Assessment of Catheter Tissue Contact in PFA (ASSESS PFA)

Assessment of Electrode-tissue Contact and Pulmonary Vein Isolation Durability After Pulsed Field Ablation With a Circular "Single Shot" Catheter in Patients With Paroxysmal Atrial Fibrillation

Pulmonary vein isolation remains the cornerstone of invasive treatment for atrial fibrlllation. Despite recent technological advances in the field of pulsed field ablation (PFA) pulmonary vein isolation durability and arrhythmia free success rates remain approximately at the level of previous years and the radiofrequency ablation era.

Isolation durability during PFA procedures might be enhanced by:

1. Intraprocedural monitoring contact of catheter electrode to atrial tissue.
2. Intraprocedural assessment of the transmurality of irreversible electroporation lesion.

The aim of our study is to use intracardiac electrogram (iEGM) based analysis for assessment of catheter-tissue contact and PFA lesion durability.

Study Overview

• Status: Not yet recruiting
• Conditions: Atrial Fibrillation (AF)
• Intervention / Treatment: Device: Electrode tissue contact assessment during pulsed field ablation

Detailed Description

Study design: single group, prospective, observational study. Inclusion criteria and eligibility: patients with paroxysmal atrial fibrillation referred to our center for catheter ablation in accordance with EHRA guidelines and with signed written consent for participation in the study.

Study group: 60 patients divided in two groups. Group 1: initial 10 patients that will have the PFA procedure performed as is stated under Group 1 in the Procedural Protocol section.

Group 2: next 50 patients that will have procedural protocol defined after analysis of procedures in the initial 10 patients.

Procedural protocol:

all patients will have a contrast enhanced computer tomography (CTA) scan of the left atrium performed before the ablation procedure. CTA based left atrial 3D reconstruction will be created with a dedicated segmentation software and fused with the 3D model of the left atrium created during the procedure using the 3D electroanatomical mapping (EAM) system.

Procedures will be performed in deep sedation, using 3D EAM system and intracardiac echocardiography. PFA applications per vein and per antrum will be delivered as specified and recommended by Medtronic. After full lesion set high density mapping of pulmonary veins, venous ostia and antral regions for signs of acute conduction gaps and residual (dormant) conduction within isolation lines will be performed.

Group 1: will include the first 10 patients. First PFA applications per side (left or right) will be delivered in a manual mode (4 manual applications per one full set). An intracardiac electrocardiogram (iEGM) recording period of 30 seconds will be used before the start of applications and a 2 minute iEGM recording period will be used after each of the 4 manual applications with the ablation catheter left in place during the recording. After the first application on each side, applications will be switched to automatic mode and a iEGM recording period of 2 minutes will be used after each automatic application with 30 seconds recording used as the baseline. Recording will include bipolar and unipolar iEGMs. Total number of applications will 32, 4 ostial and 4 antral per vein.

Group 2: will include additional 50 patients. Mode of iEMG recording (bipolar, unipolar, filter settings) and recording time will differ from Group 1 and will be specified based on analysis and correlation of iEGM recordings with acute and longterm conduction gaps.

In this group additional PFA applications will be delivered at ostial/antral regions that will harbor potentially insufficient (nontransmural irreversible electroporation) lesions according to analysis and correlation of iEGM recordings with acute and longterm conduction gaps.

Follow-up (Group 1 and 2) At 6-8 weeks after the procedure all patients will undergo a mandatory reassessment procedure with high density mapping of veins, venous ostia and antral regions for signs of longterm conduction gaps. Any conduction gaps and residual (dormant) conduction within isolation lines will be recorded and tagged on the 3D EAM maps.

Patients will be followed at the outpatient clinic at 3, 6 and 12 months with 7-day holter ECG recordings at each visit.

Outcome measures

1. Assessment of contact (electrode - tissue) based on analysis of intraprocedural characteristics and acute changes of bipolar iEGMs.
2. Assessment of PFA lesion durability based on analysis of intraprocedural characteristics and changes of unipolar iEGMs and information about the presence of conduction gaps from mandatory reassessment procedures.

