Kasamaki Yuji, Ozawa Yukio, Ohta Masakatsu, Sezai Akira, Yamaki Takashi, Kaneko Mutsuo, Watanabe Ichiro, Hirayama Atsushi, Nakayama Tomohiro
Department of Medicine, Division of Cardiology, Nihon University School of Medicine, Tokyo, Japan.
Ann Noninvasive Electrocardiol. 2011 Apr;16(2):156-64. doi: 10.1111/j.1542-474X.2011.00423.x.
The International Conference on Harmonization E14 Guideline specifies detailed assessment of QT interval or corrected QT interval prolongation when developing new drugs. We recently devised new software to precisely measure the QT interval.
The QT intervals of all leads for a selected single heart beat were compared between automated measurement with the new software from Fukuda Denshi and manual measurement. With both automated and manual measurement, QT intervals obtained by the tangent method were shorter than those obtained by the differential threshold method, but the extent of correction was smaller. QT interval data obtained by the differential threshold method were more similar to values obtained by visual measurement than were data obtained by the tangent method, but the extent of correction was larger. Variability was related to the T-wave amplitude and to setting the baseline and tangent in the tangent method, while skeletal muscle potential noise affected the differential threshold method. Drift, low-amplitude recordings, and T-wave morphology were problems for both methods. Among the 12 leads, corrections were less frequent for leads II and V(3) -V(6) .
We conclude that, for a thorough assessment of the QT/QTc interval, the tangent method or the differential threshold method appears to be suitable because of smaller interreader differences and better reproducibility. Correction of data should be done by readers who are experienced in measuring the QT interval. It is also important for electrocardiograms to have little noise and for a suitable heart rate and appropriate leads to be selected.
国际协调会议E14指南规定，在研发新药时需对QT间期或校正QT间期延长进行详细评估。我们最近设计了新软件来精确测量QT间期。
比较了使用福田电子的新软件自动测量与手动测量选定单一心搏所有导联的QT间期。自动测量和手动测量时，切线法获得的QT间期均短于微分阈值法，但校正程度较小。与切线法获得的数据相比，微分阈值法获得的QT间期数据与目测值更相似，但校正程度更大。变异性与T波振幅以及切线法中基线和切线的设置有关，而骨骼肌电位噪声影响微分阈值法。两种方法都存在漂移、低振幅记录和T波形态方面的问题。在12个导联中，II导联以及V(3)-V(6)导联的校正较少。
我们得出结论，为全面评估QT/QTc间期，切线法或微分阈值法似乎较为合适，因为其阅片者间差异较小且重现性较好。数据校正应由有测量QT间期经验的阅片者进行。心电图噪声小、选择合适的心率及恰当的导联也很重要。
