Key result
The QT interval corrected for heart rate prolongation at maximal tachycardia after brisk standing in healthy prepubertal children was 79 ± 26 ms, significantly longer than in adults (50 ± 30 ms).
Why the study?
Does the brisk-standing-test result in different QTc prolongation in healthy prepubertal children compared to adults?
Cross-Sectional (n=57)
Blinded outcome assessment
No
Does the brisk-standing-test result in different QTc prolongation in healthy prepubertal children compared to adults?
Absolute Event Rate: 79% vs 50%
p-value: p=<0.001
Healthy prepubertal children exhibit significantly greater QTc prolongation during the brisk-standing-test compared to adults, necessitating age-specific cut-offs to avoid over-diagnosing long QT syndrome.
Pediatric QTc thresholds may be needed for the brisk-standing test; leaves open prospective validation before changing diagnostic criteria.
Aims: Long QT syndrome (LQTS) is associated with malignant arrhythmias and sudden death from birth to advanced age. Prolongation of the QT-interval, may however be concealed on standard electrocardiograms (ECG). The brisk-standing-test (BST) was developed to guide LQTS-diagnosis and treatment in adults. We hypothesized that the BST may be used in prepubertal children to identify LQTS subjects. Accordingly, reference values for the BST should be available to prevent incorrect diagnosis and treatment of LQTS. In this study, we aim to present reference values for prepubertal children. Methods and results: Healthy, prepubertal children, aged 7-13 years underwent a standard supine resting ECG and during continuous ECG recording performed a BST. The QT-interval and heart rate corrected QTc were measured during the different BST stages. Fifty-seven children, 29 boys (10.2 ± 1.1 years) and 28 girls (9.9 ± 1.1 years) were included. Baseline characteristics and response to standing were not statistically different for boys and girls: mean supine pre-standing heart rate 74 ± 9 vs. 77 ± 9 bpm, supine pre-standing QTc 406 ± 27 vs. 407 ± 17 ms, maximal heart rate upon standing 109 ± 11 vs. 112 ± 11 bpm, and QTc at maximal heart rate 484 ± 29 vs. 487 ± 35 ms. The QT interval corrected for heart rate-prolongation at maximal tachycardia after standing was 79 ± 26 (19-144) ms, which is significantly longer than previously published values in adults (50± 30 ms). Conclusions: The QT interval corrected for heart rate prolongation after brisk standing in healthy prepubertal children is more pronounced than in healthy adults. This finding advocates distinct prepubertal cut-off values because using adult values for prepubertal children would yield false positive results with the risk of incorrect LQTS-diagnosis and overtreatment.
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Filippini et al. (2017) conducted a cross-sectional in Healthy (reference values for Long QT syndrome) (n=57). Brisk-standing-test vs. Healthy adults (historical data) was evaluated on QTc prolongation at maximal tachycardia after standing (p=<0.001). The QT interval corrected for heart rate prolongation at maximal tachycardia after brisk standing in healthy prepubertal children was 79 ± 26 ms, significantly longer than in adults (50 ± 30 ms).
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