Background: In hematologic patients undergoing repeated transfusions, iron overload may cause dilated cardiomyopathy and arrhythmias. After excluding coronary artery disease, tissue characterization by cardiac magnetic resonance (CMR) enables the diagnosis of cardiac siderosis. Case presentation: A 56-year-old man with a myeloproliferative neoplasm on ruxolitinib, candidate for allogeneic transplantation, had…