Coronary CT showed no obvious stenosis or plaque in the coronary artery.<h4>Outcome</h4>Results of an IgE_RAST test confirmed that the level of allergen_specific IgE for mackerel measured <0.10_UA/mL, while the level for anisakis was 1.91_UA/mL.<h4>Conclusions</h4>As for the mechanism leading to cardiac arrest, it is thought that the histamines and leukotrienes released from cardiac mast cells caused a coronary artery spasm (Kounis syndrome). The gene discussed is IGHE; the disease is cardiac arrest.