Adult acute rheumatic fever: a rare case presenting with left bundle branch block.

In contrast to the more common electrocardiographic patterns seen in acute rheumatic fever, such as first-degree heart block, the appearance of left bundle branch block is rare. An adult patient with acute rheumatic fever presented with left bundle branch block on admission, subsequently had sudden cardiac arrest. She was resuscitated successfully and required temporary pacing. An echocardiogram and radionuclide ventriculography were compatible with interventricular septal involvement in the rheumatic carditis. After 20 days of steroid therapy, the left bundle branch block pattern of the electrocardiogram disappeared. A possible mechanism for the development of complete heart block in acute rheumatic fever is discussed. It is suggested that patients with acute rheumatic carditis who have electrocardiographic manifestations of prolonged P-R interval and left bundle branch block should be managed with prophylactic pacing.