Contrast Media Side Effects and Kounis Syndrome: Timeo Danaos et Dona Ferentes

Kounis syndrome is defined as the occurrence of acute coronary events in the setting of allergic, hypersensitivity, or anaphylactic reactions. It is mediated by mast cell activation and the interaction of inflammatory cells, including T lymphocytes and macrophages. This process leads to the release of multiple inflammatory mediators, such as platelet-activating factor, histamine, neutral proteases (tryptase and chymase), arachidonic acid metabolites, cytokines, and chemokines. Kounis syndrome represents a unique form of acute vascular disorder that may involve not only the coronary arteries but also peripheral, cerebral, and mesenteric vessels as well as the venous system. Contrast media are widely used in diagnostic imaging to enhance visualization and characterization of pathological conditions. These agents can be administered via several routes, including oral, intravenous, intra-arterial, or rectal administration. Although most hypersensitivity reactions to contrast media are mild to moderate, severe complications such as anaphylaxis, cardiac arrest, and Kounis syndrome may occur. In particular, contrast media-induced Kounis syndrome has been associated with significant clinical consequences, including an increased risk of life-threatening cardiac events. This narrative review aims to summarize current evidence regarding contrast media-related adverse effects, with a focus on hypersensitivity reactions, Kounis syndrome, and associated cardiovascular complications. Emphasis is also placed on preventive strategies, including the importance of obtaining a detailed patient history of prior hypersensitivity reactions prior to contrast administration, to reduce the risk of recurrence and severe outcomes.