A 38-year-old woman with a history of rheumatic heart disease presents with new-onset atrial fibrillation and haemodynamic instability. Clinical examination reveals a loud first heart sound and an opening snap. Which investigation is most appropriate to assess the degree of mitral stenosis and guide urgent management?

## Clinical Context Rheumatic mitral stenosis (MS) with new-onset atrial fibrillation and haemodynamic instability requires rapid, non-invasive assessment of valve area and transmitral gradients to guide urgent intervention (rate control, anticoagulation, or mechanical relief). ## Investigation of Choice: Transthoracic Echocardiography with Doppler **Key Point:** Transthoracic echo with Doppler is the gold standard, non-invasive investigation for quantifying mitral stenosis severity. It provides: - Mitral valve area (MVA) by planimetry or pressure half-time method - Mean transmitral pressure gradient - Left atrial size - Right ventricular systolic pressure (RVSP) - Assessment of other valve involvement (aortic, tricuspid) **High-Yield:** Severity classification of MS by MVA: - **Mild:** > 1.5 cm² - **Moderate:** 1.0–1.5 cm² - **Severe:** < 1.0 cm² **Clinical Pearl:** In acute haemodynamic instability with AF and MS, echo rapidly confirms severity and helps decide between medical rate control, urgent cardioversion, or mechanical intervention (PMBV or surgery). ## Why Transthoracic Echo? | Advantage | Relevance | |-----------|----------| | **Non-invasive** | Safe in acute haemodynamic instability; no contrast or arterial access | | **Rapid** | Can be performed at bedside; results available within 30 min | | **Quantifies severity** | MVA and gradients guide urgency of intervention | | **Assesses complications** | Detects LA thrombus, RV dysfunction, pulmonary hypertension | | **Guides intervention** | Echo findings determine suitability for PMBV vs. surgery | ## Comparison with Other Investigations | Investigation | Role in Acute MS + AF | |---|---| | **Transthoracic echo** | **Gold standard**; rapid, quantifies severity, guides intervention | | **Cardiac catheterisation** | Invasive; reserved for cases where echo is inconclusive or when coronary anatomy needed before surgery | | **Chest X-ray** | Shows pulmonary congestion, LA enlargement; does NOT quantify MS severity | | **ECG** | Shows AF, LAD; does NOT assess valve haemodynamics | | **Transoesophageal echo** | Better for LA thrombus detection if PMBV planned; not first-line for severity assessment | **Mnemonic:** MS assessment = **DOPPLER** - **D**oppler ultrasound (transthoracic echo) - **O**pening snap (clinical sign; echo confirms) - **P**ressure gradient (mean transmitral, measured by Doppler) - **P**lanimetry (MVA measurement) - **L**eft atrial size (assessed on echo) - **E**jection fraction (RV function assessed) - **R**ight ventricular pressure (RVSP estimated from TR jet)