Heterogeneity in depolarization and repolarization among regions of cardiac cells has long been recognized as a major factor in cardiac arrhythmogenesis. This fundamental principle has motivated development of noninvasive techniques for quantification of heterogeneity using the surface electrocardiogram (ECG). The initial approaches focused on interval analysis such as interlead QT dispersion and T_peak–T_end difference. However, because of inherent difficulties in measuring the termination point of the T wave and commonly encountered irregularities in the apex of the T wave, additional techniques have been pursued. The newer methods incorporate assessment of the entire morphology of the T wave and in some cases of the R wave as well. This goal has been accomplished using a number of promising vectorial approaches with the resting 12-lead ECG. An important limitation of vectorcardiographic analyses is that they require exquisite stability of the recordings and are not inherently suitable for use in exercise tolerance testing (ETT) and/or ambulatory ECG monitoring for provocative stress testing or evaluation of the influence of daily activities on cardiac electrical instability. The objectives of the present review are to describe a technique that has been under clinical evaluation for nearly a decade, termed “interlead ECG heterogeneity.” Preclinical testing data will be briefly reviewed. We will discuss the main clinical findings with regard to sudden cardiac death risk stratification, heart failure evaluation, and myocardial ischemia detection using standard recording platforms including resting 12-lead ECG, ambulatory ECG monitoring, ETT, and pharmacologic stress testing in conjunction with single-photon emission computed tomography myocardial perfusion imaging.

中文翻译：

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Interlead ECG异质性评估的临床应用谱：从心肌缺血检测到心脏猝死风险分层

心脏细胞区域之间去极化和复极化的异质性长期以来被认为是心律失常的主要因素。这一基本原则推动了使用表面心电图 (ECG) 量化异质性的非侵入性技术的发展。最初的方法侧重于间隔分析，例如间隔 QT 离散度和 T_峰-T_结束不同之处。然而，由于测量 T 波终止点的固有困难以及 T 波顶点中常见的不规则性，已寻求其他技术。较新的方法包括对 T 波的整个形态的评估，在某些情况下也包括对 R 波的评估。这一目标已通过使用多种有前途的矢量方法与静止 12 导联心电图实现。矢量心电图分析的一个重要限制是它们需要非常稳定的记录，并且本质上不适合用于运动耐量测试 (ETT) 和/或动态心电图监测以进行刺激性压力测试或评估日常活动对心脏电的影响不稳定。本综述的目的是描述一种已进行近十年临床评估的技术，称为“interlead ECG 异质性”。将简要回顾临床前测试数据。我们将讨论使用标准记录平台（包括静息 12 导联心电图、动态心电图监测、ETT 和药物负荷测试以及单-光子发射计算机断层扫描心肌灌注显像。