Local atrial bipolar electrogram voltage drops during cardiac magnetic resonance guided catheter ablation of typical atrial flutter: Associations with delivered radiofrequency energy and peri-procedural imaging

Hedwig M J M Nies; Dominik Linz; Geertruida P Bijvoet; Robert J Holtackers; Justin G L M Luermans; Kim E H M van der Velden; Joachim E Wildberger; Kevin Vernooy; Sander M J van Kuijk; Casper Mihl; Sevasti-Maria Chaldoupi

doi:10.1016/j.hroo.2024.08.015

Local atrial bipolar electrogram voltage drops during cardiac magnetic resonance guided catheter ablation of typical atrial flutter: Associations with delivered radiofrequency energy and peri-procedural imaging

Heart Rhythm O2. 2024 Sep 6;5(11):778-787. doi: 10.1016/j.hroo.2024.08.015. eCollection 2024 Nov.

Authors

Hedwig M J M Nies^{1

2}, Dominik Linz^{1

3

4}, Geertruida P Bijvoet^{1

3}, Robert J Holtackers^{1

2}, Justin G L M Luermans^{1

3}, Kim E H M van der Velden⁵, Joachim E Wildberger^{1

2}, Kevin Vernooy^{1

3}, Sander M J van Kuijk⁶, Casper Mihl^{1

2}, Sevasti-Maria Chaldoupi³

Affiliations

¹ Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands.
² Department of Radiology & Nuclear Medicine, Maastricht University Medical Centre, Maastricht, The Netherlands.
³ Department of Cardiology, Maastricht University Medical Centre, Maastricht, The Netherlands.
⁴ Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
⁵ Department of Anesthesiology, Maastricht University Medical Centre, Maastricht, The Netherlands.
⁶ Department of Clinical Epidemiology and Medical Technology Assessment, Maastricht University Medical Center, Maastricht, The Netherlands.

Abstract

Background: Cardiac magnetic resonance (CMR)-guided catheter ablation of the cavotricuspid isthmus (CTI) has been proven feasible, but determinants of local electrogram (EGM) voltage drops during radiofrequency (RF) applications are unknown.

Objective: The purpose of this study was to investigate local atrial bipolar EGM voltage drops and the association with delivered RF energy and anatomical information derived from peri-procedural CMR imaging.

Methods: In consecutive patients undergoing CMR-guided CTI ablation procedures, relative EGM voltage drops for RF applications ≥20 seconds were calculated. Pre- and post-ablation CMR imaging was performed. Associations of relative EGM voltage drops with patient characteristics, delivered RF energy, and CTI anatomy were analyzed.

Results: In total, 216 RF applications were evaluated from 12 patients (18 ± 5 applications/patient). EGM voltage amplitude at baseline was significantly higher in the group with the strongest relative EGM voltage drop (P < .05), whereas RF ablation settings (duration, power, temperature) and lesion characteristics (impedance drop, slope of impedance drop) did not differ. The EGM voltage amplitude at baseline (P < .001), left ventricular ejection fraction (LVEF) (P = .020), right atrium volume index (RAVI) (P = .027), and CTI line length (P = .026) showed the strongest association with relative EGM voltage drop. Four of 12 patients (33%) underwent a re-do procedure, 2 patients showed a regional late reconnection, which could be visually identified in the T₂-weighted images (T2WI) of the index procedure.

Conclusion: Local EGM voltage amplitude, LVEF, RAVI, and CTI length are associated with relative EGM voltage drop during CMR-guided CTI ablation. Post-ablation CMR imaging during the index procedure may help to identify areas of late reconnection.

Keywords: Ablation lesion assessment; Atrial flutter; Durable ablation lesion formation; Interventional cardiac MRI (iCMR); Late electrical reconnection; Local atrial bipolar electrogram; Radiofrequency catheter ablation.