Evaluation of the Portico™ NG (Next Generation) Transcatheter Aortic Valve in High and Extreme Risk Patients With Symptomatic Severe Aortic Stenosis

The Portico NG Approval study will be conducted as a prospective, multi-center, international, single-arm investigational study. Up to 399 (includes up to 20 roll-ins) high or extreme risk patients with symptomatic, severe native aortic stenosis who are determined by an independent subject selection committee to meet eligibility criteria for Navitor Transcatheter Aortic Heart Valve implantation will undergo Navitor Valve implantation via a transfemoral or alternative access approach according to the site's anesthesia protocol for TAVR (transcatheter aortic valve replacement) procedure. Subjects participating in the clinical study will be followed for a total of 12 months with data collected at screening, baseline, procedure, prior to hospital discharge, and follow-up at 30 days, 12 months and annually at 2, 3, 4 and 5 years. This study will also include a product size extension, Navitor Titan™ valve, which includes up to 90 subjects (Titan cohort) who will undergo an implant attempt with the Navitor Titan valve. Subjects enrolled in the Titan cohort will undergo the same screening, baseline, procedure and follow-up assessments as the Portico NG cohort.