Use of a High Density Mapping System to Complete Wide Area Circumferential Ablation of the Pulmonary Veins and Avoid Ostial Segmental Ablation

Atrial Fibrillation Clinical Trial

— HD-WACA  

Official title:

Use of a High Density Mapping System to Complete Wide Area Circumferential Ablation of the Pulmonary Veins and Avoid Ostial Segmental Ablation

Clinical Trial Details — Status: Terminated

Administrative data

• NCT number: NCT02917044
• Other study ID #: 15HH2466
• Status: Terminated
• Phase: N/A
• Start date: March 2016
• Est. completion date: June 2018

Study information

• Verified date: October 2019
• Source: Imperial College Healthcare NHS Trust
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

This is a prospective, multicentre, randomized single blind, parallel group study to be conducted in the UK (2 sites).Approximately 48 patients will be recruited aiming for 40 eligible for randomization. The study is designed to compare the operator's best attempt at WACA completion with and without Rhythmia guidance

Description:

BACKGROUND Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia occurring in 1-2% of the general population. AF can be associated with debilitating symptoms and confers an increased risk of death, stroke, heart failure and hospitalization. As such there is a need for effective therapies for AF. In particularly catheter based therapies, which can limit the need for chronic drug therapy, are becoming more widely accepted.

The development of AF requires both a trigger and susceptible substrate. Ectopic activity originating within the pulmonary veins (PVs) is a widely recognised factor in the genesis of paroxysmal AF, whilst electrical, contractile and structural remodelling of atrial myocardium are each important contributing factors to the arrhythmogenic substrate in AF.

An early strategy in paroxysmal AF (PAF) was to target ectopic triggers coming from the PV via ostial segmental ablation (OSA). Here radiofrequency (RF) ablation was applied close to the PV ostia at sites of early signals, usually until PVs were electrically isolated from the left atrium (LA). This approach resulted in a success rate, with regard to freedom from AF after a single procedure, of 65-90% after 1 year but closer to 50% after 5 years. The recognition of PV stenosis as a complication of RF delivery within a PV, as well as the recognition that initiation sites could be located in the antrum led to a shift in ablation strategy towards wider encirclement of the PVs using wide area circumferential ablation (WACA) using electroanatomical mapping to guide RF delivery. This resulted in improved success rates in a head-to-head comparison with OSA and it is possible that this relates to substrate modification inherent in this approach.

Recurrence of AF remains problematic following ablation. Pulmonary vein reconnection after ablation is thought to contribute to the majority of recurrent episodes of AF in paroxysmal AF. Electrical isolation of the PVs is often not achievable with WACA alone - 95% of patients had residual connections following WACA alone in one study. Most clinicians at this juncture will look for any obvious gaps in the line and ablate if there are early PV signals. If this is unsuccessful then it is often necessary to resort to OSA to achieve PV isolation. In essence a large proportion of PV isolation procedures, which started with a WACA strategy, are in fact a hybrid of WACA and OSA. This both has the potential to increase the complication rate by risking PV stenosis and reducing efficacy through omitting important substrate modification and allowing residual connection of part of the antrum and the LA.

The introduction of Rhythmia, a novel electroanatomical mapping system with the potential to rapidly acquire high density electroanatomical data, may allow an alternative strategy and more efficient targeting of gaps in WACA lines. The pilot data shows that the system is particularly adept in assessing gaps in ablation lines including WACA lines. Mapping and targeting such gaps may hold the key to efficiently completing PV isolation after an initial WACA line is performed.

RATIONALE FOR CURRENT STUDY Research Question: Can ostial segmental ablation be avoided during a wide area circumferential ablation (WACA) by using the Rhythmia high density mapping system? Hypothesis: The current study is designed to test the hypothesis that high density mapping using Rhythmia can enhance the operator's ability to electrically isolate PVs without unnecessary excessive ablation or OSA

Recruitment information / eligibility

• Status: Terminated
• Enrollment: 17
• Est. completion date: June 2018
• Est. primary completion date: March 2018
• Accepts healthy volunteers: No
• Gender: All
• Age group: 18 Years to 80 Years

Eligibility

Inclusion Criteria:

• ECG documented AF

• Listed for AF ablation by referring physician

• Planned ablation includes a first-time PVI.

