Second degree atrioventricular block in mixed connective tissue disease

Mixed connective tissue disease (MCTD) is characterized by overlapping features of progressive systemic sclerosis, dermatomyositis and systemic lupus erythematosus, and by high rate of antibodies to an extractable nuclear antigen ribonucleoprotein. Cardiac manifestations in MTCD are rare. A 58 years old man was admitted for mild fever, a impairment of the general status, muscular pain and a Raynaud's phenomenon. Biologic abnormalities were an inflammatory syndrome, elevated serum CPK and high rate anti-RNP antibodies. Diagnosis of mixed connective tissue disease was made. Shortly after, a Wenckebach atrioventricular block occurred. Systemic corticosteroids were efficient. Heart blocks are rarely described in MCTD. Three cases have been reported. It's a systemic complication resulting of an inflammatory process often responsive to steroids.