A 28-year-old woman from rural Maharashtra presents with progressive dyspnea on exertion for 6 months and orthopnea. She has a history of recurrent sore throat in childhood. On examination, she has an irregular pulse (90–110 bpm), a loud S1, an opening snap at the apex, and a low-pitched diastolic murmur best heard at the apex in the left lateral decubitus position. Chest X-ray shows straightening of the left heart border and pulmonary congestion. Echocardiography reveals a thickened, domed mitral valve with restricted leaflet motion and a valve area of 1.2 cm². What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Mitral Stenosis (Rheumatic Heart Disease) ### Key Clinical Features **Key Point:** The combination of history of recurrent sore throat, loud S1, opening snap, low-pitched diastolic murmur (Carey Coombs murmur), and echocardiographic findings of a thickened, domed mitral valve with restricted leaflet motion and reduced valve area (1.2 cm²) is pathognomonic for mitral stenosis (MS) secondary to rheumatic heart disease (RHD). ### Pathophysiology of Rheumatic Mitral Stenosis 1. **Post-streptococcal autoimmune reaction** → molecular mimicry between Group A Streptococcus (GAS) M-protein and cardiac myosin 2. **Acute rheumatic fever (ARF)** → pancarditis with valve inflammation 3. **Chronic phase** → fibrosis, calcification, and commissural fusion of mitral leaflets 4. **Result:** Progressive narrowing of the mitral orifice, increased left atrial pressure, and pulmonary congestion ### Diagnostic Hallmarks of Mitral Stenosis | Feature | Significance | |---------|-------------| | **Loud S1** | Increased force of valve closure due to elevated LA pressure | | **Opening snap** | Abrupt halting of domed leaflet motion in early diastole | | **Diastolic murmur** | Low-pitched, rumbling, best at apex in left lateral decubitus | | **Irregular pulse** | Atrial fibrillation (common in chronic MS due to LA enlargement) | | **Straightening of left heart border** | LA enlargement on CXR | | **Valve area < 1.5 cm²** | Moderate-to-severe stenosis; normal = 4–6 cm² | **Clinical Pearl:** The opening snap occurs earlier in diastole when MS is more severe (higher LA pressure pushes leaflets open faster). The A2–OS interval shortens as severity increases. ### Echocardiographic Criteria for RHD Mitral Stenosis **High-Yield:** Echocardiography is the gold standard for diagnosis and severity assessment: - **Thickened leaflets** (>3 mm) with restricted motion - **Domed anterior leaflet** in systole (characteristic of RHD) - **Commissural fusion** (leaflets move together) - **Planimetry valve area:** Mild (1.5–2.5 cm²), Moderate (1.0–1.5 cm²), Severe (<1.0 cm²) - **Elevated transmitral gradient** on Doppler This patient's valve area of 1.2 cm² indicates **moderate stenosis**. ### Why This Is RHD and Not Acute Rheumatic Fever **Key Point:** This patient has **chronic, established mitral stenosis**, not acute carditis. ARF presents acutely with pancarditis (endocarditis, myocarditis, pericarditis), new or changing murmurs, and systemic features (fever, arthritis, chorea, erythema marginatum, subcutaneous nodules). This patient has a 6-month history of progressive dyspnea with structural valve changes — classic for chronic RHD. ### Management Implications - **Medical:** Diuretics, beta-blockers (rate control), anticoagulation if AF present - **Interventional:** Percutaneous mitral balloon commissurotomy (PMBC) if valve area 1.0–1.5 cm² and favorable anatomy - **Surgical:** Mitral valve replacement if severe stenosis, unfavorable anatomy, or failed PMBC **Mnemonic for RHD sequelae: MAST** - **M**itral stenosis (most common, ~65%) - **A**ortic regurgitation (second most common) - **S**tenosis of aortic valve - **T**ricuspid involvement (least common) [cite:Robbins 10e Ch 12]