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QT dispersion: Clinical applications

Velislav Batchvarov, MD
A John Camm, MD
Section Editor
Bernard J Gersh, MB, ChB, DPhil, FRCP, MACC
Deputy Editor
Brian C Downey, MD, FACC


The QT interval duration varies between leads on the standard electrocardiogram (ECG), Frank orthogonal leads, and body surface potential maps [1-6]. These interlead differences, called QT dispersion or QT range, were proposed as an index of the spatial dispersion of the ventricular recovery times [7]. This measurement was an attempt to distinguish between myocardium that is homogeneous from myocardium that displays inhomogeneity, which is accompanied by increased dispersion of the ventricular recovery times and prolongation of repolarization. In reality, QT dispersion is a crude and approximate measure of a general abnormality of repolarization [8].

QT dispersion was developed in an effort to improve on ECG measures used in clinical practice, including the QT interval and its heart rate-corrected value (QTc) and the description of the ST-T morphology, often using vague terms such as "non-specific ST-T wave changes." However, there has been much concern about the validity of the concept and the methodology of the measurement. Despite ongoing controversy, there are a number of reasonable conclusions about the reliability and applicability of the technique [8,9].

The clinical application of QT dispersion will be reviewed here. The pathophysiology and measurement of QT dispersion are discussed elsewhere. (See "QT dispersion: Measurement and interpretation".)


Reported values of QT dispersion vary widely, ranging from 10 to 71 msec in normal subjects [8,10-13]. In a review of 8455 healthy control subjects of various ages, including healthy children, the mean QT dispersion values ranged from 10 to 71 msec (mean 33 msec; median 37 msec) (figure 1) [8]. There is little or no sex difference in QT dispersion [14-16]. Age-related differences, if present, appear to be small (<10 msec) [13,17].

Similar values have been noted in large studies and literature reviews that suggested that the upper normal limit of QT dispersion in normal and healthy subjects is 65 msec [10,18]. In contrast, other reports claim that QT dispersion >40 ms has a sensitivity and specificity of 88 and 57 percent, respectively, for predicting the inducibility of sustained ventricular tachycardia during an electrophysiology study [19]. However, in most of the studies with positive results, values for QT dispersion are well within the demonstrated measurement error of both manual and automatic methods. Another problem is that some prospective studies only provided data for the heart rate-corrected QT (QTc) dispersion [20,21].

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Literature review current through: Nov 2017. | This topic last updated: Sep 15, 2016.
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