Variant electrical activation and recovery in normal human hearts revealed by noninvasive electrocardiographic imaging

Abstract

AbstractBackground and aimsAlthough electrical activity of the normal human heart is well-characterized by the 12-lead electrocardiogram, detailed insights into within-subject and between-subject variations of ventricular activation and recovery by noninvasive electroanatomic mapping are lacking. We characterized human epicardial activation and recovery within and between normal subjects using noninvasive electrocardiographic imaging (ECGI) as a basis to better understand pathology.MethodsEpicardial activation and recovery were assessed by ECGI in 22 normal subjects, 4 subjects with bundle branch block (BBB) and 4 with long-QT syndrome (LQTS). We compared characteristics between the ventricles (LV versus RV), sexes and age groups (<50y/≥50y (years)). Pearson’s correlation coefficient (CC) was used for within-subject and between- subject comparisons.ResultsAge of normal subjects averaged 49±14 years, 6/22 were male, and no structural/electrical heart disease was present. Average activation time was longer in LV than in RV, but not different by sex or age. Electrical recovery was similar for the ventricles, but started earlier and was on average shorter in males than females. Median CCs of between-subject comparisons of the ECG signals, activation and recovery patterns were 0.61, 0.32 and 0.19, respectively. Within-subject beat-to-beat comparisons yielded higher CCs (0.98, 0.89 and 0.82, respectively). Activation and/or recovery patterns of patients with BBB or LQTS contrasted significantly with those found in the normal population.ConclusionActivation and recovery patterns vary profoundly between normal subjects, but are stable individually beat to beat, with a male preponderance to shorter recovery. Individual characterization by ECGI at baseline serves as reference to better understand the emergence, progression and treatment of electrical heart disease.Graphical abstractCentral illustration.Application of electrocardiographic imaging (ECGI) in healthy controls allows to study normal epicardial activation and recovery patterns. Top: Although all subjects had a normal ECG, we found that their underlying activation time (AT) and recovery time (RT) patterns could be profoundly different. Still, beat-to-beat AT and RT patterns within one subject were relatively similar. Bottom: On a population level, we found that average right-ventricular (RV) AT was lower than left-ventricular (LV) AT, and both first and average RT were lower in males than in females.