Kounis syndrome (KS) is a rare condition characterized by acute coronary syndrome (ACS) triggered by an allergic reaction. This report presents a case of high-risk ACS associated with a food allergy. A 53-year-old male with no prior medical history presented to the emergency department with itching, facial swelling, chest tightness, shortness of breath, and presyncope after consuming peanut butter and grapefruit juice. His past medical history included an allergy to codeine/paracetamol, causing angioedema. Initial vitals were stable, and examination revealed minimal lip swelling, a pruritic rash, and clear auscultation. A baseline electrocardiogram (ECG) demonstrated subtle ST-segment depression with T-wave inversion in inferior leads, which progressed to significant ST depression and deep T-wave inversion. Serial troponin levels showed a significant rise (20.2 to 39.2 ng/L). Coronary angiography revealed no significant coronary artery disease. Cardiac magnetic resonance (CMR) excluded myocardial infarction or fibrosis. The patient was diagnosed with KS based on clinical presentation, dynamic ECG changes, and elevated troponins in the absence of obstructive coronary artery disease. Management included antihistamines, steroids, nitroglycerin, and standard acute coronary syndrome treatment. He was discharged on oral antihistamines after a brief coronary care unit observation.
