A 57 year old female with history of systemic mastocytosis, hypertension and dyslipidemia presented to the emergency department with complaints of intermittent sub-sternal chest pain for 7 days. On presentation, vital signs were normal. Electrocardiogram (EKG) was done which revealed ST segment elevation in the anterior leads. Patient’s serum troponin I and CK-MB were also found to be elevated. An emergent coronary angiography was performed which revealed insignificant coronary vessel disease except for diffuse narrowing in the mid to distal left anterior descending artery. Coronary stent placement was attempted but was unsuccessful and the patient was managed medically. She subsequently underwent stress tests on follow up visits which were normal. The patient had no reoccurrence of symptoms on subsequent follow ups and Clopidogrel was discontinued.
Discussion:
Kounis syndrome is a concurrence of acute coronary syndromes, including coronary spasm, acute myocardial infarction and stent thrombosis in the setting of mast cell and platelet activation. It was first described by Dr Nicholas G Kounis in 1991. Kounis syndrome has been previously described in association with bee stings, foods, environmental toxins, coronary stents and medications. Acute coronary syndrome secondary to allergic reactions, are associated with significant morbidity and mortality in sensitised individuals. Mastocytosis is a rare disease with an annual incidence of 5-10 individuals per million. It is caused by the clonal proliferation of hematopoietic stem cells and can be limited or diffuse. Cardiac manifestation of mastocytosis are variable, with palpitations being the most common. Kounis syndrome should be considered as an etiology in patients with a history of mast cell disorder or prior known anaphylaxis, when presenting with an acute coronary syndrome. Diagnosis is challenging due to the short half life of inflammatory markers (tryptase, histamine), so a detailed history and physical examination is of paramount significance. Therapeutic management is also challenging as it requires simultaneous treatment of both cardiac and allergic manifestations. Drugs administered to treat cardiac manifestations may worsen allergic symptoms and vice-versa. Coronary evaluation is necessary in patients with acute coronary syndromes and management is based on presence or absence of atheromatous plaque or stent thrombosis. Suppression of allergic response involves use of corticosteroids, antihistamines and mast cell stabilizers. Epinephrine should be avoided as it can further precipitate coronary vasospasm.
Conclusions:
A detailed history and examination is of paramount importance in being able to identify uncommon causes of myocardial infarctions. Our case describes an unusual cause of an ST segment elevation myocardial infarction in a patient with systemic mastocytosis and the dilemma it poses in its diagnosis and management.