• Patient signed informed consent form

Exclusion Criteria:

• Age <18 or >80

• LA diameter >60mm

• AF secondary to transient correctible abnormalits (e.g. electrolyte imbalance, thyrotoxicosis, recent infective or inflammatory process)

• Intra-atrial thrombus or tumour

• Renal failure requiring haemodialysis

• Heart failure with NYHA III-IV or EF<35%

Related Conditions & MeSH terms

• Atrial Fibrillation

Intervention

Procedure:
• Atrial Fibrillation Ablation
Procedure involving catheter ablation to produce pulmonary vein isolation. Pulmonary veins are isolated by assessing electrograms circumferentially around the PV using the Orion catheter.

Device:
• Catheters used to isolate pulmonary veins
Catheters transiently inserted into body via femoral veins in order to produce pulmonary vein isolation. These catheters are the same in each arm and comprise the Orion catheter (Boston Scientific) and the Tacticath (St Jude) which are used to produce pulmonary vein isolation and which are approved for use in standard EP procedures by the relevant authorities (CE marked). It is merely the protocol by which they are used that iffers in the two arms.

Procedure:
• Atrial Fibrillation Ablation with HD mapping to isolate PVs
Procedure involving catheter ablation to produce pulmonary vein isolation. Pulmonary veins are isolated by use of electroanatomical mapping with the Orion catheter around the sites ablation in order to target points of breakthrough.

Device:
• Rhythmia HD mapping
Mapping activation patterns using the Rhythmia system in conjunction with the Orion catheter

Locations

Country	Name	City	State
United Kingdom	Hammersmith Hospital	London	Please Select Region, State Or Province

Sponsors (2)

Lead Sponsor	Collaborator
Imperial College Healthcare NHS Trust	Boston Scientific Corporation

Country where clinical trial is conducted

United Kingdom, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Total time in minutes required to produce isolation of veins per WACA	Following first pass ablation with WACA, if either vein is not isolated the patient will be randomized into group A or B. The total RF time taken to isolate the veins for that WACA will be measured as one of 2 joint primary outcome measures.	Procedural - i.e. assessed over procedure duration only (about 3 hours)
Primary	Total number of radiofrequency ablation lesions to produce isolation of veins per WACA	Following first pass ablation with WACA, if either vein is not isolated the patient will be randomized into group A or B. The total number of lesions (each lesion being 30s in duration) to isolate the veins for that WACA will be measured as one of two joint primary outcome measures.	Procedural - i.e. assessed over procedure duration only (about 3 hours)
Secondary	Whether ostial ablation is required in each case (Yes/No)	This is a measure of whether ostial ablation (undesirable) will be required (yes/no). It is assessed during procedure.	Procedural - i.e. assessed over procedure duration only (about 3 hours)
Secondary	Number of radiofrequency ablation lesions required within the WACA lesion set	The number of oostial lesions required in each case (number of ablation lesions)	Procedural - i.e. assessed over procedure duration only (about 3 hours)
Secondary	Total radiofrequency ablation time (in mins) within the WACA lesion set	This is the total ablation time (in mins) within the WACA required to produce PV isolation	Procedural - i.e. assessed over procedure duration only (about 3 hours)
Secondary	Total number of radiofrequency ablation lesions required to produce PV isolation per patient	As per primary endpoint but on a per patient rather than per vein basis	Procedural - i.e. assessed over procedure duration only (about 3 hours)
Secondary	Total procedural time (in mins) required to produce PV isolation	Whether procedure time (in mins) is different in group A vs group B	Procedural - i.e. assessed over procedure duration only (about 3 hours)
Secondary	Percentage of patients with successful PV isolation	Proportion of veins successfully isolated with the contrasting techniques	Procedural - i.e. assessed over procedure duration only (about 3 hours)
Secondary	Percentage of patients suffering symptomatic PV stenosis	Proportion of patients coming back within 3 months with symptomatic PV stenosis	3 months
Secondary	Percentage of patients with AF recurrence	Proportion of patients remaining AF free at 3 months as analysed per Kaplan-Meier format	3 months