A 52-year-old man from Delhi presents with progressive dyspnea on exertion and orthopnea for 3 months. On examination, he has a loud S1, an opening snap, and a low-pitched diastolic murmur best heard at the apex in the left lateral decubitus position. Chest X-ray shows pulmonary congestion and straightening of the left heart border. Which investigation is most appropriate to assess the severity of mitral stenosis and guide management?

Explanation

## Investigation of Choice for Mitral Stenosis Severity Assessment ### Clinical Context The patient presents with classic features of mitral stenosis: opening snap, diastolic murmur at the apex (best heard in left lateral decubitus), and signs of left atrial hypertension (pulmonary congestion, straightened left heart border on CXR). ### Why Transthoracic Echocardiography with Doppler is Correct **Key Point:** Transthoracic echocardiography with Doppler is the **first-line, non-invasive gold standard** for diagnosing and assessing the severity of mitral stenosis. **High-Yield:** Doppler echocardiography provides: - Mitral valve area (MVA) calculation using continuity equation or planimetry - Mean transmitral pressure gradient - Left atrial size and function - Right ventricular systolic pressure (RVSP) estimation - Assessment of associated lesions (MR, AR, TR) **Clinical Pearl:** Severity grading of mitral stenosis: | Severity | MVA (cm²) | Mean Gradient (mmHg) | Peak Velocity (m/s) | |----------|-----------|----------------------|-----------| | Mild | >1.5 | <5 | <1.5 | | Moderate | 1.0–1.5 | 5–10 | 1.5–2.2 | | Severe | <1.0 | >10 | >2.2 | **Key Point:** This investigation directly guides clinical decisions: - Mild MS: medical management, endocarditis prophylaxis - Moderate MS with symptoms: consider percutaneous mitral commissurotomy (PMC) or surgery - Severe MS: intervention indicated ### Diagnostic Accuracy Echocardiography has >95% sensitivity and specificity for hemodynamically significant mitral stenosis and is non-invasive with no radiation. [cite:Harrison 21e Ch 282] --- ## Why Other Options Are Not Ideal **Cardiac catheterization:** Invasive procedure reserved for cases where echocardiography is inconclusive or when coronary angiography is needed (e.g., to exclude CAD before surgery). Not first-line. **Transesophageal echocardiography (TEE):** Indicated when transthoracic windows are poor, for assessment of thrombus in the left atrial appendage (before PMC), or for intraoperative guidance—not for initial severity assessment. **Exercise stress echocardiography:** Useful to assess functional capacity and dynamic changes in gradient during stress, but not the primary investigation for initial severity assessment.