Table 1.

Causes of AS. Wide frequency range generally reflects the age group(s) assessed by individual studies as well as population subgroups studied [79, 115-117].

Etiology	Approximate frequency (%)	Associated features
Aging/calcific	50 - 70	Increased risk of coronary events.
Bicuspid aortic valve	6 - 40	Dilatation or dissection of the aorta, involving the aortic root, ascending aorta, or aortic arch.
Rheumatic	2 - 11	Mitral valve almost always affected as well
Unicuspid aortic valve	<1	Dilatation or dissection of the aorta, involving the aortic root, ascending aorta, or aortic arch.
Post-endocarditis	<1	Extra-cardiac embolic phenomena.