Antisignal Recognition Particle Antibodies–Related Cardiomyopathy

Abstract

A 63-year-old woman was referred to our center for the workup of a 6-month history of diffuse myalgia and severe proximal weakness. Physical examination did not find any sign of heart failure. The patient had a medical history of diabetes mellitus. Serum creatine kinase and aldolase levels were increased at 2262 U/L (normal <195 U/L) and 19.9 U/L (normal <7.6 U/L), respectively. ECG showed sinus rhythm at 91 beats per minute with frequent ventricular extrasystoles and normal repolarization. Muscle biopsy of the quadriceps revealed necrotizing myopathy (Figure 1A) and antisignal recognition particle (SRP) antibodies were identified in serum (Figure 1B), consistent with the diagnosis of anti-SRP necrotizing myopathy. Cardiac involvement was documented at diagnosis with increased troponin level at 451 pg/mL (normal <14 pg/mL), and transmural gadolinium enhancement and hypokinesia of the anteroseptal wall on cardiac magnetic resonance (CMR) imaging (Movie I in the online-only Data Supplement). Coronary angiography was normal. The patient received 1 mg/kg/d of prednisone, plasma exchanges, and rituximab with a good efficacy. Clinical and biological …