Allergic Acute Coronary Syndrome (Kounis Syndrome)

Allergic Acute Coronary Syndrome (Kounis Syndrome) – A Medical Student Clinical Pearl

Amar Bhardwaj CC3

Dalhousie Medicine New Brunswick

Class of 2022

Reviewed and edited by Dr. Kavish Chandra

Copyedited by Dr. Mandy Peach


Case presentation

A 52-year-old female presents to the ED with sudden onset left sided chest with radiation to her left arm shortly after eating.  The patient is diaphoretic and has been experiencing exertional dyspnea since her meal.  Patient also noted they developed an itchy red rash on their face and torso. There was no evidence of angioedema or other classical clinical signs or symptoms of anaphylaxis.

The patient is otherwise healthy and has a family ischemic heart disease.

Her vitals are BP 160/90, temperature 36.4, HR: 152, RR: 20, Sats:98% O2 on room air. The cardiovascular and respiratory exam are otherwise normal. The ECG shows sinus tachycardia without evidence of other abnormalities.


Image source: Burns, Ed. “Sinus Tachycardia • LITFL • ECG Library Diagnosis.” Life in the Fast Lane • LITFL, 7 Feb. 2021,

Her hsTnT is 8 and the repeat marker is unchanged and the diagnosis of Kounis syndrome is considered.


Kounis syndrome

Kounis syndrome is defined as a concurrent acute coronary syndrome (ACS) in the setting of mast cell activation, which can be spontaneous or secondary to an allergic reaction (Lerner et al. 2017).  Kounis syndrome can be triggered by food, insect stings, drugs, environmental exposure and underlying medical conditions (Rodrigues et al. 2013). Allergen induced mast cell activation and release of inflammatory mediators leads to vasospasms, intimal thickening, and upregulation of proinflammatory cytokines that affect the coronary arteries and potential for occlusion progressing to an acute MI. The epidemiology remains scarce, and thus the prevalence is not entirely known as it is often missed or under diagnosed (Kounis, 2013; Kounis 2016).

Patients with Kounis syndrome can present with dyspnea, angioedema, pruritis, urticaria, gastrointestinal distress and hemodynamic instability. Airway compromise is of high importance in severe anaphylactic reactions with the potential to progress to anaphylactic shock. Along with an anaphylactic response, the coronary arterial effect can accelerate plaque rupture and cause symptoms indistinguishable from ACS.

Kounis Syndrome can be classified into three types (Kounis 2013)

Type I:

Acute coronary syndrome with normal or near-normal coronary arteries.

Type II:

Pre-existing atherosclerotic disease with syndrome causing coronary artery spasm, plaque rupture or erosion leading to acute MI.

Type III:

Coronary artery stent thrombosis with evidence of aspirated thrombus specimens containing eosinophils and mast cells respectively.



Patients with this Kounis syndrome typically present with anaphylactic signs and symptoms accompanied with chest pain and associated signs and symptoms of acute coronary syndrome.  Table 1 depicts pertinent signs and symptoms that may point you in the right direction.

Table 1. Clinical and laboratory findings in Kounis syndrome (Adapted from Kounis 2016)


Kounis syndrome is a clinical diagnosis.


There are no guidelines addressing the management of Kounis syndrome. However, treatment needs to address any hemodynamic instability as well as the cardiac and allergic concerns. Involvement of cardiology and allergy specialists can be helpful.

Concurrent management of anaphylaxis does not generally interfere with management of ACS however careful analysis of the risks and benefits of epinephrine administration to treat anaphylaxis without exacerbating cardiac ischemia. Case reports describe the successful treatment of Kounis syndrome patients with intramuscular epinephrine (Lerner et al. 2017). Other agents that have shown to aid symptomatically in allergic responses are H1 and H2 blockers as well as systemic corticosteroids for prevention of potential delayed phase reactions.

ACS management may be guided by cardiology and does not differ from traditional management with the exception that aspirin may be omitted due to its potential role propagating anaphylaxis (Lerner et. 2017). Other anti-platelets can be administered however beta-blockers are avoided as analgesics like morphine (further histamine release; Lerner et al. 2017). The timing and role of cardiac catheterization will be guided by cardiology and may involve intracoronary vasodilator infusion or thrombus evacuation (Carr and Helman, 2016).


In a patient presenting with ACS and severe allergic reaction/anaphylaxis, consider Kounis syndrome. There are no guidelines to assist in the management but the key aspects of managing ACS and anaphylaxis are critical in treating Kounis syndrome as well early consultation with cardiology and allergy.

Carr, D. Helman A. Anaphylaxis and Anaphylactic Shock. Emergency Medicine Cases. February, 2016.

Kounis, N. G. (2016). Kounis syndrome: an update on epidemiology, pathogenesis, diagnosis and therapeutic management. Clinical Chemistry and Laboratory Medicine (CCLM), 54(10), 1545-1559
Kounis, N. G. (2013). Coronary hypersensitivity disorder: the Kounis syndrome. Clinical therapeutics, 35(5), 563-571.

Lerner M, Pal RS, Borici-Mazi R. Kounis syndrome and systemic mastocytosis in a 52-year-old man having surgery. CMAJ. 2017 Feb 6;189(5):E208-E211. doi: 10.1503/cmaj.151314. Epub 2016 Aug 2. PMID: 27486207; PMCID: PMC5289872.

Mattu, A. Demeester, S. Cardiology Corner: Kounis Syndrome. EMRAP. June, 2021.

Rodrigues MC, Coelho D, Granja C. Drugs that may provoke Kounis syndrome. Braz J Anesthesiol. 2013 Sep-Oct;63(5):426-8. doi: 10.1016/j.bjan.2013.04.006. PMID: 24263049.


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