Effects of Methadone on Corrected Q-T Interval Prolongation in Critically Ill Children.

Objectives: This study aimed to determine the association between methadone use and corrected Q-T interval (QTc) prolongation in critically ill children.

Methods: A retrospective cohort study of critically ill children receiving methadone at a tertiary care pediatric hospital was conducted. Patients younger than 19 years who had been admitted to the intensive care unit between January 1, 2009, and June 21, 2013, who had received methadone while inpatients, and who had had electrocardiograms (ECGs) performed within 30 days before and after methadone initiation were included. The primary outcome was the net change in QTc interval between baseline and postmethadone ECGs. Secondary outcomes included percent change in QTc interval and the proportion of patients whose QTc intervals changed from normal to prolonged following methadone initiation. We also evaluated potential predictors of QTc interval prolongation, including age, sex, admission diagnosis category, exposure to other QTc-prolonging medications, presence of congenital heart disease or known arrhythmias, and methadone daily dose and route of administration.

Results: Sixty-four patients met the inclusion criteria. The median (25th, 75th percentiles) change in QTc interval following methadone initiation was -8 msec (-34, 13.5 msec; p = 0.19). Five patients (8%) had a baseline normal QTc interval that became prolonged after methadone initiation. We identified no statistically significant predictors of QTc prolongation after methadone initiation.

Conclusions: In this dedicated pediatric safety study, methadone initiation did not result in prolongation of the QTc interval. Although these findings suggest methadone initiation may not have a substantial effect of QTc prolongation in critically ill children, a controlled, prospective evaluation in this population remains warranted.