The majority of people who have aortic valve stenosis are older than 65 and have developed the condition slowly, over many years.

Most young people and teens who have the condition developed it as a result of a defect at birth (congenital heart defect). The most common heart defect that causes aortic stenosis is a bicuspid aortic valve. This is the most common cause of aortic stenosis in people younger than 65. A normal (tricuspid) aortic valve has three flaps called leaflets; a bicuspid valve only has two leaflets.

Aortic valve stenosis is more common in men than in women.¹

Some people may develop aortic stenosis after having rheumatic fever as a child. It usually takes 30 to 40 years after a case of rheumatic fever for aortic stenosis to develop. Rheumatic fever has been rare in the United States since the 1970s.