Repolarization abnormalities unmasked with exercise in sudden cardiac death survivors with structurally normal hearts

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Title: Repolarization abnormalities unmasked with exercise in sudden cardiac death survivors with structurally normal hearts
Authors: Leong, KM
Ng, FS
Roney, C
Cantwell, C
Shun-Shin, MJ
Linton, NW
Whinnett, ZI
Lefroy, DC
Davies, DW
Harding, SE
Lim, PB
Francis, D
Peters, NS
Varnava, AM
Kanagaratnam, P
Item Type: Journal Article
Abstract: BACKGROUND: Models of cardiac arrhythmogenesis predict that non-uniformity in repolarization and/or depolarization promotes ventricular fibrillation and is modulated by autonomic tone, but this is difficult to evaluate in patients. We hypothesize that such spatial heterogeneities would be detected by non-invasive ECG imaging (ECGi) in sudden cardiac death (SCD) survivors with structurally normal hearts under physiological stress. METHODS: ECGi was applied to 11 SCD survivors, 10 low-risk Brugada Syndrome patients (BrS) and 10 controls undergoing exercise treadmill testing. ECGi provides whole heart activation maps and > 1200 unipolar electrograms over the ventricular surface from which global dispersion of activation recovery interval (ARI) and regional delay in conduction were determined. These were used as surrogates for spatial heterogeneities in repolarization and depolarization. Surface ECG markers of dispersion (QT and Tpeak-end intervals) were also calculated for all patients for comparison. RESULTS: Following exertion, the SCD group demonstrated the largest increase in ARI dispersion compared to BrS and control groups (13±8 ms vs 4±7 ms vs 4±5 ms; p = 0.009), with baseline dispersion being similar in all groups. In comparison, surface ECG markers of dispersion of repolarisation were unable to discriminate between the groups at baseline or following exertion. Spatial heterogeneities in conduction were also present following exercise but were not significantly different between SCD survivors and the other groups. CONCLUSION: Increased dispersion of repolarization is apparent during physiological stress in SCD survivors and is detectable with ECGi but not with standard ECG parameters. The electrophysiological substrate revealed by ECGi could be the basis of alternative risk-stratification techniques. This article is protected by copyright. All rights reserved.
Issue Date: 1-Nov-2017
Date of Acceptance: 25-Sep-2017
ISSN: 1045-3873
Publisher: Wiley
Start Page: 115
End Page: 126
Journal / Book Title: Journal of Cardiovascular Electrophysiology
Volume: 29
Issue: 1
Copyright Statement: This is the peer reviewed version of the following article: Leong KMW, Ng FS, Roney C, et al. Repolarization abnormalities unmasked with exercise in sudden cardiac death survivors with structurally normal hearts. J Cardiovasc Electrophysiol. 2018;29:115–126, which has been published in final form at  This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.
Sponsor/Funder: British Heart Foundation
British Heart Foundation
British Heart Foundation
Rosetrees Trust
Funder's Grant Number: FS/13/44/30291
Keywords: ECGi
noninvasive electrocardiographic imaging
sudden cardiac death
Non-invasive electrocardiographic imaging
1102 Cardiovascular Medicine And Haematology
Cardiovascular System & Hematology
Publication Status: Published
Appears in Collections:Faculty of Engineering
National Heart and Lung Institute
Faculty of Medicine

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