D1.06 - When an alergic reaction turns into a cardiac event: clinical characterization of Kounis Syndrome

Kounis syndrome (KS) is an acute coronary syndrome triggered by an allergic reaction, in which mast-cell activation and the release of inflammatory mediators induce coronary vasospasm, plaque rupture, or stent thrombosis. KS is classified into three clinical variants: type I (vasospasm in previously normal coronary arteries), type II (ischemic events superimposed on underlying coronary disease), and type III (stent thrombosis). The objective of this study was to analyze the characteristics of patients diagnosed with KS in our Allergy Department.

A retrospective descriptive study was conducted including all patients diagnosed with KS and evaluated in our hospital between 2018 and 2025. Clinical records were reviewed to determine the trigger, allergic background, clinical features, and classification subtype.

Nine patients were diagnosed (2 women and 7 men), with a mean age of 58.6 years. Most patients were current or former smokers (66.7%). KS type I was the predominant form (77.8%), followed by one case each of type II and type III. Diagnosis was first established in Allergy (3 patients), Cardiology (3), and less frequently in Anesthesiology (intraoperative) (1), ICU (1), and Emergency Medicine (1).

A history of atopy was present in 33.3% of patients. Besides cardiac manifestations (88.9%), cutaneous symptoms were the most frequent (77.8%). Drugs were the leading triggers (55.6%), followed by foods and one case associated with mast-cell disease. Among drugs, β-lactams accounted for 60% of reactions. Cofactors were present in 66.7% of cases (NSAID intake, alcohol, or physical exercise). All patients required treatment, though adrenaline was administered in only three cases (33.3%). Troponins increased in all but one patient. Serum tryptase was measured in three patients and was elevated in every case.

Kounis Syndrome in our cohort predominantly presented as type I and was most frequently triggered by medications—especially β-lactams—often in the presence of cofactors. The high rate of extracardiac allergic symptoms and the consistent elevation of biomarkers underscore the importance of considering KS in patients with concurrent allergic manifestations and acute coronary symptoms. Improved awareness and systematic allergological evaluation may enhance early recognition and optimize patient management.