Background Amyloidosis can affect the heart, causing arrhythmia, thromboembolic events, and sudden cardiac death. Coronary sinus thrombosis is an uncommon though life-threatening condition which requires early identification and management.Case summary A 72-year-old Caucasian man, who recovered from out-of-hospital cardiorespiratory arrest, was diagnosed with coronary sinus thrombosis using cardiac imaging techniques. He had no history of invasive procedures and was diagnosed with cardiac amyloidosis based on an extra-cardiac biopsy positive for light chain amyloid, with consistent clinical, echocardiographic, and magnetic resonance criteria.Discussion A high frequency of intracardiac thrombosis is seen in amyloidosis. However, coronary sinus thrombosis is an uncommon complication. A multimodality imaging approach appears to be useful for the early diagnosis of coronary sinus thrombosis. The low specificity of the clinical signs, as well as the fast impairment of the patients, could result in fatal complications such as acute myocardial infarction, arrhythmia, and sudden death. Early screening, particularly in high-risk patients, as well as the use of early anticoagulant therapy, could reduce the associated morbidity and mortality.
