Inflammatory Myopathy with Cardiac Involvement Associated with Anti-Mitochondrial Antibodies

Aim: Anti-mitochondrial antibodies (AMA) positive myositis is an atypical and rare form with various characteristics. We aim to highlight these specificities through this case report.

Presentation of the Case: We present the case of a young woman diagnosed with frequent polymorphic ventricular extrasystoles and left ventricular dysfunction. Two years after, she developed asthenia and muscle weakness. Clinical and biological tests confirmed the diagnosis of myositis complicated by focal myocarditis. The immunological screening revealed negative antinuclear antibodies and positive AMA type anti-AMA-M2 and anti-M2-3E. A good clinical evolution was noted under corticosteroids and methotrexate.

Discussion: Cases of primary biliary cholangitis (PBC) or positive AMA associated with other autoimmune diseases such as systemic scleroderma, Sjögren syndrome, rheumatoid arthritis and myositis have been reported. AMA’s pathogenic role on the musculoskeletal and cardiac systems remains to be clarified.

Conclusion: Inflammatory myopathy associated with AMA is a rare and serious entity, characterized by a delayed diagnosis and frequent cardiac involvement, often indicating a heavy treatment.