Condensed abstract
Atrial fibrillation propagation patterns including localised irregular
activation patterns (LIA), rotational activation patterns (LRA) and
focal firing (FF) can be identified using non-contact mapping. LIA is
characterised by repeated localised wavefront directional change and
demonstrates high spatiotemporal stability alongside regions with high
frequency FF. In contrast, LRA is transient and inconsistent. We
therefore speculate that regions of high frequency LIA may best reflect
atrial structural aberrations whilst LRA is a functional reflection of
wavefront dynamics.
Introduction
The limited efficacy of pulmonary vein isolation for the ablation of
persistent atrial fibrillation (persAF) has resulted in concerted
efforts to identify non-pulmonary vein mechanisms responsible for AF
maintenance. This has led to the development of techniques to facilitate
mapping of the underlying atrial electrophysiology with the aim of
revealing fibrillatory mechanisms and guiding targeted ablation.(1-6)
Non-contact charge-density mapping allows visualisation of whole chamber
activation. Wavefront patterns are scrutinised in real time at every
vertex of the chamber surface (approximately 3,500) by in an inbuilt
application (AcQTrack, Acutus Medical). Non-planar, complex localised
patterns of propagation are identified and characterised as localised
rotational activation (LRA), localised irregular activation (LIA) and
focal firing (FF)(see figure 1).(7) To be classed as LRA, a smooth
depolarisation wavefront has to rotate 360 degrees around a central
point. LIA is characterised by a difference in angle between conduction
that enters and leaves a confined region exceeding a threshold of 90
degrees (and not meeting the criteria for LRA above). In contrast, FF is
defined as activation of a primary vertex that precedes adjoining
neighbours and extends centrifugally from this primary vertex.
A catheter ablation approach aimed at targeting these zones has been
evaluated in one prospective observational study,(6) but little work has
been done exploring the spatial and temporal stability of these
electrophysiological phenomena and the properties of these regions in
sinus rhythm, knowledge of which is crucial in developing an optimal
approach. We sought to investigate the spatial stability between 2
separate 30-second recordings of left and right atrial AF propagation
and the effects of increasing duration of AF recording length on the
degree of variability in mechanisms observed during simultaneous
bi-atrial mapping of atrial fibrillation. Properties of atrial regions
with the most stable patterns were explored using long and short cycle
length pacing and electroanatomic voltage mapping in sinus rhythm.
Methods