Kounis Syndrome is an acute coronary syndrome triggered by allergic or hypersensitivity reactions. It involves mast cell activation, leading to coronary artery spasm, plaque rupture, or stent thrombosis. Also known as allergic angina or allergic myocardial infarction, it reflects the interplay between immune and cardiovascular systems during anaphylactic events.
About the Kounis Syndrome
- Kounis Syndrome is a rare but potentially serious medical condition where an allergic reaction triggers acute coronary syndrome (ACS).
- It was first described by Dr. Nicholas Kounis in 1991 and is often referred to as “allergic myocardial infarction.”
- The syndrome results from the release of inflammatory mediators like histamine and leukotrienes during allergic or anaphylactic reactions, which can cause coronary artery spasm, plaque rupture, or even stent thrombosis.
- It is classified into three types: Type I (normal coronary arteries with spasm), Type II (pre-existing atherosclerosis with plaque disruption), and Type III (coronary stent thrombosis).
- Common triggers include drugs, foods, insect stings, and environmental allergens. Symptoms include chest pain, flushing, rash, and signs of cardiac ischemia.
- Diagnosis involves ECG, cardiac enzymes, allergy testing, and coronary angiography.
- Treatment includes managing both the allergic reaction and cardiac event, often using antihistamines, corticosteroids, and vasodilators. Prompt recognition is essential to improve outcomes.
Triggers of Kounis Syndrome
- Kounis Syndrome is triggered by various allergic and hypersensitivity-inducing agents that lead to mast cell activation and the release of inflammatory mediators affecting the coronary arteries.
- Common drug triggers include antibiotics (especially penicillins and cephalosporins), nonsteroidal anti-inflammatory drugs (NSAIDs), proton pump inhibitors, anesthetics, and contrast media used in imaging.
- Food allergens such as shellfish, peanuts, tree nuts, eggs, and milk can also provoke reactions. Insect stings and bites, especially from bees, wasps, and ants, are well-documented causes.
- Environmental factors like latex, pollens, dust mites, and chemicals are additional contributors.
- Vaccines, including COVID-19 vaccines in rare cases, have also been reported as triggers.
- Other stimuli like cold exposure, exercise, or idiopathic causes may be involved.
- The risk increases in atopic individuals or those with a history of severe allergies.
- The severity of coronary involvement depends on the intensity of the allergic reaction and the patient’s underlying cardiovascular health.
Types of Kounis Syndrome
Kounis Syndrome is classified into three main types based on the condition of the coronary arteries and the nature of the cardiac event:
Type I: Vasospastic Allergic Angina
- Occurs in patients with normal or near-normal coronary arteries.
- The allergic reaction causes coronary artery spasm due to the release of mediators like histamine and leukotrienes.
- There is no pre-existing coronary artery disease (CAD).
- Cardiac enzymes may be normal or mildly elevated.
- Often reversible with prompt treatment.
Type II: Allergic Myocardial Infarction
- Occurs in patients with pre-existing atherosclerotic coronary disease.
- The allergic reaction leads to plaque rupture or erosion, resulting in acute myocardial infarction (AMI).
- Cardiac markers are typically elevated.
- Requires both anti-allergic and standard ACS management.
Type III: Stent Thrombosis
- Occurs in patients with a history of coronary stent placement.
- The allergic reaction induces in-stent thrombosis.
- Histological examination shows eosinophils and mast cells in thrombi.
- Associated with poor outcomes and requires urgent intervention.
Each type represents a different pathophysiological mechanism, necessitating tailored treatment strategies.
Clinical Features of Kounis Syndrome
- Kounis Syndrome presents with a combination of allergic symptoms and acute coronary syndrome (ACS) manifestations.
- Patients typically experience sudden onset chest pain that may mimic angina or myocardial infarction.
- Common allergic symptoms include urticaria, flushing, itching, nasal congestion, bronchospasm, and throat tightness.
- In severe reactions, hypotension, syncope, and anaphylaxis may occur. Cardiovascular signs include palpitations, dyspnea, ECG changes (like ST-segment elevation or depression), and elevated cardiac biomarkers such as troponins.
- The clinical picture varies depending on the type of Kounis Syndrome: Type I may present with transient ischemia due to vasospasm; Type II with typical myocardial infarction signs in patients with underlying coronary artery disease; and Type III with symptoms of stent thrombosis such as recurrent chest pain post-stenting.
- A key feature is the temporal relationship between allergic exposure and cardiac symptoms, making clinical history critical for diagnosis. Prompt recognition is essential to initiate dual treatment for both allergy and cardiac involvement.
Diagnosis, Management, and Prognosis of Kounis Syndrome
Diagnosis of Kounis Syndrome
- Clinical History
- Recent exposure to allergens (e.g., drugs, insect stings, foods).
- Symptoms of allergic reaction plus chest pain.
- Physical Examination
- Signs of allergic reaction (rash, wheezing, hypotension).
- Cardiac signs (tachycardia, arrhythmia).
- Electrocardiogram (ECG)
- ST-segment elevation/depression.
- Arrhythmias or ischemic changes.
- Cardiac Biomarkers
- Elevated troponin and CK-MB indicate myocardial involvement.
- Allergy Markers
- Elevated serum tryptase and IgE support allergic involvement.
- Coronary Angiography
- Type I: Normal arteries with vasospasm.
- Type II: Atherosclerotic plaques or rupture.
- Type III: Stent thrombosis.
Management of Kounis Syndrome
Dual Approach – Treat both the allergic reaction and the cardiac event:
a) Allergic Reaction
- Antihistamines (H1 and H2 blockers)
- Corticosteroids
- Epinephrine (cautiously in cardiac patients – may worsen ischemia)
- Bronchodilators for bronchospasm
b) Cardiac Care
- Type I: Vasodilators like nitrates, calcium channel blockers
- Type II/III: Standard ACS treatment (aspirin, clopidogrel, statins, anticoagulants)
- Avoid: Beta-blockers (may worsen anaphylaxis), Morphine (histamine release)
Prognosis of Kounis Syndrome
- Type I: Often good with timely treatment and allergen avoidance.
- Type II: Risk of myocardial infarction and complications; depends on extent of CAD.
- Type III: Higher risk due to stent thrombosis; may require urgent intervention.
- Overall: Prognosis improves significantly with early recognition and appropriate management of both allergic and cardiac components.
Prevention of Kounis Syndrome
- Prevention of Kounis Syndrome involves avoiding known allergens in sensitized individuals, including specific drugs, foods, insect stings, or environmental triggers.
- Detailed allergy history must be taken before prescribing medications or performing procedures involving contrast media or stents.
- In high-risk patients, pre-medication protocols with antihistamines and corticosteroids may be used before surgeries or imaging.
- Patients with a known history should carry medical alert identification and epinephrine auto-injectors.
- Healthcare providers must be aware of this syndrome to ensure prompt recognition and avoid triggers.
- Regular follow-up and allergist consultation are essential for personalized allergen avoidance and safe medical care planning.
Conclusion
Kounis Syndrome is a rare yet critical condition linking allergic reactions to acute coronary events. Prompt recognition and simultaneous management of both cardiac and allergic components are vital. Awareness among clinicians can improve outcomes, highlighting the importance of considering Kounis Syndrome in patients presenting with chest pain after allergic exposure.
