title: Reproducibility of corrected QT interval in pediatric genotyped long QT syndrome.
abstract: Reproducibility of corrected QT interval (QTc), especially QTc after exercise, has not been thoroughly investigated. We reviewed charts of pediatric patients who underwent treadmill-exercise stress testing without medication multiple times within 1 year. In patients with long-QT syndrome (LQTS; n = 22), the discrepancy in QTc between two treadmill exercise stress tests using Fridericia's formula was 14 ± 12 ms at rest, 13 ± 12 ms 4 min after exercise, with a maximum of 14 ± 12 ms after exercise. There was no statistically significant difference in QTc between the two tests. Intraclass correlation coefficients (ICC) were 0.84, 0.85, and 0.85, respectively. In controls (n = 13), the discrepancy in QTc was 18 ± 12 ms at rest, 14 ± 7 ms 4 min after exercise, with a maximum of 14 ± 9 ms after exercise. There was no significant difference in QTc between the two tests. ICC were 0.78, 0.80, and 0.80, respectively. QTc calculated using Bazett's formula also showed high reproducibility. Reproducibility of QTc in children is high at rest and after exercise.
authors.affiliation: Division of Cardiology, Kobe Children's Hospital, Kobe, Hyogo, Japan.
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Ogawa
authors.affiliation: Division of Cardiology, Kobe Children's Hospital, Kobe, Hyogo, Japan.
authors.forename: Toshikatsu
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Division of Cardiology, Kobe Children's Hospital, Kobe, Hyogo, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Kido
mesh_terms: D002648:Child; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D005838:Genotype; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D008297:Male; D015203:Reproducibility of Results; D012189:Retrospective Studies
keywords: Bazett's formula; Fridericia's formula; exercise stress test; long QT syndrome; reproducibility