Luo Shen, Michler Kurt, Johnston Paul, Macfarlane Peter W
Burdick/Quinton Cardiology Systems Inc., Deerfield, WI 53531, USA.
J Electrocardiol. 2004;37 Suppl:81-90. doi: 10.1016/j.jelectrocard.2004.08.030.
The corrected QT interval (QTc) is widely used in pharmaceutical studies and clinical practice. Bazett's QT correction formula is still the most popular, despite Simonson's warning in 1961 that it could not be recommended. Other QTc formulae, e.g. Fridericia, Framingham, and Hodges, are also used. This study compares these four formulae using 10,303 normal ECGs recorded from four US hospitals. QT intervals were measured by the same computer program on ECGs confirmed by physicians. The distributions of QTc based on Fridericia, Framingham, and Hodges formulae were similar but Bazett's was significantly wider. The global group QTc-heart rate (HR) correlation coefficients were calculated as Bazett 0.33, Fridericia 0.24, Framingham 0.26, and Hodges 0.11, with the uncorrected QT-HR correlation being 0.82. Overall by far, Hodges QTc is significantly less correlated with HR compared to the others. Certain subgroup correlations of gender and low, mid, or high HR show that one individual formula can out-perform the others, whereby automated selection of QT correction formula based on the patient's HR and gender could be implemented as another option in products. The upper normal limits of corrected QTc were determined by excluding the top 2% from the global distribution charts as follows: Bazett 483 ms, Fridericia 460 ms, Framingham 457 ms, and Hodges 457 ms. Whether for males and/or females, the middle range of HR from 60 to 99 bpm has similar upper normal limits of QTc for all formulae except Bazett. Numerous references recommend 420 to 440 ms as the threshold for reporting prolonged QTc when using Bazett's formula. Based on this database, 30% of apparently normal ECGs would be reported as having abnormal QT intervals for the 440 ms threshold, or 10% if 460 ms is chosen, compared to <2% for the other formulae. It was also noted that QT has a linear trend with HR but not with RR.
校正QT间期（QTc）在药物研究和临床实践中被广泛应用。尽管西蒙森在1961年就警告过巴泽特的QT校正公式不可推荐，但它仍是最常用的公式。其他QTc公式，如弗里德里西亚公式、弗雷明汉公式和霍奇斯公式也被使用。本研究使用从美国四家医院记录的10303份正常心电图对这四种公式进行了比较。QT间期由同一计算机程序在经医生确认的心电图上进行测量。基于弗里德里西亚公式、弗雷明汉公式和霍奇斯公式的QTc分布相似，但巴泽特公式的分布明显更宽。全局组QTc与心率（HR）的相关系数计算如下：巴泽特公式为0.33，弗里德里西亚公式为0.24，弗雷明汉公式为0.26，霍奇斯公式为0.11，未校正的QT与HR的相关系数为0.82。总体而言，到目前为止，与其他公式相比，霍奇斯QTc与HR的相关性明显更低。某些性别以及低、中、高心率亚组的相关性表明，某个公式可能比其他公式表现更优，因此基于患者的HR和性别自动选择QT校正公式可作为产品中的另一种选择。校正QTc的正常上限是通过从全局分布图中排除前2%的数据来确定的，具体如下：巴泽特公式为483毫秒，弗里德里西亚公式为460毫秒，弗雷明汉公式为457毫秒，霍奇斯公式为457毫秒。无论对于男性和/或女性，除巴泽特公式外，心率在60至99次/分钟的中间范围对于所有公式的QTc正常上限相似。许多参考文献推荐在使用巴泽特公式时，将420至440毫秒作为报告QTc延长的阈值。基于该数据库，对于440毫秒的阈值，30%的看似正常的心电图会被报告为QT间期异常；如果选择460毫秒，则为10%，而其他公式的这一比例小于2%。还注意到QT与HR呈线性趋势，但与RR无此趋势。
