Kounis syndrome: a stinging case of ST-elevation myocardial infarction

Abstract

Kounis syndrome is not a rare but an infrequently diagnosed non-thrombogenic cause of angina or myocardial infarction triggered by the release of inflammatory mediators following an allergic or anaphylactic reaction. This so-called "allergic angina" is seen in the setting of anaphylactic reactions and is believed to be due to mast cell release causing coronary vasospasm. The treatment of such cases is often with epinephrine, which has also been described in the literature as another rare cause of coronary vasospasm. We present a case of Kounis syndrome seen in a 46 year-old male who suffered two bee stings while landscaping in his yard. He developed an anaphylactic reaction and was promptly treated with IM epinephrine injection by paramedics at arrival and developed marked ST elevations on EKG in the inferior leads with reciprocal ST depressions in the anterior leads. His troponin peaked at 13 ng/mL and tryptase level was 15 ng/mL (normal <10 ng/mL). Coronary catheterisation showed non-diseased coronary arteries and a normal ejection fraction without evidence of vasospasm. He was afterwards treated with an epinephrine drip for distributive shock. Interestingly this syndrome was not provoked when re-challenged with this therapy, suggestive of an allergic reaction rather than epinephrine as the aetiology of his presumed vasospasm. This patient's ST segment elevation and troponin elevation was due to Kounis syndrome. Awareness that anaphylactic reactions can lead to Kounis syndrome can lead to prompt appropriate treatment for this life threatening condition.

Keywords: Anaphylaxis; Epinephrine; Hymenoptera; Hypersensitivity; Myocardial Infarction.