Key result
The QT variability index is significantly correlated with autonomic nerve balance in healthy children, showing a positive correlation with the LF/HF ratio (r = 0.45) and a negative correlation with the HF/(LF + HF) ratio (r = -0.429).
Why the study?
Although frequency analysis of heart rate variability detects autonomic balance, it was unclear whether QT variability index correlates with autonomic nerve activity in children.
Cross-Sectional (n=320)
No
Effect estimate: r = 0.45
p-value: p=<0.001
QTVI calculated from a short-term ECG significantly correlates with HRV parameters, suggesting it can serve as a non-invasive marker of autonomic nerve balance in healthy children.
May indicate autonomic imbalance via QTVI in children; hypothesis-generating and requires prospective validation before clinical use.
The QT variability index (QTVI), which measures the instability of myocardial repolarization, is usually calculated from a single electrocardiogram (ECG) recording and can be easily applied in children. It is well known that frequency analysis of heart rate variability (HRV) can detect autonomic balance, but it is not clear whether QTVI is correlated with autonomic tone. Therefore, we evaluated the association between QTVI and HRV to elucidate whether QTVI is correlated with autonomic nerve activity. Apparently, healthy 320 children aged 0-7 years who visited Fujita Health University Hospital for heart checkup examinations were included. The RR and QT intervals of 60 continuous heart beats were measured, and the QTVI was calculated using the formula of Berger et al. Frequency analysis of HRV, including the QTVI analysis region, was conducted for 2 min and the ratio of low-frequency (LF) components to high-frequency (HF) components (LF/HF) and HF/(LF + HF) ratio was calculated as indicators of autonomic nerve activity. Then, the correlations between QTVI and these parameters were assessed. QTVI showed a significant positive correlation with LF/HF ratio (r = 0.45, p < 0.001) and negative correlation with HF/(LF + HF) ratio (r = -0.429, p < 0.001). These correlations remained after adjustment for sex and age. QTVI, which is calculated from non-invasive ECG and can detect abnormal myocardial repolarization, is significantly correlated with frequency analysis of HRV parameters. QTVI reflects autonomic nerve balance in children.
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Kusuki et al. (2020) conducted a cross-sectional in Healthy children (n=320). QT variability index (QTVI) was evaluated on Correlation between QTVI and LF/HF ratio (r = 0.45, p=<0.001). The QT variability index is significantly correlated with autonomic nerve balance in healthy children, showing a positive correlation with the LF/HF ratio (r = 0.45) and a negative correlation with the HF/(LF + HF) ratio (r = -0.429).
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