Age and Gender Specific Criteria for Signal‐Averaged Electrocardiographic Parameters in Healthy Chinese Children

Background: Detection of late potentials (LPs) using signal‐averaged electrocardiograms (SAECGs) is believed to help in the prediction of malignant ventricular arrhythmias and sudden cardiac death in adults. Criteria for detection of LPs in adults may not be applicable for children, as these measurements are known to be age and sex specific. Method: SAECGs were recorded using MAC 15 ECG System. Duration of filtered QRS (TQRS), duration of high frequency, low amplitude signals in the terminal portion of QRS complex that are < 40 μV (HFLA), and root mean square voltage of the last 40 ms of the filtered QRS (RMS40) were determined for 535 healthy Chinese children, ages 6–17 years (268 males, 267 females). Results: Both mean TQRS and RMS40 were significantly different between the male and female children (TQRS: 106 ms vs 101 ms, P < 0.001; and RMS40: 62 μV vs 75 μV, P < 0.001). Mean TQRS and HFLA increased significantly with age, while mean RMS40 decreased with age (P < 0.0001). Ninetieth percentile values of TQRS and HFLA and tenth percentile value of RMS40 were used as cut‐off values for normal limits. As such, the criteria for normal TQRS, HFLA, and RMS4O were: TQRS < 117 ms; HFLA < 35 ms; and RMS40 >12 μV. Since TQRS and RMS40 were gender specific, the criteria for male and female were: TQRS: Male < 118 ms, female < 111 ms; and RMS40: Male >9 μV, female >17 μV. Conclusion: TQRS, HFLA, and RMS40 were shown to be age and sex specific in healthy Chinese children. The criteria for normal TQRS, HFLA and RMS40 were different from those proposed for adults, and this may be partly due to technical differences of the recording system.