Which valve is primarily affected in rheumatic heart disease?

In rheumatic heart disease, the primary valve affected is the mitral valve. This condition typically arises as a complication of rheumatic fever, which is most commonly a result of untreated streptococcal throat infections. The inflammatory response triggered by the body’s immune system can lead to damage and scarring of the heart valves, particularly the mitral valve.

Mitral valve involvement often manifests as stenosis or regurgitation, resulting in complications such as heart failure or atrial fibrillation over time. The mitral valve is more frequently affected than other valves in rheumatic heart disease due to its greater exposure to the hemodynamic stresses of the left atrium and ventricle, combined with the unique anatomical and physiological properties of the left heart compared to the right. Although the aortic valve may also be involved in some cases, the predominant and most significant damage in rheumatic heart disease is observed in the mitral valve.

Other valves such as the tricuspid and pulmonary valves are much less commonly affected in this condition, which further emphasizes the mitral valve's central role in rheumatic heart disease.