Rheumatic fever is an infection that can cause the aortic valve leaflets to stick together, which narrows the opening.

The most common cause of rheumatic fever is an untreated streptococcal infection (strep throat). With the widespread use of antibiotics to treat strep throat, rheumatic fever has been uncommon in the United States since the 1970s. However, 30 or 40 years ago rheumatic fever was the number one cause of aortic valve stenosis.

When rheumatic fever develops, it usually occurs in school-aged children. Rheumatic fever can cause inflammation in the brain, heart, joints, or skin. It takes 30 to 40 years for severe aortic valve stenosis to develop following a case of rheumatic fever.