Acute coronary syndrome due to plaque erosion likely triggered by insect bites: a case series of Kounis syndrome.

Background: Kounis syndrome is the concurrence of acute coronary syndrome (ACS), including coronary spasm, acute myocardial infarction, and stent thrombosis due to an allergic and/or anaphylactoid insult. Case summary: We present two cases of Kounis syndrome likely triggered by insect bites, with plaque erosion demonstrated using optical coherence tomography (OCT). Three common findings were derived from this case series. First, the patients developed a rash after an insect bite followed by ACS. Second, immunoglobulin E levels were increased. Finally, OCT identified the aetiology of ACS in this case series as erosion of the culprit lesions. Discussion: Kounis syndrome, which is ACS following allergic reactions due to insect bites, is a rare complication. Kounis syndrome is probably not uncommon, but underdiagnosed. It is important for physicians to consider the treatment of Kounis syndrome in the complex course of ACS associated with allergic reactions. Furthermore, patients with a history of Kounis syndrome should avoid antigen exposure during secondary prophylaxis. In some cases, it may take several days from antigen exposure to the onset of ACS. Considering Kounis syndrome is beneficial for early diagnosis and appropriate treatment.