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Kounis syndrome

Medically Reviewed

Allergic reaction leading to acute coronary syndrome.

Overview

Kounis syndrome is a rare and potentially life-threatening condition that represents the coexistence of acute coronary syndrome (ACS) with an allergic or hypersensitivity reaction. Also known as “allergic angina” or “allergic myocardial infarction,” it involves inflammation and vasospasm of the coronary arteries triggered by the release of inflammatory mediators during an allergic event. First described by Dr. Nicholas Kounis in 1991, the syndrome highlights the complex interaction between immunologic and cardiovascular systems and is increasingly recognized in clinical practice.

Causes

Kounis syndrome is caused by the release of histamine, leukotrienes, prostaglandins, and other inflammatory mediators during an allergic reaction. These substances can cause coronary artery vasospasm, plaque rupture, or stent thrombosis, leading to myocardial ischemia or infarction. Common triggers include:

  • Medications (antibiotics, NSAIDs, chemotherapy agents)

  • Foods (shellfish, nuts, dairy, etc.)

  • Insect stings or bites (bees, wasps, ants)

  • Contrast agents used in imaging procedures

  • Environmental allergens (pollen, latex)

The syndrome is categorized into three types:

  • Type I: Occurs in patients with normal coronary arteries due to coronary spasm alone

  • Type II: Occurs in patients with pre-existing atherosclerosis, where allergic mediators may trigger plaque rupture

  • Type III: Involves patients with drug-eluting stents, where allergic reactions cause stent thrombosis

Symptoms

The clinical presentation of Kounis syndrome includes signs of both an allergic reaction and cardiac ischemia. Common symptoms may include:

  • Chest pain or discomfort (similar to a heart attack)

  • Shortness of breath

  • Palpitations or irregular heartbeat

  • Flushing, hives, or skin rash

  • Swelling of the face, lips, or throat (angioedema)

  • Nausea or vomiting

  • Hypotension or shock in severe cases

Symptoms typically appear shortly after exposure to an allergen and may rapidly progress if not treated promptly.

Diagnosis

Diagnosis of Kounis syndrome involves identifying both cardiac and allergic components. Key diagnostic tools include:

  • Electrocardiogram (ECG): To detect ST-segment changes, arrhythmias, or other signs of ischemia

  • Cardiac biomarkers: Elevated troponin and CK-MB levels may indicate myocardial injury

  • Echocardiogram: To assess heart wall motion and ventricular function

  • Coronary angiography: May show coronary spasm, plaque rupture, or thrombosis

  • Allergy testing: Including serum tryptase and IgE levels to confirm allergic activation

  • Detailed history: Focusing on recent allergen exposure, medication use, or insect stings

A high index of suspicion is required, especially when allergic symptoms and chest pain occur simultaneously.

Treatment

Treatment of Kounis syndrome requires simultaneous management of the allergic reaction and cardiac involvement. Key aspects of treatment include:

  • Antihistamines: H1 and H2 blockers to counteract allergic reactions

  • Corticosteroids: To reduce inflammation and prevent late-phase allergic responses

  • Epinephrine: Used with caution in anaphylaxis, especially in patients with cardiac risk

  • Nitrates and calcium channel blockers: To relieve coronary vasospasm

  • Antiplatelet agents and anticoagulants: For patients with evidence of plaque rupture or stent thrombosis

  • Oxygen and intravenous fluids: For supportive care in hypotensive or hypoxic patients

Treatment should be guided by a multidisciplinary team including cardiologists and allergists, with close monitoring for recurrence or complications.

Prognosis

The prognosis of Kounis syndrome depends on the type of syndrome, severity of the allergic reaction, and timeliness of treatment. Patients with Type I generally recover well with appropriate management. Type II and III cases involving plaque rupture or stent thrombosis carry a higher risk of complications, including myocardial infarction and cardiac arrest. With early recognition and targeted therapy, most patients can recover fully. Preventive measures, such as allergen avoidance and medical alert identification, are crucial to reduce recurrence risk.

Medical Disclaimer

The information provided on this page is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.