Prospective, randomized, unblinded, multi-center investigational study with enrollment at up to 45 investigational sites. The study is designed to compare the study device (Direct Flow Medical Transcatheter Aortic Valve System) composite event rate to a blended commercial comparator (using approved Medtronic self-expanding bioprosthesis or Edwards balloon-expandable bioprosthesis) in high and extreme risk Subjects with severe symptomatic aortic stenosis. Subjects will be followed through the index procedure, hospital discharge, and at 30 days, 6 months and 1 year for the primary endpoint analysis. Thereafter, annual follow-up at 2 through 5 years will be conducted and analyzed separately.~The primary study endpoint is a composite of all-cause mortality, disabling stroke, or moderate or greater residual aortic regurgitation (based on core lab assessment) at 1 year. All primary endpoint events will be evaluated by a CEC using the definitions located in this protocol.~A sample size of 648 subjects (432 subjects in Direct Flow Medical Transcatheter Aortic Valve System cohort + 216 subjects in blended control cohort) will provide at least 85% power to test that the study device is non-inferior to the comparator with non-inferiority margin of 10%.~Subjects must meet the fundamental enrollment criteria of severe symptomatic, calcific aortic stenosis with quantifiable and documented source records.
Prospective, randomized, unblinded, multi-center investigational study with enrollment at up to 45 investigational sites. The study is designed to compare the study device (Direct Flow Medical Transcatheter Aortic Valve System) composite event rate to a blended commercial comparator (using approved Medtronic self-expanding bioprosthesis or Edwards balloon-expandable bioprosthesis) in high and extreme risk Subjects with severe symptomatic aortic stenosis. Subjects will be followed through the index procedure, hospital discharge, and at 30 days, 6 months and 1 year for the primary endpoint analysis. Thereafter, annual follow-up at 2 through 5 years will be conducted and analyzed separately.