Atrioventricular Dissociation With Ischemic-Appearing ST-Segment Changes

BACKGROUND: ST-segment elevation in a wide-complex rhythm may signal acute coronary occlusion, a critical cannot-miss diagnosis, but also brings a broad differential with diagnostic and triaging challenges, especially in patients presenting with shock. CASE SUMMARY: A 46-year-old woman with unknown past medical history presented with fever, chest pain, and hemodynamic instability concerning for shock. Electrocardiogram demonstrated high-grade atrioventricular block with a wide-complex ventricular rhythm and anterior ST-segment changes, raising concern for acute coronary syndrome. Emergent coronary angiography revealed normal coronary arteries, and she was found to have severe left ventricular systolic dysfunction consistent with fulminant myocarditis complicated by diffuse conduction disease with an accelerated idioventricular rhythm. DISCUSSION: Diffuse myocardial inflammation from fulminant myocarditis can disrupt atrioventricular conduction and cause ischemic-appearing ST-segment changes, signifying a poor prognosis. TAKE-HOME MESSAGES: There is a broad differential for ST-segment abnormalities, and fulminant myocarditis should be considered in patients with inflammatory symptoms, conduction disease, and cardiogenic shock after exclusion of acute coronary syndrome.