Abstract 4365902: Heart Failure in Anti-MDA5 Dermatomyositis: A Rare Manifestation of an Amyopathic Inflammatory Myopathy

Background: Anti-MDA5 dermatomyositis is a rare subtype of idiopathic inflammatory myopathy with high mortality, often due to interstitial lung disease (ILD). Myocardial involvement, although rarer, can be life-threatening. Early diagnosis and management can significantly impact outcomes. Case: A 47-year-old male with supposed history of rheumatoid arthritis (RA) presented with shortness of breath and had a cardiac arrest in the ED. He was found to have an ejection fraction of 10-15%. Ischemic evaluation and genetic testing were negative. Dermatologic findings of the Gottron sign, heliotrope rash, shawl sign, and mechanic’s hands were noted along with crackles in his lungs. Inflammatory markers were elevated but creatine kinase (CK) and aldolase were normal. Rheumatoid factor, anti-CCP, and anti-Jo-1 antibodies were negative. Myositis panel revealed high positive MDA-5 antibodies. Lung biopsy revealed ILD and endomyocardial biopsy showed evidence of inflammation. He was treated with steroids and intravenous immunoglobulin with inotropic support. Decision-Making: Anti-MDA5 dermatomyositis is known to be associated with high mortality related to rapidly progressive ILD. In contrast, this patient’s course was dominated by myocardial disease. Cardiac involvement in clinically apparent in only 10-20% of patients, and myocardial inflammation can lead to complications with poor outcomes. Furthermore, the lack of classic weakness and normal CK and aldolase posed a diagnostic challenge. Early diagnosis and initiation of anti-inflammatory therapy is essential to mitigate the high mortality rates associated with this elusive disease. Conclusion: This case illustrates the diagnostic challenges of anti-MDA-5 positive dermatomyositis, highlighting heart failure as a rare presentation.