Abstract Background Intramyocardial dissecting haematoma (IDH) is a rare life-threatening event usually complicating an acute myocardial infarction. Poor data exist about diagnosis, management, and outcome. Case summary We reported a case of giant IDH managed conservatively, thanks to stable clinical status and haemodynamics, which evolved towards resorption. Echocardiography and second-level imaging tools, like computed tomography scan and cardiac magnetic resonance, helped in differential diagnosis and studying the haematoma evolution over time, especially providing data about dimension, connection with the left ventricular cavity, consolidation, and resorption. The course is influenced by many factors including localization, edge integrity, and antithrombotic therapy on board. In this case, IDH resorption was observed despite the huge size and anticoagulant therapy on board, used for secondary cardioembolic protection, under close imaging follow-up. Discussion Intramyocardial dissecting haematoma management depends on clinical stability, and imaging provides key data about diagnosis and evolution.