Myocarditis in Adult-Onset Still Disease

This study highlights the clinical features, treatments, and outcomes of the rare myocarditis in adult-onset Still disease (AOSD). Among a case series of 57 patients fulfilling either Yamaguchi or Fautrel AOSD criteria and seen between 1998 and 2010, we identified 4 cases of myocarditis. From a comprehensive literature review, we collected 20 additional cases of myocarditis-complicated AOSD. The characteristics of patients with myocarditis were compared with those of AOSD patients without myocarditis.In these 24 myocarditis-complicated AOSD cases, myocarditis occurred early and was present at AOSD onset in 54% of the cases. Myocarditis was often symptomatic (96% of patients) with nonspecific electrocardiographic abnormalities (79% of patients) and a left ventricle ejection fraction ≤50% (67% of patients). Cardiac magnetic resonance imaging and endomyocardial biopsies showed features consistent with myocarditis in 4 patients and a mononuclear interstitial inflammatory infiltrate in 4 others. Steroids alone were effective in 50% of patients with myocarditis. Intravenous immunoglobulins, methotrexate, and tumor necrosis factor-α-blockers were also prescribed and often found effective. Only 1 patient died from cardiogenic shock. Patients with myocarditis-complicated AOSD were younger and more frequently male than patients with AOSD alone. Pericarditis was more frequent in the myocarditis group; white blood cell count, polymorphonuclear cell count, and serum ferritin levels were also higher.Myocarditis is a potentially life-threatening complication of AOSD but responds positively to steroids and other immunomodulatory drugs. Its prognosis remains good (only 1 death occurred), but the condition requires close monitoring of heart function.