Which of the following is the most common etiology of mitral stenosis in India and other developing countries?

Explanation

## Etiology of Mitral Stenosis in India ### Most Common Cause: Rheumatic Heart Disease **High-Yield:** Rheumatic heart disease (RHD) secondary to **acute rheumatic fever (ARF)** is the predominant etiology of mitral stenosis in India and developing countries, accounting for >90% of cases. ### Pathophysiology of RHD-Induced Mitral Stenosis **Key Point:** ARF causes pancarditis, leading to: 1. Acute inflammation of valve leaflets and commissures 2. Healing with fibrosis, thickening, and commissural fusion 3. Progressive stenosis over years to decades 4. Eventual calcification in advanced disease **Clinical Pearl:** Mitral stenosis is the **most common valvular lesion in RHD**, often presenting 10–20 years after the initial ARF episode. Many patients do not recall the acute illness. ### Epidemiological Context **Mnemonic:** **RHD = Rheumatic Heart Disease = Recurrent streptococcal infection + Inadequate antibiotic prophylaxis** (in developing nations with limited access to penicillin prophylaxis) ### Comparison of Etiologies | Etiology | Prevalence (India) | Age of Onset | Associated Features | | --- | --- | --- | --- | | **Rheumatic Heart Disease** | >90% | 20–50 years | History of ARF, atrial fibrillation, thromboembolic events | | **Degenerative calcification** | <5% | >60 years | Aortic stenosis, chronic kidney disease, diabetes | | **Congenital mitral stenosis** | <2% | Childhood/adolescence | Parachute mitral valve, supravalvular ring | | **Infective endocarditis** | <1% | Variable | Acute presentation, septic phenomena | **Warning:** Do not confuse mitral stenosis etiology with aortic stenosis. Degenerative calcific aortic stenosis is common in developed countries, but degenerative mitral stenosis is rare. In India, always think RHD first for mitral stenosis.