QTc Interval Prolongation and Its Association With Electrolyte Abnormalities and Psychotropic Drug Use Among Patients...

Eating disorders (EDs) often develop during adolescence with high mortality rates. Sudden cardiac death in these patients has been associated with corrected QT (QTc) interval prolongation. The significance of extrinsic factors on QTc prolongation in populations with EDs remains controversial. This study assessed the relationship between QTc prolongation in paediatric patients with EDs and extrinsic factors, such as QTc-prolonging medications and electrolyte abnormalities to investigate whether an ED alone is associated with an increased prevalence of QTc prolongation.

Electrocardiograms, electrolytes, and psychopharmaceutical usage were retrospectively analysed from the charts of 264 paediatric patients with EDs. Descriptive statistics were used to assess QTc prolongation and its relationship with electrolyte abnormalities and psychopharmaceuticals.

Of 264 patients, 227 had normal QTc intervals (<440 ms), whereas 37 had borderline prolonged (440-460 ms) or prolonged (>460 ms) intervals. The prevalence of QTc intervals exceeding 440 ms in patients with normal electrolytes and not using QTc-prolonging psychotropics mirrored that of the general population (P = 0.59). Of the 23 patients taking psychotropics, 8 had abnormal QTc intervals. The average QTc was greater for patients using QTc-prolonging psychotropics (P = 0.05) with a correlation between interval length and psychotropic usage (P < 0.01). Average potassium (P = 0.08), calcium (P = 0.18), and magnesium (P = 0.08) levels did not significantly differ between those with normal and abnormal QTc intervals.

This study suggests that EDs alone may not prolong QTc intervals in paediatric patients with EDs, but psychotropics appear to be a salient external factor in QTc prolongation.