Clinical Practice and Cases in Emergency Medicine

Introduction: Anaphylaxis is a life-threatening emergency that can involve significant cardiovascular manifestations. Transient electrocardiographic (ECG) changes during anaphylaxis and following epinephrine administration may closely mimic acute coronary syndrome, creating a diagnostic dilemma in the emergency department (ED). Failure to recognize these reversible patterns can result in delayed anaphylaxis treatment or unnecessary activation of invasive cardiac pathways.

Case Series: We report a case series of three adult patients presenting to the ED with anaphylaxis who developed alarming ECG changes, including ST-segment elevation, ST-segment depression, and hyperacute T waves. One patient demonstrated transient ECG changes temporally related to intramuscular epinephrine administration, while two patients exhibited features suggestive of hypersensitivity-associated coronary vasospasm or thrombosis manifesting as ECG changes. In all cases, serial ECGs, high-sensitivity cardiac troponin testing, and focused echocardiography revealed resolution of ECG abnormalities without dynamic biomarker elevation or regional wall motion abnormalities. All patients improved with prompt anaphylaxis-directed therapy and were managed conservatively without coronary intervention.

Conclusion: Transient ECG changes during anaphylaxis and after epinephrine administration can closely resemble acute coronary syndrome but may resolve completely with appropriate allergy-directed treatment. Serial ECG assessment, cardiac biomarkers, and focused echocardiography are essential tools for emergency physicians to differentiate transient allergic or catecholamine-mediated effects from true myocardial ischemia. Recognition of these patterns allows timely treatment of anaphylaxis while avoiding unnecessary invasive cardiac interventions.