Recovery of cardiac metabolic function after high-dose prednisolone in a patient with inflammatory myopathy associated with anti-mitochondrial antibody.

Unlabelled: Myocardial complications in the setting of inflammatory myopathy associated with anti-mitochondrial antibody (AMA) cause various cardiovascular complications. A 64-year-old Japanese man was diagnosed with inflammatory myopathy associated with AMA, and three years after diagnosis, the patient was referred to our hospital with leg edema and dyspnea on exertion. Right ventricular endomyocardial biopsy showed no disease-specific findings, with neither inflammatory cell infiltration nor non-caseating epithelioid cell granuloma, and only mild fibrosis; therefore, we finally diagnosed this patient with cardiac involvement in inflammatory myopathy associated with AMA. I-β-methyl--iodophenyl-pentadecanoic acid (BMIPP) cardiac scintigraphy showed decreased uptake in wider areas discordant with late gadolinium enhancement (LGE) on cardiovascular magnetic resonance (CMR). One month after starting prednisolone (PSL), the symptoms of congestive heart failure and left ventricular (LV) systolic function had improved. Additionally, BMIPP uptake in the LV myocardium significantly improved compared to that before PSL administration, although decreased BMIPP uptake remained in areas concordant with LGE on CMR. Moreover, it is suggested that recovery of cardiac metabolic function after high-dose PSL administration, which was confirmed through improvement in BMIPP uptake in the LV myocardium, may have led to the improvement in both LV systolic function and heart failure.

Learning Objective: Although the definitive diagnosis of cardiac involvement in inflammatory myopathy associated with anti-mitochondrial antibody is difficult because of the rarity of this condition and no disease-specific findings in imaging and histology, physicians should consider this in patients with cardiac dysfunction and muscle weakness. I-β-methyl--iodophenyl-pentadecanoic acid scintigraphy should be used to assess cardiac metabolic function and treatment efficacy and should be considered for patient management.