No 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 relapse occurred 5 months later, leading to adjunction of methotrexate with a remission of the disease.Six months later, after discontinuating all treatments by herself, she presented a new relapse of myopathy with proximal weakness, chest pain, and increased serum creatine kinase (1710 U/L) and troponin levels (616 pg/mL). ECG remained stable with sinus rhythm, flattened T waves in apical and lateral regions, and frequent ventricular extrasystoles (Figure 2A and 2B). Cardiac ultrasonography disclosed mild global hypokinesia predominating in anterior and septal territories with 40% left ventricular ejection fraction (Movies II and III in the online-only Data Supplement) associated with septal thickening and infiltration ( Figure 3A and 3B) and transmural infiltration of anteroseptal wall ( Figure 3C). CMR showed severe global hypokinesia with 23% left ventricular ejection fraction (Movie IV), with an early and late transmural gadolinium enhancement of the anterolateral and anteroseptal walls ( Figure 4A and 4B and Movie V in the online-only Data Supplement), associated with circumferential subendocardial enhancement and pericardial effusion ( Figure 3C). Combination therapy with rituximab, prednisone, and methotrexate was reintroduced, with an improvement of muscle proximal weakness and the normalization of creatine kinase (145 U/L) and troponine (<14 pg/mL) levels.Cardiac involvement is recognized as a major clinical manifestation and 1 of the most frequent causes of death in patients with inflammatory or necrotizing myopathies, although its actual frequency is still uncertain, ranging from B, Classic indirect immunofluorescence assay on HEp-2 cells in the serum showed a characteristic cytoplasmic staining pattern. Dot-blot analysis of the serum showed specific reactivity against the signal recognition particle (SRP).