| 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 | | - ST-segment depressions usually seen in reciprocal leads
|
| Concurrent ST elevation and T-wave inversion | - Unusual unless concomitant myocarditis
| |
| PR segment changes | - PR elevation in aVR
- PR depression in most/all other leads
| |
| 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 | | |
