QT prolongation by isoproterenol in anorexia nervosa

A 17-year-old male with anorexia nervosa developed atypical prolongation of his corrected QT interval (QTc) when placed on isoproterenol for profound sinus bradycardia. His QTc normalized after the infusion was discontinued. Autonomic imbalance may explain the observed QTc lengthening. Because bradycardia associated with weight loss in anorexia is usually a physiologic adaptation and rarely symptomatic, aggressive chronotropic therapy may be not only unwarranted, but potentially deleterious.