Rheumatic heart disease is cardiac inflammation and scarring triggered by an autoimmune reaction to infection with group A streptococci. In the acute stage, this condition consists of pancarditis, involving inflammation of the myocardium, endocardium, and epicardium. Chronic disease is manifested by valvular fibrosis, resulting in stenosis and/or insufficiency.
Rheumatic fever is rare before age 5 years and after age 25 years; it is most frequently observed in children and adolescents. The highest incidence is observed in children aged 5-15 years and in underdeveloped or developing countries where antibiotics are not routinely dispensed for pharyngitis and where compliance is low.
The average annual incidence of acute rheumatic fever in children aged 5-15 years is 15.2 cases per 100,000 population in Fiji
compared with 3.4 cases per 100,000 population in New Zealand,
and it less then 1 case per 100,000 population in the United States. Although rheumatic fever was previously the most common cause of heart valve replacement or repair, this disease is currently relatively uncommon, trailing behind the incidence of aortic stenosis due to degenerative calcific disease, bicuspid aortic valve disease, and mitral valve prolapse.