Diverse activation patterns during persistent atrial fibrillation by noncontact charge‐density mapping of human atrium

Abstract

Background Global simultaneous recording of atrial activation during atrial fibrillation (AF) can elucidate underlying mechanisms contributing to AF maintenance. A better understanding of these mechanisms may allow for an individualized ablation strategy to treat persistent AF. The study aims to characterize left atrial endocardial activation patterns during AF using noncontact charge‐density mapping. Methods Twenty‐five patients with persistent AF were studied. Activation patterns were characterized into three subtypes: (i) focal with centrifugal activation (FCA); (ii) localized rotational activation (LRA); and (iii) localized irregular activation (LIA). Continuous activation patterns were analyzed and distributed in 18 defined regions in the left atrium. Results A total of 144 AF segments with 1068 activation patterns were analyzed. The most common pattern during AF was LIA (63%) which consists of four disparate features of activation: slow conduction (45%), pivoting (30%), collision (16%), and acceleration (7%). LRA was the second‐most common pattern (20%). FCA accounted for 17% of all activations, arising frequently from the pulmonary veins (PVs)/ostia. A majority of patients (24/25; 96%) showed continuous and highly dynamic patterns of activation comprising multiple combinations of FCA, LRA, and LIA, transitioning from one to the other without a discernible order. Preferential conduction areas were typically seen in the mid‐anterior (48%) and lower‐posterior (40%) walls. Conclusion Atrial fibrillation is characterized by heterogeneous activation patterns identified in PV‐ostia and non‐PV regions throughout the LA at varying locations between individuals. Clinical implications of individualized ablation strategies guided by charge‐density mapping need to be determined.

Substrate mapping of the left atrium in persistent atrial fibrillation: spatial correlation of localized complex conduction patterns in global charge-density maps to low-voltage areas in 3D contact bipolar voltage maps

“…During the UNCOVER post-market clinical study [17], distinct LCC patterns, as previously described by Chi et al [9] in PsAF, were observed and categorized in all 129 subjects. To the best of our knowledge, the relationship between these LCC pattern-cores and LVAs identified by BVM had not been investigated previously.…”

“…Activation maps of PsAF were acquired by AcM, previously described in detail by Shi et al [9]. In summary, AcM provides maps of electrical activation across an ultrasoundacquired cardiac chamber surface.…”

“…Furthermore, BV amplitude is dependent on rate and directionality of the conduction wave front [8]. Application of a global, non-contact, charge-densitybased imaging, and mapping system (AcQMap, Acutus Medical, Carlsbad CA) (AcM) in PsAF has led to the identification of distinct localized complex conduction (LCC) patterns that may be relevant in the initiation and maintenance of PsAF [9]. These patterns have been classified as focal, characterized by early activation that did not generate from previous cardiac wavefronts; localized rotational activation (LRA) patterns, characterized by wavefront propagation rotating around a central obstacle; and localized irregular activity (LIA) in which the activation pattern displays repetitive, multidirectional, entry, exit, and pivoting conduction through and around a confined isthmus-like zone.…”

Is There Rule to the Chaos: Defining Stable Patterns in Atrial Fibrillation

“…AcQMap also described a new repetitive pattern which is an attempt to spatially localize fibrillatory conduction called localized irregular activation (LIA). In recent studies, this has been subdivided into four potentially underlying mechanisms based on propagation patterns (Figure 1) 7 . However much work needs to be done to better translate these studies into useful targets for additional ablation beyond the pulmonary veins.…”

Editorial to “Diverse activation patterns during persistent atrial fibrillation by non‐contact charge‐density mapping of human atrium”

“…A preliminary study demonstrated that the dipole density (unit, μCoulombs/cm) represents an actual biophysics of cardiac activity that is sharper and narrower than the voltage, so that it can provide a more discrete wavefront propagation 4 . In this issue of the Journal , Rui Shi et al retrospectively analyzed and characterized activation patterns of persistent AF using this system 5 . The main findings described in this paper were as follows: (a) Persistent AF is characterized by highly dynamic and heterogeneous activation patterns consisting of localized irregular activation (LIA) (63%), localized rotational activation (LRA) (20%), and focal with centrifugal activation (FCA) patterns (17%); (b) a combination of slow/accelerated conduction, pivotal activation, and collisions were observed; (c) preferential conduction areas with repetitive LRA and LIA were detected in the mid‐anterior (48%) and lower‐posterior (40%) LA wall; and (d) observations of transitions between LIA and LRA with merging and breaking of wavefronts were noted.…”