Circulation Journal
Online ISSN : 1347-4820
Print ISSN : 1346-9843
ISSN-L : 1346-9843
Pediatric Cardiology and Adult Congenital Heart Disease
Mid-Term Follow-up of School-Aged Children With Borderline Long QT Interval
Aya MiyazakiHeima SakaguchiYu MatsumuraYosuke HayamaKanae NoritakeJun NegishiEtsuko TsudaYoshihiro MiyamotoTakeshi AibaWataru ShimizuKengo KusanoIsao ShiraishiHideo Ohuchi
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2017 Volume 81 Issue 5 Pages 726-732


Background:There are no definitive diagnostic criteria or follow-up strategies for long QT syndrome (LQTS) in children with a borderline long QT interval (b-LQT).

Methods and Results:We retrospectively evaluated the clinical course, genetic testing results, corrected QT interval (QTc), and LQTS score of 59 school-aged children (5–18 years old) with a b-LQT (400≤QTc<500 ms). Syncope, but neither aborted cardiac arrest nor sudden cardiac death, occurred in 2 patients during the follow-up (6±3.4 years) with LQTS scores ≥4.5 points. The genetic testing results were positive in 92%, 57%, and 67% of patients with high, intermediate, and low probabilities of LQTS, respectively. The maximum and mean QTc during the follow-up significantly differed among the categories with a probability of LQTS, but not the minimum QTc. However, the QTc at rest and at the recovery point after exercise stress testing dramatically changed at the last follow-up. Consequently, the probability of LQTS changed in half of the patients.

Conclusions:The LQTS score is a reasonable indicator for evaluating school-aged children with a b-LQT, and patients with a low LQTS score appear to be at low risk for cardiac events. However, the LQTS score can change during follow-up. Therefore, when there is doubt or concern for patients with a b-LQT, it is preferable to continue following them. Guidelines on follow-up strategies are desired for b-LQT.

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