The PORTICO trial studies a new way to fix a heart valve problem called aortic stenosis. Aortic stenosis occurs when the heart valve doesn't open properly, making it hard for blood to flow. This trial uses a device called the Portico Transcatheter Heart Valve, which is inserted without open-heart surgery. The trial will include 750 patients who are at high risk for surgery. Half will receive the Portico device, and the other half will receive a different approved heart valve device. Researchers will check safety after 30 days and effectiveness after 1 year. Another group will test a new delivery system called FlexNav. All patients will have follow-up visits for 5 years to monitor their health.

• The study will last for 5 years with several follow-up visits.
• Participants are high-risk patients with severe heart valve issues.
• A new heart valve system is tested for safety and effectiveness.