Pulmonary Veins Function as Echo Chambers in Persistent Atrial Fibrillation: Circuitous Re-Entry Generates Outgoing Wavefronts

Shu Meng; Ahmed M Al-Kaisey; Ramanathan Parameswaran; Nicholas Sunderland; David M Budgett; Peter M Kistler; Bruce H Smaill; Jonathan M Kalman

doi:10.1016/j.jacep.2024.03.025

Pulmonary Veins Function as Echo Chambers in Persistent Atrial Fibrillation: Circuitous Re-Entry Generates Outgoing Wavefronts

JACC Clin Electrophysiol. 2024 May 1:S2405-500X(24)00260-3. doi: 10.1016/j.jacep.2024.03.025. Online ahead of print.

Authors

Shu Meng¹, Ahmed M Al-Kaisey², Ramanathan Parameswaran², Nicholas Sunderland³, David M Budgett¹, Peter M Kistler⁴, Bruce H Smaill¹, Jonathan M Kalman⁵

Affiliations

¹ Auckland Bioengineering Institute, University of Auckland, Auckland New Zealand.
² Department of Medicine, University of Melbourne, Melbourne, Australia; Department of Cardiology, Royal Melbourne Hospital, Melbourne, Australia.
³ Bristol Heart Institute, Bristol University, Bristol, United Kingdom.
⁴ Department of Medicine, University of Melbourne, Melbourne, Australia; Heart Centre, Alfred Hospital, Melbourne, Australia; Baker IDI Heart & Diabetes Institute, Melbourne, Australia.
⁵ Department of Medicine, University of Melbourne, Melbourne, Australia; Department of Cardiology, Royal Melbourne Hospital, Melbourne, Australia; Baker IDI Heart & Diabetes Institute, Melbourne, Australia. Electronic address: jon.kalman@mh.org.au.

PMID: 38752958
DOI: 10.1016/j.jacep.2024.03.025

Abstract

Background: Although the substrate in persistent atrial fibrillation (PeAF) is not limited to the pulmonary veins (PVs), PV isolation (PVI) remains the cornerstone ablation strategy.

Objectives: The aim of this study was to describe the mechanism of outgoing wavefronts (WFs) originating in the PV sleeves during PeAF.

Methods: Eleven patients presenting for first-time PeAF ablation were recruited (mean age 63.1 ± 10.9 years, 91% men). A 64-electrode catheter (Constellation; 38 mm) was positioned within the PV under fluoroscopic guidance. An inverse mapping technique was used to reconstruct unipolar atrial electrograms on the PV surface, and the resulting phase maps were used to identify incoming and outgoing WFs at the PV junction and to classify focal and re-entrant activity within the PV sleeves.

Results: During PeAF, the PVs gave rise to outgoing WFs with a frequency of 3.7 s^-1 (Q1-Q3: 3.4-5.4 s^-1) compared with 3.6 s^-1 (Q1-Q3: 2.8-4.2 s^-1) for incoming WFs. Circuitous macroscopic re-entry was the dominant mechanism driving outgoing WFs (frequency of re-entry 2.7 s^-1 [Q1-Q3: 2.0-3.3 s^-1] compared with focal activity 1.4 s^-1 [Q1-Q3: 1.1-1.5 s^-1]; P < 0.006). This was initiated by incoming WFs in 80% of cases. Consecutive focal activation from the same location was infrequent (10.0% ± 6.6%, n = 10). Rotors ≥360° were never observed. The median ratio (R) of outgoing to incoming WF frequency was 1.14 (Q1-Q3: 0.84-1.75), with R > 1 in 6 of 11 PVs.

Conclusions: Electric activity generated by PV sleeves during PeAF is due mainly to circuitous re-entry initiated by incoming waves, frequently with R > 1. That is, the PVs act less as drivers of atrial fibrillation than as "echo chambers" that sustain and amplify fibrillatory activity.

Keywords: 3-dimensional; atrial fibrillation; fibrillatory drivers; intracardiac electric mapping; phase mapping.