A Serial Assessment of T1 and T2 Mapping Cardiac Magnetic Resonance Before and After Heart Failure Onset in a Case of Cardiomyopathy in Anti-mitochondrial Antibody-positive Myositis.

A 69-year-old woman presented with heart failure and progressive muscle weakness and was diagnosed as anti-mitochondrial antibody (AMA) myositis with cardiac involvement. Immunosuppressive therapy with prednisolone and intravenous cyclophosphamide significantly improved the symptoms, hemodynamics, and cardiac function. Cardiac magnetic resonance (CMR) T1 and T2 mapping showed elevated native T1, T2, and extracellular volume fractions during heart failure exacerbation (day 37) compared to pre-hospitalization values (10 months before admission) and follow-up conducted 6 and 12 months after admission. This case underscores the importance of comprehensive evaluation, such as serial CMR imaging and immunosuppressive therapy, in managing myocardial involvement in AMA-positive myositis.