Kounis syndrome in real-world practice: prevalence, triggers, and clinical outcomes
M Duarte Almeida, F R Santos, J G Fiuza, G R M Ferreira, O C Kungel, L A Santos, N CraveiroAbstract
Introduction
Kounis syndrome refers to the occurrence of an acute coronary syndrome in the setting of a hypersensitivity reaction, leading to the release of inflammatory mediators. These mediators can induce coronary vasospasm, plaque instability, or thrombosis, ultimately resulting in myocardial infarction. Three variants have been described: type I occurs in patients with normal coronary arteries, type II in those with pre-existing atherosclerosis, and type III in patients with coronary stents who develop stent thrombosis. This entity is likely underdiagnosed due to its variable clinical presentation.
Purpose
This study aimed to analyse the prevalence of Kounis syndrome among patients admitted to our hospital, in order to better understand its epidemiology and current diagnostic and therapeutic management.
Methods
Retrospective data were collected over a three-year period (2023 to 2025) from hospitalizations due to myocardial infarction. Patients with suspected Kounis syndrome were identified. Demographic characteristics, laboratory and imaging findings, and clinical outcomes were recorded.
Results
Three cases were identified—two women and one man—with a mean age of 58 ± 11.4 years. Cardiovascular risk factors included hypertension (n=1), diabetes (n=1), dyslipidaemia (n=2), and overweight (n=1). The suspected triggers were drugs in two cases (tramadol and acemetacin) and wasp venom in one. Two patients were suspected to have type II Kounis syndrome, and one type I. ST-segment elevation was observed in one case, who experienced cardiac arrest. All patients underwent coronary angiography; in one, thrombus aspiration and stent implantation in the left anterior descending artery were performed. Left ventricular dysfunction occurred in one case. Cardiac magnetic resonance imaging was performed in two patients, showing subepicardial late gadolinium enhancement consistent with myocarditis. Measurement of serum IgE and tryptase was obtained in two patients, with elevated levels in one that normalized at follow-up. Allergy testing confirmed sensitivity to the suspected agent in one patient. Only one patient received antihistamines and corticosteroids during hospitalization. At discharge, prescribed medications included anticoagulants/antiplatelets (n=2), statins (n=3), ACE inhibitors (n=2), and beta-blockers (n=2). Both in-hospital and 30-day survival rates were 100%.
Conclusions
Kounis syndrome should be considered in patients presenting with myocardial infarction following exposure to a potential allergen, as early recognition has important therapeutic implications. Identifying and avoiding the triggering agent is crucial. Given its potentially life-threatening nature, raising awareness among clinicians is essential. Reporting such cases contributes to a better understanding of the true incidence of this underdiagnosed condition and supports future research aimed at refining diagnostic criteria and optimize therapeutic strategies.For image description, please refer to the figure legend and surrounding text.