A case report of Adult-onset Still's disease as a cause of severe mitral regurgitation

Background: Adult-onset Still's disease (AOSD) is an uncommon systemic inflammatory disease, causing spiking fever, skin rash, and arthritis. Pericarditis and myocarditis are the most common cardiac manifestation of AOSD but valvular involvement is rarely reported.

Case summary: An 18-year-old boy presented with gradually worsening shortness of breath for 6 months. There was a history of low-grade intermittent fever and polyarthralgia affecting ankles, knees, and elbows. He was in heart failure with cardiogenic and septic shock. He was managed initially with antibiotics, inotropes, and diuretics. Echocardiography showed flail anterior mitral leaflet with severe mitral regurgitation. He remained febrile with persistent negative blood cultures. Intravenous antibiotics led to neutropenia without any response to fever and clinical status. On further workup, he was diagnosed to have AOSD, and he responded dramatically to oral steroid therapy. Later his mitral valve was replaced surgically. On follow-up, he was stable with mild exertional dyspnoea. His international normalized ratio was in therapeutic range and his follow-up echocardiography showed normally functioning mitral prosthesis. He is following rheumatology and currently on the maintenance dose of steroids.

Discussion: Adult-onset Still's disease is a systemic illness with diagnosis is based on clinical features and exclusion of other illnesses. Adult-onset Still's disease should be considered as a differential diagnosis in culture-negative endocarditis, especially in those with systemic features and non-responders to antibiotics.