In which condition would you expect to find symmetrical ST segment elevation on an ECG?

Symmetrical ST segment elevation on an ECG is most commonly associated with pericarditis. In this condition, inflammation of the pericardial sac leads to characteristic changes on the electrocardiogram, most notably symmetrical ST segment elevation across multiple leads, typically without reciprocal ST segment depression. This elevation tends to occur in a widespread pattern and often includes leads that reflect the affected areas of the heart, unlike the localized changes seen in myocardial infarction, where ST elevation is typically lead-specific.

In pericarditis, you may also see other associated features such as PR segment depression and may have a "saddle-shaped" appearance of the ST segment, further differentiating it from myocardial infarction. Symptoms such as chest pain that may worsen with deep breathing or lying down can accompany this condition as well, which helps clinicians identify the diagnosis when evaluating the ECG findings.

Myocardial infarction can cause ST elevation, but it usually presents in a more localized manner depending on the affected myocardial territory. Atrial fibrillation and heart block primarily affect the rhythm and conduction of the heart but do not typically cause ST segment elevation. Understanding these nuances is crucial for interpreting ECG findings accurately in clinical practice.