Abstract 10980: Myositis, Myocarditis, and Mitochondria: A Thread Connecting the Myofilaments
A 67 year old man presented in 2013 with new heart failure symptoms. A curious past medical history prompted pursuit of an etiologic diagnosis. In 2006, he developed weakness and elevated creatine kinase (CK). Muscle biopsy was consistent with a necrotizing myopathy, and a serologic panel of auto-antibodies was unrevealing. He was started on prednisone. In 2011, he presented with atypical chest pain, and ECG demonstrated frequent atrial and ventricular ectopy. Both troponin-I and CK were elevated. Cardiac CT angiography ruled out obstructive coronary disease, and he remained stable until the onset of heart failure symptoms prompted his current admission. On examination, the patient had evidence of proximal muscle weakness and atrophy. His jugular venous pulse was elevated, and auscultation revealed an S3 gallop. Troponin (0.35 ng/mL) and CK (776 U/L) were both elevated and remained consistently so. Echocardiography revealed severely reduced left ventricular function.
Search for a unifying diagnosis prompted review of his myositis panel whereupon immunoprecipitation bands characteristic for anti-mitochondrial antibodies were discovered. Serologies for anti-mitochondrial antibodies returned positive. His plasma lactate was elevated with a normal pyruvate level, mimicking the changes seen in inborn errors of mitochondrial function. Cardiac magnetic resonance imaging showed patchy gadolinium enhancement in the mid-myocardium of the septum and lateral wall in a non-coronary distribution and no perfusion abnormalities. Endomyocardial biopsy established the presence of myocarditis, confirming the diagnosis of anti-mitochondrial antibody-associated myocarditis and myositis.
Along with a beta-blocker and diuretic (he experienced worsening renal insufficiency on low-dose ACE inhibitor), we initiated azathioprine at 50 mg up-titrating to a dose of 150 mg daily over several weeks. The patient reported no recrudescence of heart failure symptoms. Echocardiogram three months later revealed improved left ventricular function, and his CK and troponin-I levels normalized. In cases of idiopathic myositis and myocarditis, anti-mitochondrial antibodies may provide a unifying diagnosis and significantly alter management and prognosis.
Author Disclosures: B.A. Houston: None. S. Hsu: None. M. Halushka: None. A. Gelber: None. D. Judge: None.
- © 2015 by American Heart Association, Inc.