In acute pericarditis, which electrocardiographic finding is most characteristic?

• A. Diffuse ST Segment Elevation
• B. Peaked T Waves
• C. Inferior Q Waves
• D. Loss of R-Wave Amplitude

Answer: (A)

Diffuse ST-segment elevation across most leads is the hallmark pattern in acute pericarditis. This widespread elevation comes from inflammation of the pericardium creating uniform injury currents around the heart, so many ECG leads show elevation rather than a localized pattern seen with a heart attack. The elevation is typically concave upward, and you may also see PR-segment depression in the same leads (with PR elevation in aVR), which helps distinguish pericarditis from infarction. In contrast, peaked T waves point to hyperkalemia or early ischemia, inferior Q waves suggest prior infarction, and loss of R-wave amplitude is not characteristic of acute pericarditis.