Pediatric Cardiology

, Volume 36, Issue 7, pp 1350–1356 | Cite as

Phenotype of Children with QT Prolongation Identified Using an Institution-Wide QT Alert System

  • Heather N. Anderson
  • J. Martijn Bos
  • Kristina H. Haugaa
  • Bruce W. Morlan
  • Robert F. Tarrell
  • Pedro J. Caraballo
  • Michael J. AckermanEmail author
Original Article


QT prolongation is an independent risk factor for cardiovascular mortality in adults. However, there is little information available on pediatric patients with QT prolongation and their outcomes. Herein, we evaluated the prevalence of QT prolongation in pediatric patients identified by an institution-wide QT alert system, and the spectrum of their phenotype. Patients with documented QT prolongation on an ECG obtained between November 2010 and June 2011 were included. There were 1303 pediatric ECGs, and 68 children had electrographically isolated QT prolongation. Comprehensive review of medical records was performed with particular attention to QT-prolonging clinical, laboratory, and medication data, which were summarized into a pro-QTc score. Overall, 68 (5 %) pediatric patients had isolated QT prolongation. The mean age of this pediatric cohort was 9 ± 6 years, and the average QTc was 494 ± 42 ms. All children had 1 or more QT-prolonging risk factor(s), most commonly QT-prolonging medications. One patient was identified with congenital long QT syndrome (LQTS), which was not previously diagnosed. In one-year follow-up, only one pediatric death (non-cardiac) occurred (1.5 %). Potentially QT-offending/pro-arrhythmic medications were changed in 80 % of pediatric patients after the physician received the QT alert. Children with QT prolongation had very low mortality and minimal polypharmacy. Still, medications and other modifiable conditions were the most common causes of QT prolongation. Children with a prolonged QTc should be evaluated for modifiable QT-prolonging factors. However, if no risk factors are present or the QTc does not attenuate after risk factor modification/removal, the child should be evaluated for congenital LQTS.


Long QT syndrome Mortality QT prolongation Risk factor Monitoring 





Long QT syndrome



This work was supported by the Mayo Clinic Windland Smith Rice Comprehensive Sudden Cardiac Death Program.

Ethical standard

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Conflict of interest

Dr. Ackerman is a consultant for Boston Scientific, Gilead Sciences, Medtronic, and St. Jude Medical. Dr. Ackerman and Mayo Clinic receive royalties from Transgenomic’s FAMILION-LQTS and FAMILION-CPVT genetic tests. The other authors have no conflicts of interest to disclose. None of the disclosures pertain to this study, and none of the companies provided financial support for this study.


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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • Heather N. Anderson
    • 1
  • J. Martijn Bos
    • 1
    • 2
    • 3
  • Kristina H. Haugaa
    • 2
  • Bruce W. Morlan
    • 4
  • Robert F. Tarrell
    • 5
  • Pedro J. Caraballo
    • 6
  • Michael J. Ackerman
    • 1
    • 2
    • 3
    Email author
  1. 1.Department of Pediatric and Adolescent Medicine/Division of Pediatric CardiologyMayo ClinicRochesterUSA
  2. 2.Department of Molecular Pharmacology and Experimental Therapeutics/Windland Smith Rice Sudden Death Genomics LaboratoryMayo ClinicRochesterUSA
  3. 3.Department of Internal Medicine/Division of Cardiovascular DiseasesMayo ClinicRochesterUSA
  4. 4.Department of Health Care Policy and ResearchMayo ClinicRochesterUSA
  5. 5.Department of StatisticsMayo ClinicRochesterUSA
  6. 6.Department of Internal Medicine, Division of General Internal MedicineMayo ClinicRochesterUSA

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