What ECG change is expected in acute pericarditis?

In acute pericarditis, the most notable ECG change is the diffuse ST segment elevation across multiple leads. This finding is significant because it distinguishes acute pericarditis from other conditions that can cause chest pain, such as myocardial infarction. In acute pericarditis, the ST segment elevation is typically concave upward and can be seen in virtually all leads except for V1 and aVR. This diffuse elevation occurs due to the inflammation of the pericardium, which irritates the epicardial surface and alters the repolarization of the myocardium.

The ST segment elevation in acute pericarditis is an early manifestation and may progress as the condition evolves. It's important to recognize this pattern in order to differentiate pericarditis from other cardiac issues which may present with more localized ST segment changes. This understanding is crucial for accurate diagnosis and appropriate management of the patient.