The goal of this study is to learn what effects the ABC Bicuspid Sizing Algorithm has on the clinical outcomes of patients with bicuspid aortic stenosis after having a transcatheter aortic valve replacement (TAVR) using the Sapien 3 valve. The main questions the study aims to answer are:

1. Does the ABC Bicuspid Sizing Algorithm increase the technical success at exit from the procedure room?
2. Does the ABC Bicuspid Sizing Algorithm increase the device success at 30 days after the procedure?

Participants already being evaluated for a TAVR as part of their regular medical care for bicuspid aortic stenosis will have their diagnostic images assessed using the ABC Bicuspid Sizing Algorithm to help determine their procedure type and valve size. They will have visits 30 days and one year after their procedure.

This is a multi-centre, international, prospective cohort study. Approximately 290 patients who are clinically eligible for transcatheter aortic valve replacement (TAVR) will be enrolled. Using information collected with the ABC Bicuspid Sizing Algorithm, physicians will make a treatment allocation between TAVR and surgical aortic valve replacement (SAVR), and determine valve sizing and deployment for TAVR-treated patients. Included in the algorithm use is the utilization of gated computed tomography evaluation or artificial intelligence-based simulation models in select cases with borderline feasibility. The findings of these additional assessments will be shared with the treating physicians for consideration in the final treatment decision.

Of the 290 patients, an estimated 230 will be recommended to have TAVR. Data will be collected from TAVR-treated patients at baseline, procedure, hospital discharge, and 30 days and one year after the procedure. Data will only be collected from SAVR-treated patients at baseline and procedure. Sites in Canada, Latin America, the Middle East, and Asia Pacific will participate.

Inclusion Criteria:

• Have bicuspid aortic valve disease
• Have severe aortic stenosis or mixed aortic stenosis and regurgitation requiring treatment
• Have no other condition requiring surgical intervention
• Have had a TAVR CT scan (retrospectively gated contrast enhanced acquisition) that is of diagnostic quality and includes multiphase reconstructions of the aortic root at the minimum available slice thickness (with at least three systolic and one diastolic phases)
• Would be treated with a Sapien 3 valve if found to be anatomically suitable for TAVR
• Have a suitable access route for TAVR with a Sapien 3 valve

Exclusion Criteria:

• Are treated with TAVR using a device other than a Sapien 3 valve
• Are unable to be treated with TAVR due to intercurrent illness, clinical instability, or death on waitlist after being accepted for TAVR

Patients referred to the TAVR program at select hospitals