Intra-Stent Thrombosis Secondary to the Allergic Reaction by Contrast in Elective Percutaneous Coronary Intervention, a Rare example of Kounis Syndrome, a Case Report

Background: Kounis syndrome is the development of ACS secondary to allergic reaction. We are presenting case report of KS that developed due to allergic reaction in patient undergoing elective angiography and resulted in STEMI. Case Presentation 64year old female underwent elective PCI for angina refractory to anti-anginal therapy. CTCA demonstrated severe Diagonal 2 Coronary artery disease. Due to on-going angina she was listed for coronary angiogram +/- PCI. Iodixanol was used as contrast medium.This revealed severe disease in the D2. Initially drug coated balloon to D2 used. But DCB of D2 causes dissection. We decided to deploy 2.25x24mmDES overlapping with 2.5x14mmDES. Final results were satisfactory. In recovery urticarial rash noticed on her back. IV Hydrocortisone 100mg and IV Chlorphenamine 10mg was administered. Shortly after, she developed chest pain with ST elevation in lead 1 and aVL. She was immediately taken for PCI. Iohexol contrast was administered to the patient. There was acute stent thrombosis, which when re wired allowed flow to be restored and ECG changes to resolve. Patient developed severe hypotension. A widespread urticarial rash noted over the body with peri-orbital and facial swelling. Patient stabilised with iv adrenaline infusion and transferred to CCU. She was started on oral prednisolone. Patient developed pain in right Iliac fossae after removal of the femoral line next day. She developed abdominal distension and severe hypotension. Her CT AP showed large retroperitoneal hematoma with extravasation from external iliac artery. Via interventional radiology lower dose of Iohexol was used and a stent was inserted in EIA. Patient was moved to ICU. She was discharged home 4 days later with dual antiplatelet for 1 year followed by lifelong Aspirin. Discussion: This case was diagnosed with KS by Iodixanol as the source of anaphylaxis. There is need to treat KS as a separate entity in ACS guidelines.