Dan Roden
Faculty Member
Last active: 3/24/2020

Electrophysiologic substrate in congenital Long QT syndrome: noninvasive mapping with electrocardiographic imaging (ECGI).

Vijayakumar R, Silva JNA, Desouza KA, Abraham RL, Strom M, Sacher F, Van Hare GF, Haïssaguerre M, Roden DM, Rudy Y
Circulation. 2014 130 (22): 1936-1943

PMID: 25294783 · PMCID: PMC4245321 · DOI:10.1161/CIRCULATIONAHA.114.011359

BACKGROUND - Congenital Long QT syndrome (LQTS) is an arrhythmogenic disorder that causes syncope and sudden death. Although its genetic basis has become well-understood, the mechanisms whereby mutations translate to arrhythmia susceptibility in the in situ human heart have not been fully defined. We used noninvasive ECG imaging to map the cardiac electrophysiological substrate and examine whether LQTS patients display regional heterogeneities in repolarization, a substrate that promotes arrhythmogenesis.

METHODS AND RESULTS - Twenty-five subjects (9 LQT1, 9 LQT2, 5 LQT3, and 2 LQT5) with genotype and phenotype positive LQTS underwent ECG imaging. Seven normal subjects provided control. Epicardial maps of activation, recovery times, activation-recovery intervals, and repolarization dispersion were constructed. Activation was normal in all patients. However, recovery times and activation-recovery intervals were prolonged relative to control, indicating delayed repolarization and abnormally long action potential duration (312±30 ms versus 235±21 ms in control). Activation-recovery interval prolongation was spatially heterogeneous, with repolarization gradients much steeper than control (119±19 ms/cm versus 2.0±2.0 ms/cm). There was variability in steepness and distribution of repolarization gradients between and within LQTS types. Repolarization gradients were steeper in symptomatic patients (130±27 ms/cm in 12 symptomatic patients versus 98±19 ms/cm in 13 asymptomatic patients; P<0.05).

CONCLUSIONS - LQTS patients display regions with steep repolarization dispersion caused by localized action potential duration prolongation. This defines a substrate for reentrant arrhythmias, not detectable by surface ECG. Steeper dispersion in symptomatic patients suggests a possible role for ECG imaging in risk stratification.

© 2014 American Heart Association, Inc.

MeSH Terms (12)

Adolescent Adult Child Cohort Studies Electrocardiography Epicardial Mapping Female Humans Long QT Syndrome Male Middle Aged Young Adult

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