Van Leeuwen Peter, Hailer Birgit, Lange Silke, Grönemeyer Dietrich
Department of Biomagnetism, Research and Development Center for Microtherapy (EFMT), Bochum, Germany.
Pacing Clin Electrophysiol. 2003 Aug;26(8):1706-14. doi: 10.1046/j.1460-9592.2003.t01-1-00256.x.
The potential clinical value of QT dispersion (QTd), a measure of the interlead range of QT interval duration in the surface 12-lead ECG, remains ambiguous. The aim of the study was the temporal and spatial analysis of the QT interval in healthy subjects and in patients with coronary artery disease (CAD) using magnetocardiography (MCG) and surface ECG. Standard 12-lead ECG and 37-channel MCG were performed in 20 healthy subjects, 23 patients with CAD without prior myocardial infarction (MI), 31 MI patients and 11 MI patients with ventricular tachycardia (VT). QTd was increased in CAD without MI compared to normals (ECG 46.1 +/- 6.0 vs 42.8 +/- 5.0, P < 0.05; MCG 66.8 +/- 20.3 vs 49.7 +/- 10.8, P < 0.01) and in VT compared to MI (ECG 66.8 +/- 16.5 vs 51.9 +/- 16.6, P < 0.05; MCG 93.6 +/- 29.6 vs 66.8 +/- 20.8, P < 0.005). In MCG, spatial distribution of QT intervals in patient groups differed from those in healthy subjects in three ways: (1) greater dispersion, (2) greater local variability, and (3) a change in overall pattern. This was quantified on the basis of smoothness indexes (SI). Normalized SI was higher in CAD without MI compared to normals (3.8 +/- 1.1 vs 2.7 +/- 0.6, P < 0.001) and in VT compared to MI (6.4 +/- 1.6 vs 4.2 +/- 1.4, P < 0.0005). For the normal-CAD comparison a sensitivity of 74% and a specificity of 80% was obtained, for MI-VT, 100% and 77%, respectively. The results suggest that examining the spatial interlead variability in multichannel MCG may aid in the initial identification of CAD patients with unimpaired left ventricular function and the identification of post-MI patients with augmented risk for VT.
QT离散度（QTd）是体表12导联心电图中QT间期持续时间的导联间范围的一种测量指标，其潜在的临床价值仍不明确。本研究的目的是使用磁心动图（MCG）和体表心电图对健康受试者和冠心病（CAD）患者的QT间期进行时间和空间分析。对20名健康受试者、23名无既往心肌梗死（MI）的CAD患者、31名MI患者和11名伴有室性心动过速（VT）的MI患者进行了标准12导联心电图和37通道MCG检查。与正常受试者相比，无MI的CAD患者的QTd增加（心电图：46.1±6.0 vs 42.8±5.0，P<0.05；MCG：66.8±20.3 vs 49.7±10.8，P<0.01）；与MI患者相比，VT患者的QTd增加（心电图：66.8±16.5 vs 51.9±16.6，P<0.05；MCG：93.6±29.6 vs 66.8±20.8，P<0.005）。在MCG中，患者组QT间期的空间分布与健康受试者的QT间期空间分布在三个方面存在差异：（1）离散度更大；（2）局部变异性更大；（3）总体模式改变。这是根据平滑指数（SI）进行量化的。与正常受试者相比，无MI的CAD患者的标准化SI更高（3.8±1.1 vs 2.7±0.6，P<0.001）；与MI患者相比，VT患者的标准化SI更高（6.4±1.6 vs 4.2±1.4，P<0.0005）。对于正常与CAD的比较，敏感性为74%，特异性为80%；对于MI与VT的比较，敏感性和特异性分别为100%和77%。结果表明，检查多通道MCG中的导联间空间变异性可能有助于初步识别左心室功能未受损的CAD患者以及识别MI后发生VT风险增加的患者。
