Hidden Slow Conduction Ablation for Recurrent Atrial Fibrillation: Unmasking the Arrhythmogenic Substrate (Unmask-AF)

Hidden Slow Conduction Ablation for Recurrent Atrial Fibrillation: Unmasking the Arrhythmogenic Substrate

Over recent years, pulmonary vein isolation (PVI) procedures have demonstrated progressively enhanced efficacy and safety, resulting in a substantial increase in the number of atrial fibrillation ablations, not only as a first-line treatment but also for repeat procedures. However, there is still a notable lack of randomized evidence in this area, which limits guidance and decision-making in clinical practice. Recently, the investigators found that employing short-coupled atrial extrastimuli revealed highly fragmented or double atrial evoked electrograms (EGMs) in AF patients, termed as hidden slow conduction (HSC). Identifying HSC sites may provide insight into the early identification of the arrhythmogenic substrate, offering a potential target for ablation This multi-center, prospective, randomized, controlled trial will include two arms: one investigational (PV reconnection + HSC) and one control (PV reconnection). All the subjects will be followed for 12 months after the ablation procedure.

The aim of our study is to investigate the impact of ablating HSC sites on arrhythmia recurrence in repeat ablation procedures. The hypothesis is that the additional ablation of HSC zones may improve the freedom from atrial arrhythmia recurrence after repeat ablation procedure.

Inclusion Criteria:

• Recurrent paroxysmal AF (continuous AF episode lasting longer than 30 s but terminating spontaneously or with intervention within 7 days of onset), recurrent persistent AF (continuous AF episode lasting longer than 7 days but < 1 year) and recurrent long standing persistent AF (continuous AF ≥1 year in duration, in patients where rhythm control management is being pursued)
• Previous PVI procedure
• Age > 40 years
• Willing and capable of providing consent
• Able and willing to comply with all follow-up testing and requirements

Exclusion Criteria:

• Additional left atrial ablations during the previous procedures (es. posterior wall isolation, anterior line, roof line, CFAE and others)
• Acute illness, active systemic infection, or sepsis
• Presence of intracardiac thrombus, myxoma, tumor, interatrial baffle or patch or other abnormality that precludes catheter introduction or manipulation.
• Severe mitral regurgitation
• Women who are pregnant, lactating, or who are planning to become pregnant during the course of the clinical investigation