Relationship Between the Posterior Atrial Wall and the Esophagus: Esophageal Position and Temperature MEasurement During Atrial Fibrillation Ablation.

A multimodal strategy integrating esophageal visualization with the multidetector computed tomography (MDCT) and simultaneous temperature monitoring has never been put into practice. We have developed an isodistance map (esophageal print) to depict the atrio-esophageal relationship and to analyze the esophageal position peri procedurally. The present randomized study intends to analyze the usefulness of the esophageal print in predicting local thermal heating of the esophagus.

Primary objective: to validate the usefulness of the esophageal print in avoiding temperature rises caused by radiofrequency (RF) application at the left atrial (LA) posterior wall during atrial fibrillation ablation

Secondary objectives:

1. to establish if there is a linear relationship between intraesophageal temperature rise and atrio-esophageal distance as calculated by the MDCT-derived esophageal print.
2. to analyze the need for ablation line modification.
3. to analyze the need for energy (power settings, ablation index, ablation time, etc.) modification.
4. to develop a new multimodal approach to esophageal monitoring during AF/AT ablation.

Interventions

1. Pre-procedural scan and Esophageal Isodistance Print

   The methods for the acquisition of the cardiac MDCT and the image processing have been described in Part 1. During the segmentation process, the epicardial layer of the posterior atrial wall and the esophageal wall have been defined. The distance between these two structures is computed at each epicardial point, allowing to create an esophageal print on top of the epicardial layer. The isodistance color map uses a color scale to depict a range of distance; red being the closest (\< 1 mm) and purple being the most distant (\> 4 mm). Yellow, green and blue will be considered the intermediate values.
2. Luminal esophageal temperature (LET) monitoring

   A multi-thermocouple temperature probe (SensiTherm, St. Jude Medical, Inc., St. Paul, MN, USA) will be advanced via transnasal or transoral access into the esophagus once the patient is under general anesthesia. When the esophageal print is close to the ablation line, the temperature probe position will be adjusted under fluoroscopic guidance before application at each pair of pulmonary veins to ensure that it overlaps the ablation line. All esophageal temperature rises above 39 °C will be documented and RF application will be stopped.
3. Pulmonary vein ablation lines regarding Esophageal Isodistance Print

Before randomization, an investigator blinded to the esophageal position will draw the PVI ablation line around both pairs of veins based on the type of AF (closer to the ostium for paroxysmal AF and wider for persistent AF).

Eligibility Criteria:
Inclusion Criteria:

* Age \> 18 years.
* Indication for any atrial fibrillation or left atrial flutter ablation procedure.
* Documented episodes of atrial arrhythmia (AF/AT/AFL)
* Signed informed consent.

Exclusion Criteria:

* Age \< 18 years.
* Pregnancy.
* Impossibility to perform CT Scan.
* Impossibility to perform transesophageal echocardiography or to insert esophageal temperature monitoring probe.
* Concomitant investigation treatments.
* Medical, geographical and social factors that make study participation impractical
* Inability to give written informed consent.
* Patient's refusal to participate in the study.