Pericarditis, or inflammation of the pericardium, has typical ECG findings
These findings occur in progressive stages, all of which are seen in about 50% of cases of pericarditis:
Stage I (acute phase): Diffuse concave upward ST segment elevation in most leads, PR depression in most leads (may be subtle) and sometimes notching at the end of the QRS complex.
Stage II: ST segment elevation and PR depression have resolved and T waves may be normal or flattened.
Stage III: T waves are inverted, and the ECG is otherwise normal.
Stage IV: T waves return to the upright position, and thus the ECG is back to normal.
Note: The ECG changes with pericarditis must be distinguished from those of early repolarization. The ST segment elevation seen in early repolarization is very similar ― diffuse and concave upward. However, three things may help to distinguish pericarditis from early repolarization:
The ratio of the T wave amplitude to the ST elevation should be greater than 4 if early repolarization is present, meaning the T wave in early repolarization is usually 4 times the amplitude of the ST segment elevation. Another way to describe this would be that the ST segment elevation is less than 25% of the T wave amplitude in early repolarization.
The ST segment elevation in early repolarization resolves when the person exercises.
Early repolarization, unlike pericarditis, is a benign ECG finding that should not be associated with any symptoms.