Tabriz University of Medical Sciences Journal of Cardiovascular and Thoracic Research 2008-5117 18 2 2026 06 30 Transient Cold Hemagglutinin Disease (CHAD) during cardiac surgery: An unexpected complication from hypothermia 133 135 10.34172/jcvtr.33536 EN Andrea D'Alessio https://orcid.org/0000-0002-8708-0060 Ali Ansaripour Samail Shahjahan Joshua Oliver Charles Chan Vivek Srivastava Journal Article 10.34172/jcvtr.33536 2025 03 24 2025 11 29 A 74-year-old male with mild non-specific anaemia underwent elective mitral and tricuspid valve surgery. Following initiation of cardiopulmonary bypass (CPB), systemic cooling to 34℃ and cardioplegia at 4℃, upon cardiotomy, clumps of blood were noted in the left atrium and left ventricle. Activated clotting time (ACT) was confirmed to be in range. A blood sample from CPB machine demonstrated clumps when exposed to ice, with resolution when warmed to normal temperature. The patient was rewarmed to 37℃, subsequent cardioplegia doses were delivered warm and the heart chambers were washed out. Mitral and tricuspid valve repair were carried out uneventfully and the patient made an uncomplicated recovery. Positive direct antiglobulin test confirmed Cold hemagglutinin disease (CHAD), a form of autoimmune haemolytic anaemia involving IgM autoantibodies against red blood cells triggered by low temperature. Prompt intraoperative identification and subsequent modifications of surgical strategy averted potentially severe embolic and ischaemic complications.