Abstract
Electrical activation during atrial fibrillation (AF) appears chaotic and disorganised, which impedes characterisation of the underlying substrate and treatment planning. While globally chaotic, there may be local preferential activation pathways that represent potential ablation targets. This study aimed to identify preferential activation pathways during AF and predict the acute ablation response when these are targeted by pulmonary vein isolation (PVI). In patients with persistent AF (n = 14), simultaneous biatrial contact mapping with basket catheters was performed pre-ablation and following each ablation strategy (PVI, roof, and mitral lines). Unipolar wavefront activation directions were averaged over 10 s to identify preferential activation pathways. Clinical cases were classified as responders or non-responders to PVI during the procedure. Clinical data were augmented with a virtual cohort of 100 models. In AF pre-ablation, pathways originated from the pulmonary vein (PV) antra in PVI responders (7/7) but not in PVI non-responders (6/6). We proposed a novel index that measured activation waves from the PV antra into the atrial body. This index was significantly higher in PVI responders than non-responders (clinical: 16.3 vs. 3.7%, p = 0.04; simulated: 21.1 vs. 14.1%, p = 0.02). Overall, this novel technique and proof of concept study demonstrated that preferential activation pathways exist during AF. Targeting patient-specific activation pathways that flowed from the PV antra to the left atrial body using PVI resulted in AF termination during the procedure. These PV activation flow pathways may correspond to the presence of drivers in the PV regions.
Highlights
Patients with persistent atrial fibrillation (AF) are a diverse population
Simulation data corresponding to an right atrium (RA) atrial flutter is shown in Figure 3A with wavefront propagation from the inferior vena cava (IVC) along the septal wall to the RAA and superior vena cava (SVC), which propagated along the lateral wall from the RAA and the SVC to the IVC
A re-entrant pattern is visible on the roof of the right atrium because there is a driving pattern around the tricuspid valve (TV) that propagated along the septal wall from the IVC to SVC, and along the lateral wall from the SVC to the IVC
Summary
Some patients with persistent AF require multiple catheter ablation procedures with more extensive ablation strategies, which may still be unsuccessful, while for other patients, isolation of the pulmonary veins (PVs) is a sufficient treatment approach (Verma et al, 2015). Identifying appropriate ablation strategies for specific patients with persistent AF, including stratifying patients for whom pulmonary vein isolation (PVI) will be sufficient treatment, remains a clinical challenge (Johner et al, 2019). If solved, this could lead to improved safety and better patient selection, as well as decreased time and cost for procedures. We further hypothesised that the features of these activation pathways can be used to predict PVI ablation response
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