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