QT间期延长评估的新方法

An improved method for evaluating QT interval prolongation

目的提出一个评估QT间期延长的新方法,并验证其有效性。方法纳入1 634名健康受试者,根据心率对其心电图数据进行分组。计算不同心率所对应QT间期的97.5%分位数,并将这些QT分位数针对心率进行多项式拟合,得到用以评估QT间期延长的诺模图风险线。再利用新QT诺模图、Chan诺模图以及Bazett公式(QTc=440 ms),分别诊断先天性长QT间期综合征(long QT syndrome,LQTS)和药物诱导的尖端扭转型室速(torsade de pointes,TdP),以比较它们的诊断效能。结果用新QT诺模图诊断先天性LQTS的灵敏度和特异度分别为95.7%和97.5%,用Chan诺模图诊断时分别为74.1%和99.2%,而用Bazett公式诊断时分别为98.6%和90.5%。用新QT诺模图诊断药物诱导的TdP的灵敏度和特异度分别为95.8%和97.1%,用Chan诺模图诊断时分别为90.2%和99.3%,而用Bazett公式诊断时分别为97.2%和86.8%。结论新QT诺模图是一个简单易用的临床风险评估工具,相对其他方法而言能更准确地预测先天性LQTS和药物诱导的TdP的风险。

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 drug-induced torsade de pointes( TdP). The diagnostic efficiency was compared among the three methods. Results In the diagnosis of congenital LQTS,the sensitivity and specificity of the new QT nomogram was 95. 7% and97. 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 diagno-sis of drug-induced TdP,the sensitivity and specificity of the new QT nomogram was 95. 8% and97. 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 simple-to-use tool for clinical risk evaluation. It can predict risks for congenital LQTS and drug-induced TdP more precisely if compared with other methods.