Another common etiology of aortic stenosis
is a congenital defect in the valve, because 1%-2%
of the population are born with a bicuspid aortic
valve.5,6 Inheritance has been found to play a role,
with an autosomal dominant pattern and a variable
penetrance. A bicuspid aortic valve that does not yet
show any signs of damage nevertheless tends to open
and close with abnormal folding and creasing, leading
to scarring and calcification.5
Although patients with
a bicuspid aortic valve are asymptomatic until late
in the disease process, severe, symptomatic AS with
or without aortic regurgitation (AR) may develop
in mid-life.6
In undeveloped countries, rheumatic
disease is a fairly common cause of AS, and it is
usually associated with concomitant AR.