Intraprocedure Type II Kounis Syndrome Secondary to Radioiodine Contrast During Coronary Angiography

An 83-year-old man with a previous right coronary artery (RCA) stent presented to the emergency department with syncope, dynamic lateral ST depression, and a serum troponin of 6148 ng/L (< 17). Coronary angiography revealed a patent proximal RCA stent and significant left-sided disease. The procedure was complicated by inferior ST elevation, urticaria, hypotension, and acute proximal RCA occlusion. This required stenting, which acted as a scaffold to ameliorate subsequent vasospasm that responded to intracoronary glyceryl trinitrate. Serum tryptase postprocedure was markedly elevated at 81.7 mg/L (<= 11.4) and subsequently normalized. This confirmed a rare presentation of intra-procedural type II Kounis syndrome likely due to radioiodine contrast.