Robyns Tomas, Nuyens Dieter, Vandenberk Bert, Haemers Peter, Breckpot Jeroen, Garweg Christophe, Ector Joris, Willems Rik
Department of Cardiovascular Diseases, University Hospitals Leuven, Leuven, Belgium.
Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
Front Cardiovasc Med. 2023 May 11;10:1097468. doi: 10.3389/fcvm.2023.1097468. eCollection 2023.
Diagnosis of Long QT syndrome (LQTS) is based on prolongation of the QT interval corrected for heart rate (QTc) on surface ECG and genotyping. However, up to 25% of genotype positive patients have a normal QTc interval. We recently showed that individualized QT interval (QTi) derived from 24 h holter data and defined as the QT value at the intersection of an RR interval of 1,000 ms with the linear regression line fitted through QT-RR data points of each individual patient was superior over QTc to predict mutation status in LQTS families. This study aimed to confirm the diagnostic value of QTi, fine-tune its cut-off value and evaluate intra-individual variability in patients with LQTS.
From the Telemetric and Holter ECG Warehouse, 201 recordings from control individuals and 393 recordings from 254 LQTS patients were analysed. Cut-off values were obtained from ROC curves and validated against an in house LQTS and control cohort.
ROC curves indicated very good discrimination between controls and LQTS patients with QTi, both in females (AUC 0.96) and males (AUC 0.97). Using a gender dependent cut-off of 445 ms in females and 430 ms in males, a sensitivity of 88% and specificity of 96% were achieved, which was confirmed in the validation cohort. No significant intra-individual variability in QTi was observed in 76 LQTS patients for whom at least two holter recordings were available (483 ± 36 ms vs. 489 ± 42 ms, = 0.11).
This study confirms our initial findings and supports the use of QTi in the evaluation of LQTS families. Using the novel gender dependent cut-off values, a high diagnostic accuracy was achieved.
长QT综合征（LQTS）的诊断基于体表心电图上校正心率后的QT间期（QTc）延长及基因分型。然而，高达25%的基因型阳性患者QTc间期正常。我们最近发现，从24小时动态心电图数据得出的个体化QT间期（QTi），定义为RR间期为1000毫秒时与通过每位患者QT-RR数据点拟合的线性回归线交点处的QT值，在预测LQTS家系的突变状态方面优于QTc。本研究旨在确认QTi的诊断价值，微调其临界值，并评估LQTS患者的个体内变异性。
分析了来自遥测和动态心电图数据库的201份对照个体记录以及254例LQTS患者的393份记录。从ROC曲线获得临界值，并在内部的LQTS和对照队列中进行验证。
ROC曲线表明，无论是女性（AUC 0.96）还是男性（AUC 0.97），QTi在对照个体和LQTS患者之间都有很好的区分度。使用女性445毫秒、男性430毫秒的性别依赖性临界值，敏感性为88%，特异性为96%，这在验证队列中得到了证实。在至少有两份动态心电图记录的76例LQTS患者中，未观察到QTi有显著的个体内变异性（483±36毫秒对489±42毫秒，P = 0.11）。
本研究证实了我们的初步发现，并支持在评估LQTS家系时使用QTi。使用新的性别依赖性临界值，可实现较高的诊断准确性。
