Antithymocyte Globuline Therapy and Bradycardia in Children

In antithymocyte globulin (ATG) treated patients occasionally bradycardia has been noticed. Therefore, we retrospectively analyzed the occurrence of bradycardia in ATG-treated children. Using medical records between 2007 and 2012 we identified children undergoing a combined therapy with ATG and glucocorticoids (ATG group, n = 22). The incidence of bradycardia was compared to that registered in children treated with glucocorticoids alone (glucocorticoid alone group, n = 21). Heart rates (HR) were registered before and on days 0–3, 4–7 and 8–14 after the ATG or steroid administration. The rate of bradycardic episodes was higher during ATG therapy than in the steroid alone group, while severe bradycardia occurred only in the ATG group (97 versus 32, p = 0.0037, and 13 versus 0, p = 0.0029, respectively). There was an interaction between the time and treatment group on HR (p = 0.046). Heart rates in ATG and steroid alone groups differed significantly on day 0–3 and day 4–7 (p = 0.046, p = 0.006, respectively). Within the ATG group HR was lower on days 4–7 compared to the days before and the days 8–14 values (p < 0.001, 95%CI: 0.020–0.074). These findings indicate that transient asymptomatic bradycardia is probably more common with ATG therapy than previously reported. HR should be closely monitored during and after ATG therapy.