Rheumatic heart disease is permanent damage to the heart valves caused by the body’s own immune system after one or more episodes of rheumatic fever. It begins with something as common as strep throat, and if the infection goes untreated or keeps recurring, the resulting inflammation can scar and stiffen the heart’s valves over time. The mitral valve, which controls blood flow between the left chambers of the heart, is affected in roughly 80% of cases, either alone or alongside other valves.
How Strep Throat Leads to Heart Damage
The chain of events starts with a Group A Streptococcus infection, the same bacterium behind strep throat. In most people, a course of antibiotics clears the infection without complications. But when strep throat goes untreated, the immune system mounts a strong response, and in some individuals, that response goes wrong through a process called molecular mimicry.
Proteins on the surface of the strep bacterium closely resemble proteins found in human heart tissue. The immune system produces antibodies to fight the infection, but those antibodies also mistakenly attack the heart’s own cells, particularly a structural protein in heart muscle called myosin and a protein called laminin that lines the surface of heart valves. This triggers inflammation along the inner lining of the valves. Once the valve surface is inflamed, immune cells called T cells move in and infiltrate the valve tissue, deepening the damage. Over repeated episodes of rheumatic fever, this cycle of inflammation and healing leaves the valves scarred, thickened, and stiff.
Which Heart Valves Are Affected
The mitral valve takes the brunt of the damage. In a study of patients with confirmed rheumatic heart disease, about 47% had isolated mitral valve involvement, while another 34% had damage to both the mitral and aortic valves. Only about 9% had isolated aortic valve disease. The tricuspid valve, on the right side of the heart, is occasionally involved but rarely on its own.
The damage takes two main forms. Valve regurgitation means the valve doesn’t close properly, allowing blood to leak backward. Valve stenosis means the valve becomes so stiff and narrowed that blood can’t flow through it efficiently. Many people end up with a combination of both. Isolated mitral regurgitation (a leaky mitral valve) was the single most common pattern in clinical studies, found in about 25% of patients, followed by pure mitral stenosis at around 14%.
Symptoms of Rheumatic Heart Disease
In its early stages, rheumatic heart disease often produces no symptoms at all. The valve damage accumulates silently, sometimes over years, before the heart struggles enough for a person to notice something is wrong.
As the disease progresses, symptoms reflect the heart’s declining ability to pump blood efficiently. These include shortness of breath during physical activity or even at rest, fatigue that doesn’t match your level of exertion, chest pain or discomfort, and swelling in the feet, hands, or abdomen. A heart murmur, an abnormal whooshing sound heard through a stethoscope, is one of the earliest clinical signs. In more advanced disease, the heart may develop irregular rhythms like atrial fibrillation, which feels like a rapid or fluttering heartbeat. Some people with severe mitral stenosis cough up blood, a sign that pressure is building up in the blood vessels of the lungs.
Who Is Most at Risk
Rheumatic heart disease is overwhelmingly a disease of poverty. It thrives wherever strep throat is common but access to basic healthcare is limited. The key risk factors are environmental and economic rather than genetic.
Overcrowded living conditions are one of the strongest predictors. Research in Uganda found that people living in overcrowded households (defined as more than eight people in a home) had 1.35 times the odds of developing rheumatic heart disease compared to those in less crowded homes. Cases lived in homes averaging about 80 square feet per person, while controls had roughly 120 square feet. Distance from a health center compounded the risk: for every additional kilometer a person lived from the nearest clinic, the effect of overcrowding on disease risk grew. Unemployment independently raised the odds by 1.7 times.
Children between ages 5 and 15 are the most vulnerable to rheumatic fever, the precursor condition. In high-income countries like the United States, Australia, and much of Western Europe, the disease has become rare thanks to widespread antibiotic use for strep throat. But in sub-Saharan Africa, South Asia, and the Pacific Islands, rheumatic heart disease remains a major cause of heart failure and death in young adults.
How Rheumatic Fever Is Diagnosed
Rheumatic heart disease develops after one or more bouts of rheumatic fever, so catching rheumatic fever early is the critical first step. Doctors use a diagnostic framework called the Jones Criteria, which sorts symptoms into major and minor categories.
