Rheumatic heart disease starts as a sore throat from a bacterium called Streptococcus pyogenes (group A streptococcus) which can pass easily from person to person in the same way as other upper respiratory tract infections. Strep infections are most common in childhood. In some people, repeated strep infections cause the immune system to react against the tissues of the body including inflaming and scarring the heart valves. This is what is referred to as rheumatic fever. Rheumatic heart disease results then from the inflammation and scarring of heart valves caused by rheumatic fever.
Rheumatic fever mostly affects children and adolescents in low- and middle-income countries, especially where poverty is widespread and access to health services is limited. People who live in overcrowded and poor conditions are at greatest risk of developing the disease. Where rheumatic fever and rheumatic heart disease are endemic, rheumatic heart disease is the principal heart disease seen in pregnant women, causing significant maternal and perinatal morbidity and mortality. Pregnant women with rheumatic heart disease are at risk of adverse outcomes, including heart arrythmias and heart failure due to increased blood volume putting more pressure on the heart valves.
