QT Dispersion: Does It Change after Percutaneous Coronary Intervention?

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Abstract

Background

Myocardial ischemia is one of several causes of prolonged QT dispersion. The aim of this study was to evaluate the effect that percutaneous coronary intervention has on the depolarization and repolarization parameters of surface electrocardiography in patients with chronic stable angina.

Methods

We assessed the effects of full revascularization in patients with chronic stable angina and single-vessel disease who underwent percutaneous coronary intervention. Twelve-lead electrocardiograms were recorded before intervention and 24 hours subsequently. We measured parameters including QRS duration, QT and corrected QT durations, and JT and corrected JT duration in both electrocardiograms and compared the values.

Results

There were significant differences between the mean QRS interval (0.086 ± 0.01 sec vs. 0.082 ± 0.01 second; p value = 0.01), mean corrected QT dispersion (0.080 ± 0.04 sec vs. 0.068 ± 0.04 sec; p value = 0.001), and mean corrected JT dispersion (0.074 ± 0.04 sec vs. 0.063 ± 0.04 sec; p value = 0.001) before and after percutaneous coronary intervention. No significant differences were found between the other ECG parameters.

Conclusion

Our data indicate that the shortening of corrected QT dispersion and corrected JT dispersion in patients undergoing percutaneous coronary intervention is prominent.

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Most cited references 19

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Measurement, interpretation and clinical potential of QT dispersion.

M. Malik, V. Batchvarov (2000)

QT dispersion was originally proposed to measure spatial dispersion of ventricular recovery times. Later, it was shown that QT dispersion does not directly reflect the dispersion of recovery times and that it results mainly from variations in the T loop morphology and the error of QT measurement. The reliability of both automatic and manual measurement of QT dispersion is low and significantly lower than that of the QT interval. The measurement error is of the order of the differences between different patient groups. The agreement between automatic and manual measurement is poor. There is little to choose between various QT dispersion indices, as well as between different lead systems for their measurement. Reported values of QT dispersion vary widely, e.g., normal values from 10 to 71 ms. Although QT dispersion is increased in cardiac patients compared with healthy subjects and prognostic value of QT dispersion has been reported, values are largely overlapping, both between healthy subjects and cardiac patients and between patients with and without adverse outcome. In reality, QT dispersion is a crude and approximate measure of abnormality of the complete course of repolarization. Probably only grossly abnormal values (e.g. > or =100 ms), outside the range of measurement error may potentially have practical value by pointing to a grossly abnormal repolarization. Efforts should be directed toward established as well as new methods for assessment and quantification of repolarization abnormalities, such as principal component analysis of the T wave, T loop descriptors, and T wave morphology and wavefront direction descriptors.

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Influence of lead selection and population on automated measurement of QT dispersion.

Christopher Macfarlane, H-J Rödger, S McLaughlin (1998)

The study of QT dispersion (QTd) is of increasing clinical interest, but there are very few data in large healthy populations. Furthermore, there is still discussion on the extent to which QTd reflects dispersion of measurement. This study addresses these problems. Twelve-lead ECGs recorded on 1501 apparently healthy adults and 1784 healthy neonates, infants, and children were used to derive normal limits of QTd and QT intervals by use of a fully automated approach. No age gradient or sex differences in QTd were seen and it was found that an upper limit of 50 ms was highly specific. Three-orthogonal-lead ECGs (n=1220) from the Common Standards for Quantitative Electrocardiography database were used to generate derived 12-lead ECGs, which had a significant increase in QTd of 10.1+/-13.1 ms compared with the original orthogonal-lead ECG but a mean difference of only 1.63+/-12.2 ms compared with the original 12-lead ECGs. In a population of 361 patients with old myocardial infarction, there was a statistically significant increase in mean QTd compared with that of the adult normal group (32.7+/-10.0 versus 24.53+/-8.2 ms; P<0. 0001). An estimate of computer measurement error was also obtained by creating 2 sets of 1220 ECGs from the original set of 1220. The mean error (difference in QTd on a paired basis) was found to be 0. 28+/-9.7 ms. These data indicate that QTd is age and sex independent, has a highly specific upper normal limit of 50 ms, is significantly lower in the 3-orthogonal-lead than in the 12-lead ECG, and is longer in patients with a previous myocardial infarction than in normal subjects.

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QT dispersion is determined by the extent of viable myocardium in patients with chronic Q-wave myocardial infarction.

Daniel E. Voth, Kathryn Wagner, U. Sechtem … (1997)

QT dispersion is lower in patients with successful thrombolysis after acute myocardial infarction, suggesting that QT dispersion may be determined by the extent of viable and scarred myocardium. To test this hypothesis, QT dispersion was measured in a 12-lead resting ECG in 44 patients with chronic Q-wave myocardial infarction. To assess the extent of viable and scarred myocardium, all patients underwent F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET). In addition, all patients had revascularization of the infarct-related artery and repeated angiography 4 months later. QT dispersion was lower (53+/-20 versus 94+/-24 ms, P or = 50% of normalized, maximum FDG uptake) than in patients with only minimal residual viability. Average FDG uptake of the infarct region and FDG defect size were significantly related to QT dispersion (r=.64, P<.0001; r=.67, P<.0001), whereas ejection fraction was not (r<.1, P=NS). QT dispersion of < or = 70 ms had a sensitivity of 85% and a specificity of 82% to predict viable myocardium in the infarct region. QT dispersion was also lower in patients with improvement of left ventricular function 4 months after revascularization (54+/-21 versus 88+/-30 ms, P=.0003). QT dispersion of < or = 70 ms had a sensitivity of 83% and a specificity of 71% to predict improvement of left ventricular function. QT dispersion is determined by the amount of viable myocardium in the infarct region and may serve as a novel, rapidly available marker of substantial viability in the infarct region of patients with chronic Q-wave myocardial infarction.

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Author and article information

Journal

Journal ID (nlm-ta): J Tehran Heart Cent

Journal ID (iso-abbrev): J Tehran Heart Cent

Journal ID (publisher-id): JTHC

Title: The Journal of Tehran Heart Center

Publisher: Tehran University of Medical Sciences

ISSN (Print): 1735-5370

ISSN (Electronic): 2008-2371

Publication date (Print): Winter 2011

Publication date Collection: 2011

Publication date (Electronic): 28 February 2011

Volume: 6

Issue: 1

Pages: 19-23

Affiliations

[1 ]Imam Khomeini Hospital, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.

[2 ]Golestan Hospital, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.

Author notes

[* ] Corresponding Author: Mohammad Alasti, Assistant Professor of Cardiology, Jondishpour University of Medical Sciences, Imam Khomeini Hospital, Azadegan, Avenue, Ahwaz, Iran. Tel: +98 611 4457205. Fax: +98 611 4457205. E-mail: alastip@ 123456gmail.com .

Article

Publisher ID: jthc-6-19

PMC ID: 3466863

PubMed ID: 23074600

SO-VID: e39129fd-20e8-44a0-a582-1aae28c28f1c

License:

This is an open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0), which allows users to read, copy, distribute and make derivative works for non-commercial purposes from the material, as long as the author of the original work is cited properly.

QT Dispersion: Does It Change after Percutaneous Coronary Intervention?

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Abstract

Background

Methods

Results

Conclusion

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Cardiovascular Innovations and Applications

Most cited references 19

Measurement, interpretation and clinical potential of QT dispersion.

Influence of lead selection and population on automated measurement of QT dispersion.

QT dispersion is determined by the extent of viable myocardium in patients with chronic Q-wave myocardial infarction.

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