Tentative Screening Criteria for Short QT Interval in Children and Adolescents.

Background: While the prevalence of short QT syndrome (SQTS) in children and adolescents is low, early detection is important because SQTS can cause life-threatening arrhythmia. The aim of this study was to determine the tentative screening criteria for short QT interval in children and adolescents.

Methods and results: A total of 75,040 digitally stored electrocardiograms (ECG) of participants in a school-based ECG screening program were obtained between 2009 and 2013 in Kagoshima, Japan. ECG with a corrected QT interval (QTc) below the 10th percentile for each grade and sex were selected: 2,581 first graders (M/F, 1,296/1,285); 2,792 7th graders (M/F, 1,400/1,392); and 2018 10th graders (M/F, 979/1,039). Three consecutive QT/RR intervals were manually measured and corrected using Bazett's formula. The prevalence of SQTS was estimated at 1/30,000-1/10,000, which was set compared with the prevalence of long QT syndrome, then the screening points of the prevalence of short QT interval were assumed to be between 1/5,000 and 1/2,000 to exclude the possibility of false negative. We obtained the following tentative criteria based on frequency distribution charts: 325, 315 and 305 ms for male 1st, 7th and 10th graders, respectively; and 320 ms for female 1st, 7th, and 10th graders.

Conclusions: For primary SQTS screening of children and adolescents, the QTc values for short QT interval should be adapted according to grade and sex.