A 58-year-old man presents with 40 minutes of severe epigastric discomfort and diaphoresis. ECG shows horizontal ST depression of 3 mm in leads V1 to V3 with dominant R waves in V2 and upright T waves in those leads. There is no ST elevation in any lead. The next most appropriate step is:
- A Treat as acute posterior STEMI and proceed to emergency reperfusion ✓
- B Record right-sided leads V3R and V4R to exclude right ventricular infarction
- C Give sublingual nitrates and repeat the ECG in 30 minutes
- D Order serial troponins over 6 hours before deciding on therapy
Correct answer: A. Treat as acute posterior STEMI and proceed to emergency reperfusion
Explanation
Horizontal ST depression in V1 to V3 with dominant R waves and upright T waves is the classic mirror image of a posterior wall infarct, usually from left circumflex occlusion. It is a STEMI-equivalent mandating immediate reperfusion, not serial troponins or a wait-and-see approach. Right-sided leads detect right ventricular infarction, which shows ST elevation in V4R, not this pattern.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.