Unmasking Myopericarditis Behind an ST-Segment Elevation Myocardial Infarction (STEMI) Presentation.

Myopericarditis is an inflammatory cardiac condition that can closely mimic ST-elevation myocardial infarction (STEMI), presenting with chest pain, elevated troponin levels, and ST-segment changes on electrocardiogram (ECG). We present the case of a 46-year-old man with a history of hypertension who presented to the emergency department with sudden-onset, substernal chest pain that awoke him from sleep. The pain was described as crushing in nature, associated with diaphoresis, and was initially attributed to anxiety. Electrocardiography revealed ST-segment elevations in leads II, III, and aVF, with reciprocal changes and an incomplete right bundle branch block (IRBBB). Initial troponin I was markedly elevated at 16.9 ng/mL. Given these concerning findings, the patient underwent emergent cardiac catheterization. Coronary angiography revealed no obstructive coronary artery disease, and left ventriculography demonstrated preserved systolic function. Further evaluation uncovered a recent viral upper respiratory infection, and transthoracic echocardiography showed diastolic dysfunction with a trivial pericardial effusion. The combination of clinical presentation, elevated cardiac markers, ST-segment changes, and absence of coronary pathology led to the diagnosis of myopericarditis. This case highlights the importance of maintaining a broad differential diagnosis in patients presenting with apparent acute coronary syndromes and underscores the need for comprehensive assessment to avoid unnecessary interventions.