Hornet Sting-Induced Type I Kounis Syndrome Presenting as a Non-ST-Elevation Acute Coronary Syndrome: A Case Report.

Kounis syndrome is an acute coronary syndrome triggered by an allergic or anaphylactic reaction. Diagnosis can be challenging when epinephrine is administered during the same episode because both the allergic reaction and epinephrine may influence coronary vascular tone. We report the case of a 62-year-old man with no previous cardiac history who developed anaphylactic shock after a hornet sting to the upper lip. Acute constrictive chest pain began during the allergic reaction, before epinephrine administration. He was promptly treated with 0.55 mg of epinephrine, methylprednisolone, and dexchlorpheniramine. An electrocardiogram obtained during the acute episode showed ST-segment depression in leads III, aVF, and V3-V6. The chest pain and electrocardiographic abnormalities subsequently resolved. Troponin peaked at 208 ng/L. Transthoracic echocardiography showed preserved left ventricular systolic function without regional wall-motion abnormalities. Coronary angiography revealed only minor non-obstructive coronary irregularities, with no culprit lesion, and follow-up cardiac magnetic resonance imaging was normal. The overall presentation was consistent with type I Kounis syndrome, most likely caused by transient allergy-mediated coronary vasospasm. The onset of chest pain before epinephrine administration was an important element supporting the allergic coronary event as the primary mechanism.