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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

Status
Not yet recruiting
Phases
NA
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT06657170
Enrollment
212
Registered
2024-10-24
Start date
2024-12-31
Completion date
2027-09-30
Last updated
2024-12-12

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Atrial Fibrillation

Keywords

Catheter Ablation, Re-do Procedures, Hidden Slow Conduction, Functional Substrate Ablation

Brief summary

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.

Interventions

PROCEDUREPulmunary veins reconnection plus hidden slow conduction ablation

Ablation of pulmonary veins reconnections plus the search and ablation of hidden slow conductions sites (HSC) in the left atrium. HSC sites are defined as EGMs showing highly fragmented or double electrograms in response atrial triple extrastimulus, presenting normal or fractionated electrogram in the sinus rhythm. After checking for PV's conduction breakthroughs, point-by point ablation targeting HSC-EGMs will be performed. The end point for HSC+ ablation will be reached with loss of local capture at a given lesion, pacing from the ablation catheter at high output (10V·2ms).

PROCEDUREPulmunary veins (PV) reconnection ablation only

Each vein will be re-assessed by observing PV potentials along the PV ostia and by pacing from the distal bipole of the ablation catheter (10mA at 2ms) within the lesion set with failed capture of the left atrium. In case of PVs reconnection touch-up applications will be performed at the earliest potential site, identified by comparing far-field atrial EGM to near-field local EGM timing, until isolation will be achieved (entrance and exit block).

Sponsors

Centro Medico Teknon
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Intervention model description

This is a two-arm, single-center, randomized controlled trial

Eligibility

Sex/Gender
ALL
Age
40 Years to No maximum
Healthy volunteers
No

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

Design outcomes

Primary

MeasureTime frameDescription
Atrial arrhythmias recurrenceup to 12 mothsThe primary endpoint of the study aims to establish the impact of targeting HSC sites alongside PV gaps in repeat ablation procedures for patients with recurrent AF. Specifically evaluating the freedom from atrial tachyarrhythmia recurrence (documented AF/AT/AFL lasting at least 30s).

Secondary

MeasureTime frameDescription
incidence of periprocedural complications (pericardial effusion)up to 12 monthsincidence of periprocedural complications such as pericardial effusion
Use of antiarrhythmic drugsup to 12 monthsUse of antiarrhythmic drugs after the blanking period of 60 days.
incidence of periprocedural complications (peripheral complication)up to 12 mothsincidence of periprocedural complications such as peripheral complication
incidence of periprocedural complications (transient ischemic attack or stroke)up to 12 monthsincidence of periprocedural complications such as transient ischemic attack or stroke
Burden of atrial arrhythmiasup to 12 mothsArrhythmic burden (average percentage of time in AF/AT in 24h Holter)

Other

MeasureTime frameDescription
procedure timesup to 12 monthsradiofrequency (RF) total delivery time
Concentration of intramyocardial fat (inFAT) into the HSC pointsup to 12 monthsConcentration of intramyocardial fat (inFAT) into the atrial area where we found the HSC points
Procedure featuresup to 12 monthsprocedure time
Atrial arrhythmias first recurrenceup to 12 monthsEvaluation of the atrial arrhythmias recurrence in patients with isolated PVs underwent HSC sites ablation
Left atrial wall thickness (LAWT) measurement into the HSC pointsup to 12 monthsLeft atrial wall thickness (LAWT) measurement into the atrial areas where we found the HSC points
procedure featuresup to 12 monthsfluoroscopy time

Contacts

Primary ContactAntonio Berruezo Sanchez, MD, PHD
antonio.berruezo@quironsalud.es3384090290

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026