A 52-year-old woman with diabetes and dyslipidemia presents with acute anterior chest pain for 1.5 hours. ECG shows ST elevation in leads V1–V4 with reciprocal ST depression in II, III, and aVF. She is hemodynamically stable. She received aspirin 325 mg and clopidogrel 600 mg in the emergency department. The nearest PCI-capable hospital is 45 minutes away. Which investigation should be performed immediately to assess for right ventricular involvement and guide fluid management?

Explanation

## Right Ventricular Infarction: Diagnosis and Management ### Clinical Context This patient has **anterior wall STEMI** (ST elevation in V1–V4) with reciprocal changes. The question specifically asks about assessing for **right ventricular (RV) involvement**. **Key Point:** Right ventricular infarction occurs in 30–50% of inferior wall STEMIs but can also occur with anterior STEMIs, particularly when the right coronary artery (RCA) is the culprit vessel. RV involvement has critical implications for hemodynamic management. ### Why Right-Sided ECG (V3R–V4R)? 1. **Immediate and non-invasive:** Can be performed at the bedside in seconds 2. **Diagnostic accuracy:** ST elevation ≥1 mm in V4R has ~90% sensitivity and specificity for RV infarction 3. **Guides fluid management:** RV infarction is **preload-dependent**; patients require careful fluid administration (avoid diuretics) 4. **Time-sensitive:** Must be performed early to guide hemodynamic support before transfer to catheterization laboratory 5. **No delay to reperfusion:** Does not delay coronary angiography or PCI ### Hemodynamic Implications of RV Infarction | Finding | Management | |---|---| | **RV infarction present** | Maintain preload; cautious fluid administration | | **RV infarction + hypotension** | IV fluids (normal saline bolus 500 mL–1 L) | | **RV infarction + pulmonary edema** | Inotropes (dobutamine) preferred over diuretics | | **No RV infarction** | Standard STEMI management; diuretics if pulmonary edema | ### Right-Sided ECG Leads ```mermaid flowchart TD A[Anterior STEMI on standard ECG]:::outcome --> B[Obtain right-sided ECG<br/>V3R, V4R, V5R]:::action B --> C{ST elevation ≥1 mm<br/>in V4R?}:::decision C -->|Yes| D[RV infarction present]:::outcome D --> E[Maintain preload<br/>Cautious fluid administration<br/>Avoid diuretics]:::action C -->|No| F[RV infarction unlikely]:::outcome F --> G[Standard STEMI management]:::action E --> H[Proceed to coronary angiography]:::action G --> H ``` **High-Yield:** The mnemonic for right-sided ECG lead placement: - **V3R, V4R, V5R** = mirror image of left-sided leads (V3, V4, V5) - Placed on the **right side of the chest** at the same intercostal levels - **V4R** is the most sensitive and specific lead for RV infarction ### Why Other Investigations Are Inappropriate | Investigation | Limitation | |---|---| | **Transthoracic echo** | Operator-dependent; takes 10–15 minutes; does NOT guide acute hemodynamic decisions as rapidly as ECG | | **Cardiac CT angiography** | Time-consuming; delays transfer to catheterization laboratory; not indicated for acute STEMI diagnosis | | **PA catheterization** | Invasive; not needed for RV infarction diagnosis; reserved for refractory cardiogenic shock | **Clinical Pearl:** RV infarction is often overlooked because the standard 12-lead ECG does NOT include right-sided leads. Always obtain right-sided ECG in patients with inferior or anterior STEMI who present with hypotension or bradycardia, or when RV involvement is suspected. **Warning:** Do NOT give diuretics to a hypotensive patient with RV infarction — this worsens outcomes by reducing preload. The hemodynamic profile is opposite to left ventricular infarction. [cite:Harrison 21e Ch 297]