D3.351 - A case of Kounis syndrome in idiopathic anaphylaxis and indolent systemic mastocytosis

We present a case of a 55 yrs old man with a history of recurrent upon awakening syncopes with severe hypotension, face flushing, angioedema and palmoplantar itching. No drugs or food intake 10 hours before symptoms in all episodes. No food allergy was found. Tryptase level at baseline was 78 (ng/dl (normal range <11.4) in 3 different samples. During acute phase tryptase was not measured.

When he was 50 yrs old, during a syncope, he suffered thoracic pain and a ST segment depression was revealed at 12-lead electrocardiogram.

 As an atheromatous plaque erosion on right coronary artery was found at coronary angiography a stent was implanted. Cardiac biomarkers and troponin I raised.

REMA score was +7.

Bone marrow aspiration showed 50 mast cell aggregates CD117+,CD2+,CD25+,CD30- with atypical ovoid nucleus.

KIT mutation was present on peripheral blood.

Neither B or C–findings (SM-WHO criteria) were detected.

Our diagnosis was indolent mastocytosis (ISM) with recurrent idiopathic anaphylaxis associated to type II Kounis syndrome.

A second lecture of loop recorder showed recurrent transient ST segment elevation during syncopes confirming the suspect of recurrent Type I Kounis syndrome due to mast cell degranulation.

An adrenaline autoinjector and daily antihistamine medication were prescribed.

Coronary symptoms associated with conditions related to mast

cell activation

are currently

referred to as the Kounis syndrome. 

Anaphylaxis trigger are food allergy, hymenopthera and drug hypersensitivity and rarely mastocytosis.

Three variants of Kounis syndrome have

been described.

Type II variant

  refers to the syndrome in patients with quiescent preexisting

atheromatous disease; in such patients, the acute release of inflammatory mediators can induce either coronary artery spasm

with normal cardiac biomarker levels or coronary

artery spasm together with plaque erosion manifesting

as acute myocardial infarction.

Kounis syndrome is a complex cause of acute coronary

syndrome that requires proper diagnosis after multidisciplinary approach

and a rapid treatment of paramount importance.