A 32-year-old woman from rural India presents with progressive dyspnea and palpitations for 2 years. Echocardiography confirms mitral stenosis with a valve area of 1.2 cm². What is the most common cause of mitral stenosis in this patient?

Explanation

## Most Common Cause of Mitral Stenosis **Key Point:** Rheumatic heart disease (RHD) accounts for >90% of mitral stenosis cases globally, and remains the leading cause in India and developing nations despite declining incidence in developed countries. ### Pathophysiology of Rheumatic Mitral Stenosis 1. **Acute rheumatic fever (ARF)** → group A streptococcal pharyngitis 2. **Molecular mimicry** → cross-reactive antibodies attack valve tissue 3. **Acute carditis** → inflammation, edema, and valve regurgitation 4. **Chronic phase** → fibrosis, calcification, and commissural fusion 5. **Result** → progressive stenosis (may take 10–20 years) ### Why Rheumatic Mitral Stenosis is Most Common | Feature | Rheumatic MS | Congenital MS | Post-IE MS | SLE-related MS | | --- | --- | --- | --- | --- | | **Prevalence** | >90% globally | <1% | Rare | <1% | | **Geography** | Developing countries | Sporadic, worldwide | Sporadic | Sporadic | | **Age of onset** | 20–40 years | Infancy/childhood | Variable | Variable | | **Valve pathology** | Commissural fusion, fibrosis | Hypoplasia, abnormal leaflets | Vegetation, perforation | Verrucous lesions | | **Associated findings** | AF, MR, aortic involvement | Isolated, no other valve disease | Septic emboli, fever | Rash, arthritis, serositis | **High-Yield:** In India, the prevalence of RHD is 1–2 per 1000 population; it remains the leading cause of acquired valvular disease in young adults. **Clinical Pearl:** Mitral stenosis due to RHD typically presents 10–20 years after the initial episode of ARF, often with no clear history of acute carditis. **Mnemonic — Complications of Rheumatic MS:** **AFAR** — Atrial fibrillation, Fetal loss (pregnancy), Atrial thrombus, Right heart failure. ## Why Other Options Are Wrong - **Congenital mitral stenosis** is rare (<1% of mitral stenosis cases) and usually presents in infancy with cyanosis or failure to thrive, not in a 32-year-old woman with a 2-year history. - **Infective endocarditis** causes acute valve destruction and regurgitation, not stenosis; it is a rare cause of MS and would present with fever and septic phenomena. - **SLE** can cause verrucous endocarditis (Libman–Sacks lesions) but is an uncommon cause of hemodynamically significant MS; SLE-related valve disease is usually asymptomatic or causes regurgitation.