Disclosures: Timothy S. Hake, MD: No financial relationships or conflicts of interest

Case Description: The patient presented with a 6 month history of progressive proximal weakness with muscle tenderness, dysphagia, and weight loss. Myopathy evaluation notable for elevated creatine kinase, negative anti-3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR) and anti-signal recognition particle (anti-SRP) antibodies, and chronic latent hepatitis B. Electrodiagnostic studies and muscle biopsy results were consistent with necrotizing myositis. Significant improvements in muscle strength were observed after initiation of immunosuppression with intravenous immunoglobulin, high-dose prednisone, and mycophenolate mofetil. His course was complicated by new palpitations and dyspnea. Cardiac evaluation revealed 1st degree atrioventricular block with trifascicular block and endomyocardial biopsy was consistent with myositis.

Setting: Academic tertiary medical center

Patient: A 45-year-old male with auto-antibody negative necrotizing myopathy with rare cardiac involvement. Assessment/

Results: This patient had functional declines due to delays in cardiac evaluation. With appropriate treatment the patient progressed with functional gains.

Discussion: Immune-mediated necrotizing myopathy (IMNM) can be broken into distinct subtypes – anti-HCGCR myopathy, anti-SRP myopathy, and auto-antibody negative myopathy. Per literature review, cardiac involvement is a rare component of IMNM and is most commonly associated with the anti-SRP subtype. It is uncommon for worsening cardiomyopathy with concurrent improvement in peripheral muscle strength with immunosuppressive therapy. There have been some rare reports of myopathy with chronic hepatitis B infection.

Conclusion: We will review systematic guidelines for appropriate initial management and provide evidence based practice guidelines to optimize a patient’s recovery regarding cardiac complications associated with newly diagnosed immune-mediated necrotizing myopathy.

Level of Evidence: Level V

« Back to AAPM&R Annual Assembly 2020

PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/auto-antibody-negative-necrotizing-myopathy-with-rare-cardiac-involvement-and-incorporating-evidence-based-treatment-guidelines/