A Case of Cardiac Amyloidosis Showing Diagnostic Usefulness of Cardiac Magnetic Resonance T1 Imaging

Novel cardiac magnetic resonance T1 imaging technique enables us to quantitatively assess diffuse myocardial disease. We here report a case where native T1 was useful to diagnose cardiac amyloidosis. A 73 years-old man was admitted to our hospital for the treatment of his multiple myeloma. He had been treated with bortezomib and dexamethasone without any relapses since 2012. However, in 2017, serum level of BNP was elevated (from 12.2 to 243.4 pg/mL) and Holter ECG showed an increase in the number of premature ventricular contractions. He did not have shortness of breath or other subjective symptoms. Echocardiography showed that left ventricular ejection fraction was 60%, interventricular septum 10 mm, transmitral peak early (E) and late (A) flow velocity was 0.68 m/s and 0.52 m/s, respectively. Cardiac magnetic resonance imaging showed that although there was no late gadolinium enhancement, interventricular wall thickness was increased and native T1 was elevated. Then, we performed cardiac catheterization and myocardial biopsy to examine possible chemotherapy-induced cardiotoxicity and cardiac amyloidosis. Histological examination showed that cardiac tissues had amyloid fibrils with apple-green birefringence under polarized light, making the final diagnosis of cardiac amyloidosis. We thus changed bortezomib to melphalan because the former has been reported to cause cardiac dysfunction and ventricular arrhythmias. In this case, native T1 was useful to diagnose cardiac amyloidosis.