Kounis syndrome is defined as the co-incidental occurrence of an acute coronary syndrome with hypersensitivity reactions following an allergenic event and was first described by Kounis and Zavras in 1991 as an allergic angina syndrome.Multiple causes have been described and most of the data in the literature are derived from the description of clinical cases – mostly in adult patients – and the pathophysiology remains only partly explained.Three different variants of Kounis syndrome have been defined: type I (without coronary disease) is defined as chest pain during an acute allergic reaction in patients without risk factors or coronary lesions in which the allergic event induces coronary spasm that electrocardiographic changes secondary to ischemia; type II (with coronary disease) includes patients with pre-existing atheromatous disease, either previously quiescent or symptomatic, in whom acute hypersensitive reactions cause plaque erosion or rupture, culminating in acute myocardial infarction; more recently a type-III variant of Kounis syndrome has been defined in patients with preexisting coronary disease and drug eluting coronary stent thrombosis.
