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Effect of DKA on QTc Prolongation in Children Might Be Mediated by Ketosis, Not Electrolyte Abnormalities

Possible cardiac effects of ketosis make cardiac monitoring of children with DKA essential.

Ketotic conditions have been shown to be associated with prolonged QTc interval and sudden cardiac death. In an observational study, researchers examined whether QTc prolongation occurs during diabetic ketoacidosis (DKA) in children and whether it resolves when ketosis clears.

A convenience sample of 30 children (mean age, 11 years; 12% male) with DKA and not other risks for prolonged QTc interval underwent electrocardiography during DKA and after recovery. Patients were treated according to a standardized DKA protocol that included normal saline, insulin, glucose, and electrolyte replacement. A pediatric cardiologist who was blinded to clinical and biochemical data measured QTc intervals; measurements by a second cardiologist showed high interobserver agreement (=0.62). Prolonged QTc was defined as an interval of at least 450 milliseconds.

Initial electrocardiogram measurements were taken at a mean of 6 hours after initiation of DKA treatment. The QTc interval was significantly longer during DKA (mean, 450 ms; range, 378–539 ms) than after recovery (mean, 407 ms; range, 302–485 ms). Overall, QTc intervals were longer than 450 milliseconds in 47% of patients during DKA and in 13% after recovery; the interval eventually normalized in two of the four patients who continued to have prolonged intervals after recovery. At presentation, the anion gap was significantly higher in patients with QTc prolongation than in those without (27 vs. 22 mEq/L). QTc duration was significantly correlated with the anion gap during DKA but not with serum potassium, calcium, or magnesium values or heart rate.

Comment: Although no life-threatening arrhythmias were observed in this study, QTc prolongation can predispose to them. This study’s findings suggest that QTc prolongation in children with diabetic ketosis might occur even in the absence of significant electrolyte disturbances. Given the high incidence of QTc prolongation in children with DKA, cardiac monitoring is advisable until ketosis is clearly resolving.

— Jill M. Baren, MD, MBE, FACEP, FAAP

Published in Journal Watch Emergency Medicine July 25, 2008

Citation(s):

Kuppermann N et al. Prolonged QT interval corrected for heart rate during diabetic ketoacidosis in children. Arch Pediatr Adolesc Med 2008 Jun; 162:544.

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