Substrate Guided Ablation Therapy for Atrial Fibrillation

Study Overview
=================
Brief Summary
-----------------
Atrial fibrillation (AF), often referred to as an 'irregular heartbeat', is the most common abnormal heart rhythm worldwide. AF may be intermittent (termed paroxysmal) or sustained (termed persistent).Catheter ablation is increasingly being used to manage individuals with AF, however in a significant proportion of cases AF recurs. Such rhythm control interventions are known to be less effective in individuals with persistent AF compared with those with paroxysmal AF. Analysis of heart tissue of individuals with AF show deposition of scar tissue within the heart muscle and this scar tissue promotes abnormal electrical activity that is involved in causing AF. The aim of the proposed study is to evaluate the feasibility and effectiveness of combining conventional pulmonary vein isolation (PVI) during catheter ablation for AF with adjunctive substrate ablation.

Detailed Description
-----------------
This is a single-centre, non-randomized study investigating the feasibility, safety and efficacy of substrate guided ablation in persistent AF. The study population will be patients between the ages of 18 and 80 with symptomatic, persistent atrial fibrillation (≥1 year) referred for catheter ablation on standard clinical grounds. The catheter ablation procedure will be performed using the Precision Ensite™ three dimensional mapping system and the Advisor High Density Grid™ mapping catheter (Abbott Medical Incorporated). All patients will undergo conventional pulmonary vein isolation (PVI). As an adjunctive strategy to PVI, low voltage areas (used as a surrogate for atrial scar), as derived from the voltage map, will be targeted for ablation in order to isolate or homogenise these areas of the atrium. A pre-procedural cardiac magnetic resonance imaging scan will be performed in all patients. All patients will undergo 12 months follow-up with an ECG and ambulatory holter monitoring at 3, 6 and 12 months.

Official Title
-----------------
High Density Substrate Evaluation and Guided Ablation Therapy for Atrial Fibrillation

Conditions
-----------------
Persistent Atrial Fibrillation

Intervention / Treatment
-----------------
* Procedure: Substrate guided left atrial ablation


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Patients aged ≥18 years and ≤ 80 with a clinical indication for persistent atrial fibrillation ablation Exclusion Criteria: Contraindication to anticoagulation Thrombus in the left atrium despite anticoagulation Cerebrovascular accident within the previous 6 months Patients actively participating in another research study will be not be permitted to enrol. Patients who have been involved with other research studies will be able to participate after a minimum period of 3 months after completion of prior study follow up Females of childbearing potential must have a negative pregnancy test on the day of the ablation procedure due to the radiation exposure during the procedure

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Substrate guided intervention arm<br>Participants recruited to the study will undergo High Density Wave Solution™ guided substrate mapping of the left atrium. Ablation will thereafter be performed to comprise wide area circumferential ablation of the pulmonary veins in pairs, followed by ablation of low voltage zones in the left atrium. | Procedure: Substrate guided left atrial ablation<br>* Ablation therapy targeting areas of low voltage, which may include encirclement, homogenization or targeting of abnormal electrograms and anchored to a non-conducting structure if the region is in close proximity or likely to create an isthmus for arrhythmias.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Freedom from atrial arrhythmias (>30 seconds) after a single procedure without anti-arrhythmic drugs (AADs) within 12 months, measured by ambulatory holter monitoring | All participants will have an ECG and ambulatory holter monitor performed at 3, 6 and 12 months after the procedure. | 12 month | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To compare 1-year arrhythmia free clinical outcome with historical control patients matched by propensity score | Freedom from AF defined as no documented AF (>30 seconds) following the 3 months blanking period following a single procedure, off anti-arrhythmic drugs. | 12 Months | 
| Safety endpoint evaluating the incidence of intraprocedural (primarily Advisor High Density Grid™ mapping catheter) related adverse events |  | 12 Months | 
| To correlate cardiac MRI derived scar distribution and burden in the left atrium with the baseline voltage map obtained using the Advisor High Density Grid™ catheter | The left atrium will be segregated into pre-defined regions and marked for presence or absence of fibrosis as identified on MRI scans and low voltage identified on invasive mapping. Inter-class correlation will performed to evaluate consistency between modalities. | 12 Months | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Atrial fibrillation, Catheter Ablation, Substrate