A rare presentation of a rare problem: mitral annular calcification-related calcific amorphous tumour with cavitation and left ventricle to left atrium communication-a case report.

Background: Mitral annular calcification (MAC) is common in ageing and in patients with renal failure, often considered benign. Calcified amorphous tumour (CAT) associated with MAC is rare but can cause severe complications. Case summary: A 71-year-old male with end-stage renal disease developed acute heart failure due to severe mitral regurgitation caused by MAC-related CAT. Discussion: This is the first reported case of a central coaptation defect and a left ventricle-CAT-left atrium communication, leading to severe mitral regurgitation. The potential for MAC-related CAT to cause severe complications, including catastrophic heart failure, should be recognized by the cardiology community.