Wavefront Field Mapping Reveals a Physiologic Network Between Drivers Where Ablation Terminates Atrial Fibrillation

Abstract

Background: Localized drivers are proposed mechanisms for persistent atrial fibrillation (AF) from optical mapping of human atria and clinical studies of AF, yet are controversial because drivers fluctuate and ablating them may not terminate AF. We used wavefront field mapping to test the hypothesis that AF drivers, if concurrent, may interact to produce fluctuating areas of control to explain their appearance/disappearance and acute impact of ablation. Methods: We recruited 54 patients from an international registry in whom persistent AF terminated by targeted ablation. Unipolar AF electrograms were analyzed from 64-pole baskets to reconstruct activation times, map propagation vectors each 20 ms, and create nonproprietary phase maps. Results: Each patient (63.6±8.5 years, 29.6% women) showed 4.0±2.1 spatially anchored rotational or focal sites in AF in 3 patterns. First, a single (type I; n=7) or, second, paired chiral-antichiral (type II; n=5) rotational drivers controlled most of the atrial area. Ablation of 1 to 2 large drivers terminated all cases of types I or II AF. Third, interaction of 3 to 5 drivers (type III; n=42) with changing areas of control. Targeted ablation at driver centers terminated AF and required more ablation in types III versus I ( P =0.02 in left atrium). Conclusions: Wavefront field mapping of persistent AF reveals a pathophysiologic network of a small number of spatially anchored rotational and focal sites, which interact, fluctuate, and control varying areas. Future work should define whether AF drivers that control larger atrial areas are attractive targets for ablation.

Linking Electrical Drivers With Atrial Cardiomyopathy for the Targeted Treatment of Atrial Fibrillation

“…The exact type of organization is a topic of controversy, as some groups have proposed that AF is maintained via dissociated endo-epicardial breakthroughs (de Groot et al, 2010) or focal or rotational drivers (Jalife, 2003;Baykaner et al, 2014;Haissaguerre et al, 2014;Lalani et al, 2014;Schricker et al, 2014;Hansen et al, 2015Hansen et al, , 2017Hansen et al, , 2018Quintanilla et al, 2016;Zahid et al, 2016;Csepe et al, 2017;Nattel et al, 2017;Zhao et al, 2017). Recent seminal work has demonstrated that rotational and focal drivers exist at sites that terminate AF when ablated, reinforcing the role of organized drivers maintain (Zhao et al, 2017;Kowalewski et al, 2018;Zaman et al, 2018;Leef et al, 2019).…”

“…A promising technique was recently proposed using wavefront field mapping (Leef et al, 2019) to reveal organized areas of control during AF (Figures 9A,B). This novel vector mapping method computes activation times to calculate phase ( Figure 9C), activation fronts, and gradient matching to display the vector fields ( Figures 9D-F) to describe propagation of these fronts.…”

“…An advantage of this method is the ability to identify regions that control larger areas of the atria during AF, and thus distinguish true driver of AF compared to passive organized areas. This concept was studied retrospectively in 54 patients (Leef et al, 2019) in whom ablation of proposed drivers (from phase mapping) terminated AF, and all sites that were found to control larger atrial areas terminated AF with ablation. Prospective studies are ongoing to evaluate the ability of this method to identify critical drivers of AF to improve the targeted therapy of AF.…”

Toward Mechanism-Directed Electrophenotype-Based Treatments for Atrial Fibrillation

“…By testing for causal relationships of electrical signals between neighboring regions of the heart over time and quantifying the number of causal relationships above a set “causality threshold,” we can reliably measure global fibrillation organization and characterize the AF electrophenotype, even when applied to low spatial resolution clinical AF data ( Figure 2 ). Other novel analysis approaches, such as wavefront field mapping, which can reveal the network of rotational and focal sites in AF ( Leef et al, 2019 ), electrocardiographic flow mapping, which determines the main propagation patterns during AF ( Bellmann et al, 2019 ), or mapping of connectivity between different regions of the atria usual mutual information analysis ( Tao et al, 2017 ), may also be able to identify the AF electrophenotype to guide mechanism-directed treatments.…”

The interconnected atrium: Acute impact of pulmonary vein isolation on remote atrial tissue

“…ECGi also focuses on short periods between QRS complexes (1228 ± 56 ms) which inherently limits the stability of any identified feature, and the use of adenosine may alter AF 21 . Further analysis should ultimately extend beyond phase singularities and current studies are examining whether the spatial areas of organized features 22 or their rate 9 may indicate a hierarchy of relatively more or less important sites to AF.…”