Which condition is the most likely cause of mitral stenosis in an adult patient with a history of preceding pharyngitis?

Mitral stenosis in an adult patient with a history of preceding pharyngitis is most commonly caused by rheumatic heart disease. This condition is a consequence of rheumatic fever, which can develop following an infection with group A Streptococcus bacteria, commonly leading to pharyngitis or strep throat.

During the immune response to the streptococcal infection, the body produces antibodies that may mistakenly attack not only the bacteria but also the heart tissue, causing inflammation and scarring. Rheumatic heart disease specifically affects the heart valves, particularly the mitral valve, leading to changes such as thickening and fibrosis, which can result in mitral stenosis, a narrowing of the valve opening.

The link between a prior throat infection and subsequent heart valve disease is particularly strong in rheumatic fever, making it a classic scenario for the development of mitral stenosis in adults with a history of pharyngitis.