Enrique Calvo-Ayala is an attending physician, Division of Pulmonary, Critical Care and Sleep Medicine, William Beaumont Hospital, Royal Oak, Michigan and an assistant professor, Department of Internal Medicine, Oakland University William Beaumont School of Medicine, Rochester, Michigan.
Vince Procopio is a critical care pharmacy specialist, Department of Pharmacy, Henry Ford Macomb Hospital, Clinton Township, Michigan.
Am J Crit Care. 2021 Nov 1;30(6):466-470. doi: 10.4037/ajcc2021568.
QT prolongation increases the risk of ventricular arrhythmia and is common among critically ill patients. The gold standard for QT measurement is electrocardiography. Automated measurement of corrected QT (QTc) by cardiac telemetry has been developed, but this method has not been compared with electrocardiography in critically ill patients.
To compare the diagnostic performance of QTc values obtained with cardiac telemetry versus electrocardiography.
This prospective observational study included patients admitted to intensive care who had an electrocardiogram ordered simultaneously with cardiac telemetry. Demographic data and QTc determined by electrocardiography and telemetry were recorded. Bland-Altman analysis was done, and correlation coefficient and receiver operating characteristic (ROC) coefficient were calculated.
Fifty-one data points were obtained from 43 patients (65% men). Bland-Altman analysis revealed poor agreement between telemetry and electrocardiography and evidence of fixed and proportional bias. Area under the ROC curve for QTc determined by telemetry was 0.9 (P < .001) for a definition of prolonged QT as QTc ≥ 450 milliseconds in electrocardiography (sensitivity, 88.89%; specificity, 83.33%; cutoff of 464 milliseconds used). Correlation between the 2 methods was only moderate (r = 0.6, P < .001).
QTc determination by telemetry has poor agreement and moderate correlation with electrocardiography. However, telemetry has an acceptable area under the curve in ROC analysis with tolerable sensitivity and specificity depending on the cutoff used to define prolonged QT. Cardiac telemetry should be used with caution in critically ill patients.
QT 延长会增加室性心律失常的风险，在危重症患者中较为常见。QT 测量的金标准是心电图。已经开发出了通过心脏遥测技术自动测量校正 QT（QTc）的方法，但这种方法尚未在危重症患者中与心电图进行比较。
比较心脏遥测与心电图测量 QTc 值的诊断性能。
这项前瞻性观察性研究纳入了同时接受心电图和心脏遥测检查的重症监护病房患者。记录了人口统计学数据和心电图及遥测确定的 QTc 值。进行了 Bland-Altman 分析，并计算了相关系数和受试者工作特征（ROC）系数。
从 43 名患者（65%为男性）中获得了 51 个数据点。Bland-Altman 分析显示，遥测与心电图之间的一致性较差，且存在固定和比例偏差的证据。以心电图 QTc≥450 毫秒（敏感性为 88.89%，特异性为 83.33%，使用的截断值为 464 毫秒）定义 QT 延长时，遥测确定的 QTc 值的 ROC 曲线下面积为 0.9（P<0.001）。两种方法之间的相关性仅为中度（r=0.6，P<0.001）。
遥测确定的 QTc 值与心电图的一致性较差，相关性也较差。然而，遥测在 ROC 分析中具有可接受的曲线下面积，其敏感性和特异性取决于用于定义 QT 延长的截断值。在危重症患者中应谨慎使用心脏遥测。
