On ECG of an inferior STEMI patient, ST elevation is seen in leads II, III and aVF with reciprocal depression in I and aVL. Additionally, there is ST elevation of 1 mm in lead V4R. What does the V4R finding indicate and how does it change management?

• A Left ventricular anterior extension; add a second reperfusion agent
• B Posterior wall STEMI; posterior leads V7–V9 should be recorded for confirmation
• C Pericarditis complicating the infarct; aspirin dose should be increased
• D Right ventricular infarction; nitrates and diuretics are relatively contraindicated ✓

Explanation

ST elevation ≥1 mm in lead V4R (right precordial lead) is the hallmark of right ventricular infarction, occurring in up to 40% of inferior STEMIs due to proximal RCA occlusion. RV infarction causes preload-dependent physiology: the patient requires volume loading, and nitrates or diuretics must be avoided as they reduce preload and precipitate severe hypotension. Recognition is critical because management differs fundamentally from isolated LV infarction.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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