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Comparison of formulas for calculation of the corrected QT interval in infants and young children

Derek Q Phan1, Michael J Silka2, Yueh-Tze Lan3

  • 1Division of Pediatric Cardiology, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles Medical Center, Torrance, CA.

The Journal of Pediatrics
|February 5, 2015
PubMed

Insights

The Bazett formula provides the most consistent rate-corrected QT (QTc) interval calculation in infants and children. A threshold of 460 ms is recommended for identifying prolonged QTc in this population.

Area of Science:

  • Pediatric Cardiology
  • Electrocardiography
  • Clinical Research

Background:

  • Accurate assessment of the rate-corrected QT (QTc) interval is crucial for pediatric cardiac health.
  • Several formulas exist for QTc calculation, but their consistency in infants and young children varies.

Purpose of the Study:

  • To compare the accuracy and consistency of four common QTc correction formulas (Bazett, Fridericia, Hodges, Framingham) in pediatric populations.
  • To determine the optimal QTc interval threshold for identifying prolonged QTc in infants and young children.

Main Methods:

  • Digital electrocardiograms from 702 children were analyzed.
  • QT and R-R intervals were measured to calculate QTc using Bazett, Fridericia, Hodges, and Framingham formulas.
  • QTc versus R-R regression line slopes were compared to assess formula consistency.

Main Results:

  • The Bazett formula demonstrated the most consistent QTc correction across heart rates (slope -0.019).
  • The Fridericia, Hodges, and Framingham formulas showed less consistent corrections.
  • A QTc threshold of 460 ms with the Bazett formula was identified as 2 standard deviations above the mean.

Conclusions:

  • The Bazett formula is the most reliable for QTc calculation in infants and children.
  • A QTc threshold of 460 ms is recommended for prolonged QTc in this age group.
  • Findings support the continued use of Bazett formula, contrasting with Fridericia's use in some clinical trials.
Abstract

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