Signal Recognition Particle Myopathy With Cardiac Manifestations in Rheumatoid Arthritis

Immune-mediated necrotizing myopathy is a rare inflammatory myopathy characterized by progressive muscle weakness and potentially severe systemic complications. A particularly aggressive subtype, signal recognition particle (SRP) antibody-associated myopathy, is frequently associated with cardiac involvement, including myocarditis and heart failure. We present a case of an older adult patient with rheumatoid arthritis (RA) who developed progressive muscle weakness accompanied by dyspnea, chest pain, and elevated creatine kinase levels consistent with inflammatory myopathy and cardiac dysfunction. Treatment with corticosteroids, intravenous immunoglobulin and rituximab led to marked clinical improvement. This rare association between RA and SRP-positive myopathy highlights the potential for autoimmune diseases to predispose individuals to complex, overlapping inflammatory syndromes. It underscores the importance of early recognition and aggressive immunosuppressive therapy for improving outcomes.