Clinical characteristics, management, diagnostic findings, and various etiologies of patients with Kounis syndrome. A systematic review

Background: Kounis syndrome (KS) is defined by the association of acute coronary syndrome secondary to an anaphylactic reaction. KS is often underdiagnosed, and new etiologies have been proposed. Aims: To synthesize the available evidence on clinical profile, management, diagnosis, and etiologies in patients with KS. Methods: A search was conducted in the following databases: PubMed, Scopus, EMBASE and Web of Science from inception to March 19th, 2024. Case reports, case series, and observational studies were included. Letters to the editor, editorials, comments, notes, narrative reviews, and systematic reviews were excluded. Results: A total of 190 studies were included (174 case reports, 13 case series, and 3 observational studies, 214 patients). A predominance of male gender was observed (69.63 %). Mean age was 54.4 ± 16.5 years. The most common comorbidities were hypertension (33.64 %), diabetes (16.82 %), and dyslipidemia (16.35 %). The most frequent clinical manifestations were chest pain (66.35 %) and difficulty breathing (34.11 %). Three variants of KS were identified: type I or allergic coronary vasospasm was the most frequent (43.46 %), and type III, the least common (8.88 %). The most frequent etiology was drug use (38.32 %), primarily antibiotics (42.68 %), followed by animal stings or bites (26.17 %). The calculated KS rate was 11.12 per 1000 people. The mortality rate was 7.47 %, and the majority had a favorable outcome (86.92 %) after management. Conclusions: KS is a complex and underdiagnosed disease that should be considered as a differential diagnosis in acute coronary syndrome associated with an allergic reaction.