Abstract：Objective To develop a new method for evaluating QT interval prolongation and to demonstrate its validity. Methods A total of 1 634 healthy people were enrolled as research objects and their ECG data were divided into groups according to heart rate. The 97.5% quantile of QT interval at different heart rate was calculated; polynomial fitting of these QT quantiles and heart rate was performed; and then we obtained the risk line of nomogram for evaluating QT interval prolongation. The new QT nomogram, Chan's nomogram and Bazett's formula(QTc=440 ms) were separately utilized in diagnosing congenital long QT syndrome(LQTS) and druginduced torsade de pointes(TdP). The diagnostic efficiency was compared among the three methods. ResultsIn the diagnosis of congenital LQTS, the sensitivity and specificity of the new QT nomogram was 95.7% and 97.5%, respectively; Chan's nomogram showed a sensitivity of 74.1% and a specificity of 99.2%; the sensitivity and specificity of Bazett's formula was separately 98.6% and 90.5%. In the diagnosis of druginduced TdP, the sensitivity and specificity of the new QT nomogram was 95.8% and 97.1%, respectively; Chan's nomogram showed a sensitivity of 90.2% and a specificity of 99.3%; the sensitivity and specificity of Bazett's formula was separately 97.2% and 86.8%. Conclusion The new QT nomogram we developed is a simpletouse tool for clinical risk evaluation. It can predict risks for congenital LQTS and druginduced TdP more precisely if compared with other methods.
刘国才, 李洁, 巨立中, 马玉贤, 姬秋和. QT间期延长评估的新方法[J]. 实用心电学杂志, 2017, 26(6): 437-442.
LIU Guo-Cai, LI Jie, JU Li-Zhong, MA Yu-Xian, JI Qiu-He. An improved method for evaluating QT interval prolongation. JOURNAL OF PRACTICAL ELECTROCARDIOLOGY, 2017, 26(6): 437-442.
2017, Vol. 26 
