Kounis syndrome type III triggered by stents in patients with coronary artery disease: A review of clinical cases

Abstract

Kounis syndrome (KS) type III is a rare but life-threatening condition in which an acute allergic, anaphylactic, or anaphylactoid reaction precipitates acute coronary syndrome due to thrombosis or restenosis of a previously implanted coronary stent. The pathophysiological mechanism involves IgE-mediated or non-IgE-mediated mast cell activation, leading to coronary vasospasm, destabilization of atherosclerotic plaques, and intrastent thrombosis. Known triggers include various allergens such as medications (notably antibiotics and nonsteroidal anti-inflammatory drugs), metallic or polymeric stent components, and drugs eluted from the stent surface. A review of relevant clinical cases from PubMed and Scopus (1991-2025; 6 publications meeting the inclusion criteria, reporting 6 cases) showed a mean patient age of 66 ± 11 years, with a male predominance (4/6). Only 3 patients had a history of allergic disease. Clinical manifestations included chest pain (100%), cutaneous rash (2 cases), and ST-segment elevation on electrocardiogram (4 cases). Management included reperfusion therapy, corticosteroids, antihistamines, and dual antiplatelet therapy. Outcomes were generally favorable, although 1 patient died 3 years later due to KS-related complications. KS type III requires urgent recognition and simultaneous treatment of both the allergic reaction and coronary obstruction. In cases of unexplained stent thrombosis or restenosis, KS should be considered in the differential diagnosis.

Keywords: Kounis syndrome type III; Stent hypersensitivity; Allergic stent thrombosis; Coronary stent allergy; Acute coronary syndrome; Stent components; Eluted drugs

Core Tip: Kounis syndrome type III is a rare but life-threatening condition characterized by stent thrombosis or restenosis caused by allergic reactions to previously implanted coronary stent components, including metallic alloys, polymer coatings, and drugs eluted from the stent surface (e.g., sirolimus). A review of six clinical cases identified predominantly older male patients who uniformly presented with chest pain, while cutaneous rash was infrequent. Medications such as antibiotics and nonsteroidal anti-inflammatory drugs were identified triggers, underscoring the need for careful allergy assessment and prevention strategies.