Understanding repolarization in the intracardiac unipolar electrogram: A long-lasting controversy revisited

Job Stoks; Laura R Bear; Johan Vijgen; Paul Dendale; Ralf Peeters; Paul G A Volders; Matthijs J M Cluitmans

doi:10.3389/fphys.2023.1158003

Understanding repolarization in the intracardiac unipolar electrogram: A long-lasting controversy revisited

Front Physiol. 2023 Apr 7:14:1158003. doi: 10.3389/fphys.2023.1158003. eCollection 2023.

Authors

Job Stoks^{1

2

3}, Laura R Bear⁴, Johan Vijgen³, Paul Dendale³, Ralf Peeters², Paul G A Volders¹, Matthijs J M Cluitmans¹

Affiliations

¹ Department of Cardiology, CARIM, Maastricht University Medical Center+, Maastricht, Netherlands.
² Department of Advanced Computing Sciences, Maastricht University, Maastricht, Netherlands.
³ Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium.
⁴ IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Bordeaux, France.

Abstract

Background: The optimal way to determine repolarization time (RT) from the intracardiac unipolar electrogram (UEG) has been a topic of debate for decades. RT is typically determined by either the Wyatt method or the "alternative method," which both consider UEG T-wave slope, but differently. Objective: To determine the optimal method to measure RT on the UEG. Methods: Seven pig hearts surrounded by an epicardial sock with 100 electrodes were Langendorff-perfused with selective cannulation of the left anterior descending (LAD) coronary artery and submersed in a torso-shaped tank containing 256 electrodes on the torso surface. Repolarization was prolonged in the non-LAD-regions by infusing dofetilide and shortened in the LAD-region using pinacidil. RT was determined by the Wyatt (t_Wyatt) and alternative (t_Alt) methods, in both invasive (recorded with epicardial electrodes) and in non-invasive UEGs (reconstructed with electrocardiographic imaging). t_Wyatt and t_Alt were compared to local effective refractory period (ERP). Results: With contact mapping, mean absolute error (MAE) of t_Wyatt and t_Alt vs. ERP were 21 ms and 71 ms, respectively. Positive T-waves typically had an earlier ERP than negative T-waves, in line with theory. t_Wyatt -but not t_Alt-shortened by local infusion of pinacidil. Similar results were found for the non-invasive UEGs (MAE of t_Wyatt and t_Alt vs. ERP were 30 ms and 92 ms, respectively). Conclusion: The Wyatt method is the most accurate to determine RT from (non) invasive UEGs, based on novel and historical analyses. Using it to determine RT could unify and facilitate repolarization assessment and amplify its role in cardiac electrophysiology.

Keywords: ECGI; T wave; alternative method; electrogram; electrophysiology; repolarization; wyatt.

Grants and funding

This study was supported by the Special Research Fund (BOF) of Hasselt University (BOF17DOCMA15) and the Maastricht University Medical Center (MUMC+) to JS, the Hein Wellens Foundation, Health Foundation Limburg (Maastricht, Netherlands), and a Veni grant from the Netherlands Organization for Scientific Research (TTW16772) to MC; and the Netherlands CardioVascular Research Initiative (CVON 2017-13 VIGILANCE and CVON 2018B030 PREDICT2), Den Haag, Netherlands to PV. This work was furthermore supported by the French National Research Agency (ANR-10-IAHU04-LIRYC) and the Leducq foundation transatlantic network of excellence RHYTHM network (16CVD02).