Electrocardiogram features of acute pericarditis versus acute myocardial infarction

ECG features	Findings in acute pericarditis	Findings in acute MI
ST-segment elevation morphology	ST-segment elevation begins at J point, rarely exceeds 5 mm, normal concavity	ST-segment elevation begins at J point, often exceeds 5 mm in height, abnormal concavity (convex or "dome-shaped")
ST-segment elevation distribution	Widespread ST-segment elevation in most/all leads Typically most prominent in inferolateral leads	Anatomical groupings of leads show ST-segment elevation, which corresponds to vascular territory of infarction
Reciprocal ST-segment changes	Usually not seen	ST-segment depressions usually seen in reciprocal leads
Concurrent ST elevation and T-wave inversion	Unusual unless concomitant myocarditis	Common
PR segment changes	PR elevation in aVR PR depression in most/all other leads	Rare
Hyperacute T waves	Rare; if seen, due to fusion of elevated ST segment and T wave	Commonly seen at onset of acute infarction/ischemia
Q waves	Not usually new from acute pericarditis	Seen late in course of MI due to transmural injury
QT prolongation	Unusual	Can be seen

ECG: electrocardiogram; MI: myocardial infarction.

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