Assessment of Catheter Tissue Contact in PFA (ASSESS PFA)

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