Session S93.1

Impact of Different Autonomic Balances on Early and Late Cardiac Repolarization Duration

R Handzel*, JP Couderc

University of Rochester
Rochester, NY, USA

Background: Repolarization heterogeneity has been recognized as an important factor in arrhythmogenesis. However, there is a lack of markers to quantify an increase in repolarization heterogeneity from the surface ECG. Inter-lead QT dispersion was used for years but it has been progressively abandoned because it is impacted by measurement artifacts. We have developed novel methods to quantify repolarization heterogeneity based on the morphology of the T-loop. However, these new technologies have not been well characterized yet. The objective of this study is to assess the impact of changes in autonomic balance (ANS) on these novel repolarization parameters.
Methods: The early and late repolarization duration (ERD and LRD) are interval measurements dependent on the morphology of the T-loop. They are computed from the representation on this loop in its preferential plane. All measurements were done using the COMPAS software that was developed at the University of Rochester, Rochester, NY, USA. We compared the values of ERD and LRD in healthy individuals under different ANS regulation: from supine to standing position and then to sitting. We evaluated the changes in ERD and LRD values according to the body position and the associated autonomic balance. A cohort of 63 patients had a 3-lead-ECG (200Hz, 16 bit resolution) recorded continuously across such protocol. Healthy individuals were switched from supine to standing to sitting in two minute intervals. Each ECG was analyzed 20 seconds prior to the switch in position.
Results: The difference in values (ms) for supine-standing were: RR:124*±114, QT:16.9*±14.8, QTcF:-1.98±11.2, QTcB:-46.6*±47.7, TpTe:-0.657±10.1, ERD50%:-1.76±10.6, LRD50%:-0.943±7.47 and the difference in values for supine-sitting were: RR:36.2*±72.1, QT:11.9*±11.2, QTcF:6.78*±8.66, QTcB:-4.28±28.0, TpTe: 0.801±3.89, ERD50%:0.656±7.55 LRD50%:0.369±8.21. No significant differences were found between positions for ERD50% and LRD50% while QT and QTc revealed statistical differences under different autonomic regulation.
Conclusion: The results suggest that the effect of the autonomic regulation of the heart and its effect on the ventricular repolarization as a minimal impact on the ERD and LRD parameters while QT-based measurement revealed some statistically significant changes.

(Abstract Control Number: 3)