Abstract 11657: Frequency and Severity of Hypoglycemia in Children With Beta Blocker-Treated Long QT Syndrome
Background: Beta-blockers are the treatment of choice for most children with long QT syndrome (LQTS). Hypoglycemia is a known adverse effect of beta-blocker therapy, however, only a few such cases have been reported in the literature in pediatric patients. Here, we determined the frequency and severity of hypoglycemia among children with beta-blocker treated LQTS.
Methods: A retrospective electronic medical record review identified 323 children with clinically/genetically diagnosed LQTS on beta-blocker therapy (157 males, average age at diagnosis 8 ± 5 years old, average QTc 470 ± 53 ms, LQT1 in 157, LQT2 in 105, and LQT3 in 13) who were evaluated in Mayo Clinic’s LQTS Clinic from 2000 - 2014.
Results: Overall, 10 children (3.1%; 7 males, average QTc 486 ± 35 ms) developed 12 episodes of hypoglycemia (mean initial glucose 19 ± 7 mg/dL) with beta-blocker associated hypoglycemic episodes in 6/105 LQT2 patients (5.7%) and 3/157 LQT1 patients (1.9%, p = 0.16). The mean age at hypoglycemia was 3.5 ± 2 years (range 7 months - 9 years) while taking nadolol in 7 (mean dose 1.4 ± 0.2 mg/kg/day) and propranolol in 3 (mean dose = 2.7 ± 1 mg/kg/day). Hypoglycemia-triggered seizures were observed in 6 subjects (nadolol n = 5, propranolol n=1) and fasting ketoacidosis in 5 (nadolol n = 5). There were no deaths but seven required hospitalization (mean of 3 ± 2 days). All patients recovered without any neurologic sequelae and two patients experienced a second episode of hypoglycemia. Decreased caloric intake the evening prior was identified in all patients and a concomitant viral infection in 3. Complete metabolic work-up was performed (5) for which one patient, a 5.7 year old male/with LQT1, was diagnosed with a glycogen synthase deficiency disease unmasked by non-selective beta-blockade.
Conclusion: This is the largest reported case series of hypoglycemia in beta-blocker treated children with LQTS. Although uncommon (3%), parents of young children with LQTS should be educated on the signs and symptoms of hypoglycemia and should be especially cognizant of these symptoms during periods of poor appetite and during viral illness. Considering the emerging role of the KCNH2-encoded Kv11.1 channel in insulin secretion, a potential LQT2-hypoglycemia relationship warrants further investigation.
Author Disclosures: J.T. Poterucha: None. J.M. Bos: None. B.C. Cannon: Consultant/Advisory Board; Modest; Medtronic. M.J. Ackerman: Consultant/Advisory Board; Modest; Boston Scientific, Gilead Sciences, Medtronic, and St. Jude Medical. Other; Significant; Intellectual Property/Royalties (Significant): Transgenomic..
- © 2014 by American Heart Association, Inc.