The major signs of rheumatic fever include inflammation of the heart (carditis), joint swelling and pain that often migrates from one joint to another, involuntary jerky movements called chorea, a distinctive skin rash of pink rings with clear centers, and small painless lumps under the skin near joints. Minor signs include fever of 38.5°C (101.3°F) or higher, joint pain without visible swelling, elevated markers of inflammation in blood tests, and certain changes on an electrocardiogram.
A first episode of rheumatic fever is considered highly probable when a person shows either two major signs or one major sign plus two minor signs, alongside evidence of a recent strep infection. For recurrent episodes, the threshold is slightly different: even three minor signs can support a diagnosis if other causes are ruled out.
Confirming Valve Damage With Ultrasound
An echocardiogram, an ultrasound of the heart, is the definitive tool for identifying and grading rheumatic heart disease. The World Heart Federation established standardized criteria in 2012 to ensure consistent diagnosis, especially in screening programs across high-risk regions.
On ultrasound, doctors look for specific structural changes: thickening of the valve leaflets, thickening of the cord-like structures (chordae) that anchor the valve, and restricted or excessive leaflet movement. For a definite diagnosis in someone 20 or younger, the ultrasound needs to show abnormal blood leaking backward through the valve combined with at least two of these structural changes, or a pressure difference across the mitral valve indicating significant narrowing. A “borderline” category exists for cases where some structural changes are present but don’t yet meet the full threshold, helping identify people who need close monitoring.
Complications Over Time
Left untreated, rheumatic heart disease progressively worsens. The scarred valves force the heart to work harder, and the chambers gradually enlarge in response. The left atrium, the chamber just upstream of the mitral valve, is particularly prone to stretching. As it enlarges, the electrical signals that coordinate heartbeats become disorganized, leading to atrial fibrillation.
Atrial fibrillation is more than an uncomfortable sensation. When the atrium quivers instead of contracting effectively, blood pools and can form clots. Those clots can travel to the brain and cause a stroke. Research shows that people with atrial fibrillation caused by rheumatic valve disease have a higher stroke rate than those with atrial fibrillation from other causes. The combination of a damaged valve and an irregular rhythm makes stroke prevention a central concern in managing advanced disease.
Prevention Through Antibiotics
The most effective intervention happens long before the heart is involved. Treating strep throat promptly with antibiotics prevents rheumatic fever from developing in the first place. This single step is the reason rheumatic heart disease has nearly vanished in wealthy countries.
For someone who has already had one episode of rheumatic fever, the priority shifts to preventing recurrences, because each new episode adds more damage to the valves. This involves long-term antibiotic prophylaxis, typically an injection of penicillin every three to four weeks. The duration is individually tailored but generally continues at least until age 21. For people who already have established heart valve damage, prophylaxis may continue much longer, sometimes for life. This ongoing prevention is one of the most cost-effective interventions in global cardiovascular health, but it requires consistent access to healthcare, which is exactly what many high-risk populations lack.
Treatment for Advanced Disease
When the valve damage is severe enough to cause heart failure symptoms, treatment moves beyond prevention into managing the consequences. Medications can help control fluid buildup, regulate heart rhythm, and reduce the risk of blood clots, but they cannot reverse the structural damage to the valves.
For people with critical narrowing of the mitral valve, a procedure called balloon valvuloplasty can help. A thin catheter with a balloon tip is threaded into the heart and inflated inside the narrowed valve, stretching it open. This technique has been widely used in countries with high rates of rheumatic fever and produces good results for many patients, though the valve can narrow again over time.
When the valve is too damaged for repair, surgical replacement becomes necessary. This means removing the diseased valve and replacing it with either a mechanical valve (made of durable synthetic materials) or a biological valve (made from animal tissue). Mechanical valves last longer but require lifelong blood-thinning medication to prevent clots from forming on the valve surface. Biological valves don’t require the same level of blood thinners but wear out over 10 to 20 years and may eventually need replacement. For young patients in low-resource settings, this choice carries significant practical weight, since access to blood-thinning medication and regular monitoring may be limited.