Determinants of severe bradycardia in adolescents hospitalized for anorexia nervosa

Background: Severe bradycardia is an indication supporting hospitalization in adolescents with eating disorders. Some adolescents with anorexia nervosa (AN) and significant weight loss present with a normal pulse rate at admission, whereas others have severe bradycardia, suggesting that total weight loss is not the most important determinant of bradycardia. The aims of this study were to define the prevalence of severe bradycardia as the cause for hospital admission in adolescents with AN, to evaluate correlations between known determinants of severe bradycardia and pulse rate at admission, and to evaluate the average time required to recover from severe bradycardia after re-feeding. Methods: Ninety-nine hospitalized patients with AN were enrolled. Weight loss history, anthropometric, laboratory, and electrocardiogram data were collected at admission to and at discharge from hospital. Multivariate analysis was performed to detect the most important determinants of severe bradycardia. Results: Forty-eight percent of the AN patient admissions were due to severe bradycardia (AN-B+ group). Patients in this group had a higher maximum lifetime weight (P = 0.0045), greater premorbid weight loss (P = 0.0011), and more rapid weight loss (P = 0.0001). Multivariate analysis showed that recent weight loss is an independent predictor of bradycardia at hospital admission (R2: 0.35, P = 0.0001). Severe bradycardia normalized after minimal weight gain of 0.25 ± 0.18 kg/day for 3–10 days. Conclusions: This study confirms that recent weight loss is probably the most important determinant of severe bradycardia in adolescents with AN.