South African Flag Sign in Contrast-Induced Kounis Syndrome: When the Flag Misleads.

CASE SUMMARY: A 45-year-old woman with myasthenia gravis developed acute chest pain minutes after iodinated contrast administration. Electrocardiography showed high lateral ST-segment elevation. Emergent coronary angiography revealed no obstructive disease, with rapid resolution of ST-segment changes. Elevated troponin and regional wall motion abnormality were noted. The temporal association supported a diagnosis of type I Kounis syndrome.

TAKE-HOME MESSAGES: Contrast-induced hypersensitivity can mimic ST-segment elevation myocardial infarction, with characteristic electrocardiographic patterns. Urgent angiography remains essential when occlusive myocardial infarction cannot be excluded.