Study will be conducted in two phases

Phase 1 (duration 1 year):

Obtaining approval of Medical ethics committee Enrolment of 10 patients (group 1) with remap at 6-8 weeks

Phase 2 (duration 2 years) with 1 year follow-up in an out-patient clinic using 7-day holter ECG recordings at 3, 6 and 12 months

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Tine Prolič Kalinšek, MD; Phone Number: 0038615228238; Email: tine.prolic.kalinsek@kclj.si
• Study Contact Backup: Name: Matevž Jan, MD, PhD; Phone Number: 0038615228238; Email: matevz.jan@kclj.si

Study Locations

• Slovenia
  • Ljubljana, Slovenia, 1000
    • University Medical Centre Ljubljana
    • Contact: Matevž Jan, MD, PhD; Phone Number: 0038615228238; Email: matevz.jan@kclj.si
    • Sub-Investigator: Jernej Štublar, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patients with electrocardiographically documented paroxysmal atrial fibrillation (AF), defined according to the European Heart Rhythm Association (EHRA) guidelines

Exclusion Criteria:

• Contraindication to pulsed field ablation in the left atrium (e.g., presence of a left atrial appendage occlusion device).
• Contraindication to undergoing the procedure under general anesthesia.
• Age >80 years.
• Markedly enlarged left atrium (diameter >50 mm on echocardiography, LAVI >50 mL/m²).
• Life expectancy <1 year.
• Acute life-threatening illness.
• Presence of left atrial thrombus.
• Secondary atrial fibrillation.
• Previous left atrial ablation.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Catheter - tissue contact assessment; Assessment of contact between electrodes on the pulsed field ablation (PFA) catheter and left atrial wall will be made based on change of bipolar intracardiac electrograms (iEGM) after first PFA delivery.

Device: Electrode tissue contact assessment during pulsed field ablation; Pulsed field ablation (PFA) catheter electrode - tissue contact assessment based on analysis of bipolar intracardiac electrocardiograms: a multipolar PFA catheter will be used for pulmonary vein isolation in a manual mode, which means that instead of delivering fully therapeutic four ablative high voltage pulse trains at each location around pulmonary veins, each of those pulse trains will be delivered manually. Changes (voltage, shape,...) in bipolar intracardiac electrocardiograms (iEGM) measured with ablative catheter electrodes will be assessed after each manual pulse train delivery.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Assessment of contact	Assessment of contact (electrode - tissue) based on analysis of intraprocedural characteristics and acute changes of bipolar iEGMs: when bipolar iEGM voltage amplitude will decrease significantly after first manual ablative pulse train delivery the contact will be considered as good, in contrast to no or minimal change in bipolar iEGM amplitude when contact will be considered as poor.	During index procedure.
Assessment of PFA lesion durability	Assessment of PFA lesion durability based on analysis of intraprocedural characteristics and changes of unipolar intracardiac electrocardiograms (iEGM). Additionally to bipolar iEGM changes during index procedure for used for contact assessment also the unipolar iEGM changes will be followed with an assumption that prolonged and unchanged increased unipolar iEGM amplitude after PFA delivery at each location correlates with transmural PFA lesion formation that leads to durable ablation lesions and durable pulmonary vein isolation.This durability of ablation lesions and pulmonary vein isolation will be assessed at mandatory reassessment procedures (remapping procedures with a high-density mapping catheter).	From index procedure until 6-8 week mandatory reassessment procedure.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Recurrence of arrhythmia	Recurrence based on registration of 30 second or longer episodes of atrial fibrillation/atrial flutter/atrial tachycardia on 7-day holter electrocardiogram or arrhythmia recorded on 12-lead surface electrocardiogram at 3, 6 and 12 monthy after index procedure. If available, additional symptom driven holter ECG or 12-lead electrocardiogram recordings will be used for analysis.	From index procedure until completed 12 month follow-up.

Collaborators and Investigators

• Sponsor: University Medical Centre Ljubljana
• Collaborators: Medtronic
• Investigators: Study Chair: Damijan Miklavčič, PhD, University of Ljubljana

Study record dates

Study Major Dates

• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): September 1, 2028
• Study Completion (Estimated): September 1, 2028

Study Registration Dates

• First Submitted: July 14, 2026
• First Submitted That Met QC Criteria: July 18, 2026
• First Posted (Actual): July 23, 2026

Study Record Updates

• Last Update Posted (Actual): July 23, 2026
• Last Update Submitted That Met QC Criteria: July 18, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Atrial Fibrillation; Pulsed field ablation; Intracardiac electrogram; Pulse Select; Contact assessment
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Arrhythmias, Cardiac; Pathological Conditions, Signs and Symptoms; Atrial Fibrillation
• Other Study ID Numbers: ASSESS PFA

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: IPD used in results for publication.
• IPD Sharing Time Frame: 1.9.2026-1.9.2028
• IPD Sharing Access Criteria: Upon request with a proposal that describes planned analyses and anticipated results. Request must be made directly to the Principal investigator using contact information. Requests will be reviewed by the Principal investigator and Study chair.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: Yes