Diffuse ST-segment elevations on ECG are most consistent with which diagnosis?

• A. Myocardial Infarction
• B. Atrial Fibrillation
• C. Pericarditis
• D. Pulmonary Embolism

Answer: (C)

Diffuse ST-segment elevations reflect inflammation of the pericardium, causing widespread injury currents across the heart. In acute pericarditis you typically see ST elevations in many leads that are often concave upward, and you may also notice PR-segment depression, which helps distinguish it from other causes. This broad, multipllead pattern contrasts with myocardial infarction, where ST elevations are confined to a single vascular territory and often show reciprocal changes; troponin is usually elevated in MI. Atrial fibrillation involves an irregular rhythm rather than a characteristic ST-elevation pattern. Pulmonary embolism can cause various ECG findings but not the diffuse, concerted ST elevations typical of pericarditis.