The pattern of ST-segment elevation is important in the diagnosis of acute pericarditis. Another important feature of acute pericarditis is the widespread ST-segment elevation not corresponding with any specific arterial territory, which usually occurs in association with acute myocardial infarction. Also, reciprocal changes are absent in acute pericarditis, although they are frequently found with acute myocardial infarction. The ST segments in acute pericarditis return to baseline in a few days and are followed by diffuse T-wave inversion, in conjunction with the ST segment at baseline. 2 Loss of R-wave progression may occur with acute myocardial infarction, but this feature is not present with acute pericarditis.
Arrhythmias are uncommon in acute pericarditis.
Note the degree of ST-segment elevation is greater in the pericarditis complex than in the early repolarization complex. Important findings of acute infarction include the presence of Q waves and a more convex upward ST segment, both of which are present in the right complex. Differential Diagnosis of Acute Pericarditis by ECG Acute pericarditis exhibits characteristic changes on ECG that usually enable one to make the diagnosis readily. However, findings on the history and physical examination and on laboratory assessment usually narrow the diagnostic possibilities. Early repolarization is a normal variant that occurs commonly in young males, especially blacks, and does not evolve with the stages of acute pericarditis.