Thyroid Hormone (Triiodothyronine) Therapy in Children After Congenital Heart Surgery: A Meta-Analysis

Thyroid hormone modifies metabolic, immune and cardiovascular functions and has been administered perioperatively to treat a relative reduction of thyroid function in children following cardiopulmonary bypass (CPB) for correction of congenital heart disease. However, it remains unclear whether its use is associated with improved outcomes. We performed a meta-analysis of studies that evaluated the impact of thyroid hormone supplementation on clinical outcomes in children undergoing repair of congenital heart disease using CPB. A systematic review of published trials was conducted to identify studies of children randomized to thyroid hormone supplementation or placebo undergoing congenital heart surgery. A meta-analysis was then conducted to determine the clinical impact of thyroid hormone replacement on cardiac function and postoperative characteristics. The following outcomes were included for the study: duration of mechanical ventilation, duration of intensive care unit (ICU) stay, duration of postoperative hospital stay, inotrope score, cardiac index at 24 hours postoperatively, and inpatient mortality. A total of 9 studies with 711 patients were included in the analyses. All included studies were prospective and patients were randomized to either thyroid hormone or placebo. There was wide variation in thyroid hormone dosing, ranging from 0.4 μg/kg up to 5 μg/kg over a 24-hour period, and duration of therapy, ranging from a single dose after cessation of CPB to continued thyroid hormone for the duration of the ICU stay. There was a significant difference in the mean inotrope score between the 2 groups of -1.249 (95% confidence interval -1.570 to -0.929, P < 0.001), with the inotrope score being significantly lower in the thyroid group. There was no difference in duration of mechanical ventilation, duration of ICU stay, duration of hospital stay, cardiac index, and mortality between groups. In this meta-analysis, routine thyroid hormone replacement with approximately 1-5 μg/kg administered over 24 hours does not significantly alter the postoperative course in children following CPB. However, given a clinically small but significant difference in respect to lower inotrope score and shorter duration of ICU and hospital stays with higher thyroid replacement additional studies are warranted.