From the Department of Emergency Medicine, Sidra Medical and Research Center.
Division of Pediatric Emergency Medicine, Qatar Hamad General Hospital, Doha, Qatar.
Pediatr Emerg Care. 2020 Jun;36(6):286-290. doi: 10.1097/PEC.0000000000002125.
QTc interval is significant because prolongation may lead to ventricular dysrhythmia. Computerized electrocardiogram machines typically measure QT interval length and, using an algorithm assessment of multiple leads, calculate a QTc value. Manual measurement of the QT interval used to calculate the QTc value is more time-consuming but potentially more accurate. In this study, we compare the automated QTc calculation with the QTc value calculated using manual QT measurements.
We prospectively obtained 350 resting 12-lead electrocardiograms (ECGs) in children aged 2 to 14 years in an academic pediatric emergency department. Manual measurement of the QT interval was performed and the QTc was calculated using the 2 most commonly used correction methods, Bazzet and Fridericia formulas. The paired values were used to perform a Bland-Altman analysis and create a receiver operating characteristic curve.
Bland-Altman analysis determined that QT-automated and QTc-Bazett had an average difference of 3.8 milliseconds, with a standard deviation of 86 milliseconds (95% confidence interval = -161 to 176). An automated QTc value of 455 milliseconds was sensitive to detect manual QTc values of greater than 480 milliseconds.
In children with resting ECGs, there is a poor agreement between the automated QTc produced by a computerized electrocardiogram and the QTc value obtained using manual QT measurement. Statistically and clinically relevant discrepancy between the automated QTc and QTc values calculated after manual QT measurement was present. Automated QTc values may be used as a screening tool to detect prolonged QTc, but for accurate determination of QTc, manual measurement is necessary.
QTc 间期很重要，因为延长可能导致室性心律失常。计算机心电图机通常测量 QT 间期长度，并使用多导联算法评估来计算 QTc 值。手动测量 QT 间期用于计算 QTc 值虽然耗时，但可能更准确。本研究比较了自动 QTc 计算与手动 QT 测量计算的 QTc 值。
我们前瞻性地在学术儿科急诊部门获得了 350 例年龄在 2 至 14 岁的静息 12 导联心电图（ECG）。手动测量 QT 间期，并使用最常用的两种校正公式（Bazzett 和 Fridericia 公式）计算 QTc。使用配对值进行 Bland-Altman 分析并绘制受试者工作特征曲线。
Bland-Altman 分析确定 QT-自动和 QTc-Bazett 的平均差异为 3.8 毫秒，标准偏差为 86 毫秒（95%置信区间=-161 至 176）。自动 QTc 值为 455 毫秒时，可敏感地检测到手动 QTc 值大于 480 毫秒。
在静息 ECG 的儿童中，计算机心电图产生的自动 QTc 与手动 QT 测量获得的 QTc 值之间存在较差的一致性。自动 QTc 值与手动 QT 测量后计算的 QTc 值之间存在统计学和临床相关的差异。自动 QTc 值可作为检测延长 QTc 的筛查工具，但为了准确确定 QTc，需要手动测量。
