up is required beyond this period, and standard of care practices will apply. * Some subjects may have completed additional annual follow-up visits based on requirements outlined in earlier versions of the protocol. * Subjects who are enrolled but not implanted with a test or control device at the time of the procedure will be followed for safety through 1 year.