Endo-Epi mapping of CFAE.

Rationale:

Atrial Fibrillation (AF) is the most common sustained arrhythmia. The pathophysiological mechanisms leading to onset and perpetuation of AF are still unclear. Recently, our group demonstrated dissociation of electrical activity during AF between the endocardial and epicardial layer of the atria in goats. This endo-epicardial dissociation (EED) leads to AF stabilization by providing more functional surface for fibrillation wavelets to coexist and represents a prerequisite condition for transmural conduction with reactivation of atrial myocardium in the opposing layer of the atrial wall. Demonstration of EED in humans is lacking so far.
On the other hand, new strategies are developed in treatment of AF by radiofrequency (RF) ablation. More and more, areas of Complex Fractionated Atrial Electrograms (CFAEs), supposingly involved in the perpetuation of AF, are targeted. In some clinical studies, CFAE ablation increases the success rate of RF ablation procedures to convert persistent AF to sinus rhythm. However, studies unmasking the origin and true physiological meaning of CFAEs are lacking.



Objectives:

1. To demonstrate endo-epicardial electrical dissociation (EED) in human atrial fibrillation;

2. To investigate whether occurrence of EED contributes to formation of CFAEs;

3. To study the epicardial conduction pattern above areas with endocardial CFAEs.



Study design:

Prospective non randomized observational study of consecutive patients who undergo AF ablation in the hybrid room.



Study population:

All will-competent patients admitted to the academic hospital of Maastricht for RF ablation of AF, using the ‘hybrid’approach..



Intervention:

Simultaneous endocardial and epicardial mapping of the right and left atrial free wall will be performed in all patients, in addition to standard procedure, before and after ablation.



Main study parameters/endpoints:

1. To determine the degree of EED by measuring time activation differences between the endocardial electrograms and the corresponding epicardial electrograms;

2. To correlate the degree of dissociation with the occurrence of endocardial and/or epicardial CFAEs;

3. To quantify the AF complexity in the epicardial activation pattern of areas with endocardially recorded CFAEs.



Nature and extent of the burden and risks associated with participation, benefit and group relatedness:

1. There is no direct clinical benefit expected by this observational study for enrolled patients;

2. Simultaneous endo-epicardial mapping will prolong the procedure with 15 minutes and will require introduction of a dedicated probe into the thoracic cavity;

3. An informed consent and completion of a CFR will take place preoperatively.

1. Describe concomittant electrical activation of endocardial and epicardial layers of atrium that have been shown in animal models to be dissociated, and to be involved in the perpetuation of AF;

2. Describe with a density mapping catheter the electrical pattern of Complex Fractionated Atrial Electrograms (CFAE), that are a target for Radio Frequency (RF) ablation of AF.

1. Acute study during the ablation procedure;

2. No specific follow up except that routinely carried out for AF ablation in the institution.

1. To apply a high density mapping catheter (64 poles) on the epicardial side of the atrium, facing the endocardial catheter routinely used for electrophysiological exploration of AF;

2. To compare offline the corresponding tracings.