Alqarawi Wael, Allwaim Marwah
Department of Cardiac Sciences, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
Front Cardiovasc Med. 2024 Oct 10;11:1465264. doi: 10.3389/fcvm.2024.1465264. eCollection 2024.
Corrected QT (QTc) is an important electrocardiographic (ECG) interval. Physicians rely on automated QTc provided by ECG machines while the manual method is the recommended method. We sought to assess the prevalence and predictors of false positive QTc prolongation by the automated measurement.
Consecutive ECGs were retrieved from the ECG database at King Khaled University Hospital. Manual QT was measured by a trained physician using the tangent method and was corrected for heart rate and QRS duration. Automated QTc measurement was recorded by the ECG machine. "Long QT (LQT)" was defined as QTc≥470 ms for males and ≥480 for females. False positive LQT was defined as LQT by automated QTc but not manual QTc. Pre-determined factors were included in a multivariate logistic regression to assess predictors of false positive LQT. A total of 567 ECGs were included in this study. Automated QTc was longer than manual QTc (440 ms [±35] vs. 417 ms [±35], respectively) which resulted in a high negative predictive value (NPV) (99%) and a low positive predictive value (PPV) (32%). Male gender and abnormal rhythm were found to be independently associated with false positive LQT (OR = 1.9 [95% 1.1-3.5], = 0.03 and OR = 3.1 [95% 1.2-8.3], = 0.02; respectively).
Automated QTc measurement is unreliable for detecting long QT, necessitating manual verification and further research to enhance its accuracy.
校正QT（QTc）是一项重要的心电图（ECG）间期。医生依赖心电图机提供的自动QTc测量值，而手动测量方法是推荐方法。我们旨在评估自动测量导致QTc延长假阳性的患病率及预测因素。
从哈立德国王大学医院的心电图数据库中检索连续的心电图。由一名经过培训的医生使用切线法测量手动QT，并针对心率和QRS波时限进行校正。心电图机记录自动QTc测量值。“长QT（LQT）”定义为男性QTc≥470毫秒，女性≥480毫秒。假阳性LQT定义为自动QTc测量显示为LQT，但手动QTc测量并非如此。将预先确定的因素纳入多因素逻辑回归，以评估假阳性LQT的预测因素。本研究共纳入567份心电图。自动QTc长于手动QTc（分别为440毫秒[±35]和417毫秒[±35]），这导致了较高的阴性预测值（NPV）（99%）和较低的阳性预测值（PPV）（32%）。发现男性性别和异常心律与假阳性LQT独立相关（OR = 1.9[95% 1.1 - 3.5]，P = 0.03；OR = 3.1[95% 1.2 - 8.3]，P = 0.02）。
自动QTc测量对于检测长QT不可靠，需要进行手动验证并开展进一步研究以提高其准确性。
