Viitasalo Matti, Oikarinen Lasse, Väänänen Heikki, Swan Heikki, Piippo Kirsi, Kontula Kimmo, Barron Hal V, Toivonen Lauri, Scheinman Melvin M
Department of Medicine, Cardiac Electrophysiology, University of California, San Francisco, San Francisco, California, USA.
Am J Cardiol. 2002 Mar 15;89(6):679-85. doi: 10.1016/s0002-9149(01)02339-6.
This study assesses the use of 24-hour ambulatory electrocardiographic recordings in distinguishing patients with long-QT1 syndrome (LQT1) from those with LQT2, and for distinguishing affected from unaffected patients. The diagnoses of the congenital LQT syndrome and its most common types LQT1 and LQT2 are made difficult because of the limitations of the electrocardiogram as a diagnostic tool. With an automated computerized program, Holter recordings from 15 LQT1 and 15 LQT2 patients and 43 healthy subjects (training set) were reviewed to select the best criteria using QT duration and rate dependence as well as the difference between QT end and QT apex to separate the 3 groups. Fixed criteria were then applied in blinded fashion to separate a different group of 32 genotyped patients and 16 unaffected subjects (test set). In the training set, the RR interval (100 ms), a slope value for median QT/RR curves of -0.016 separated 25 of 30 (83%) and a minimal QT end - QT apex value of 80 ms, separated 26 of 30 (87%) LQT1 patients from LQT2 patients. When all selected criteria were applied to differentiate LQT1 from LQT2 versus unaffected genotypes in the test set, 38 of 48 cases (79%) were correctly identified, whereas using the electrocardiogram alone, 60% of patients were correctly classified into 3 genotypes (p = 0.03). Combining measures for QT duration, rate dependence, and QT end - QT apex interval, derived from Holter recordings, complements the clinical differentiation between LQT1 versus LQT2 patients and between affected and unaffected persons for genotype screening purposes.
本研究评估了24小时动态心电图记录在区分长QT1综合征（LQT1）患者与LQT2患者，以及区分患病与未患病患者方面的应用。由于心电图作为诊断工具存在局限性，先天性长QT综合征及其最常见类型LQT1和LQT2的诊断较为困难。利用一个自动化计算机程序，对15例LQT1患者、15例LQT2患者和43名健康受试者（训练集）的动态心电图记录进行回顾，以选择使用QT间期、心率依赖性以及QT终点与QT顶点之间的差异来区分这三组的最佳标准。然后以盲法应用固定标准来区分另一组32例基因分型患者和16名未患病受试者（测试集）。在训练集中，RR间期（100毫秒）、中位数QT/RR曲线的斜率值-0.016可将30例中的25例（83%）LQT1患者与LQT2患者区分开，最小QT终点-QT顶点值80毫秒可将30例中的26例（87%）LQT1患者与LQT2患者区分开。当将所有选定标准应用于测试集以区分LQT1与LQT2以及未患病基因型时，48例中的38例（79%）被正确识别，而仅使用心电图时，60%的患者被正确分类为三种基因型（p = 0.03）。结合从动态心电图记录得出的QT间期、心率依赖性以及QT终点-QT顶点间期的测量方法，可补充LQT1与LQT2患者之间以及患病与未患病个体之间的临床鉴别，用于基因型筛查目的。
