Mitral stenosis is most commonly caused by which condition?

• A. Atherosclerosis
• B. Infective endocarditis
• C. Rheumatic heart disease
• D. Hypertrophic cardiomyopathy

Answer: (C)

Mitral stenosis is most commonly caused by rheumatic heart disease. After an episode of rheumatic fever following a Streptococcus infection, chronic rheumatic valvulitis leads to fibrous thickening and fusion of the mitral leaflets and chordae tendineae. This narrows the mitral orifice, impairs diastolic filling, and causes elevated left atrial pressure with subsequent atrial enlargement and pulmonary hypertension. This pattern is why rheumatic disease is the leading cause of mitral stenosis, producing the characteristic diastolic murmur with an opening snap. In contrast, atherosclerosis primarily narrows arteries, infective endocarditis tends to cause valve destruction and regurgitation rather than chronic stenosis, and hypertrophic cardiomyopathy affects the myocardium and outflow tract rather than causing mitral valve narrowing.