Improving Oesophageal Protection During AF Ablation

Catheter ablation is an established treatment for atrial fibrillation (AF). For those with the more longstanding form of the condition and are graded as longstanding persistent AF, catheter ablation techniques often involve an extensive ablative protocol. This often includes application of ablation energy to the posterior left atrial wall. The left atrial (LA) wall is only on average 5 millimetres away from the esophageal wall. It has been shown that ablation to the posterior LA wall can cause thermal injury to the esophageal wall. Even those that require pulmonary vein isolation only can be at risk of esophageal injury. This injury can impact on patient symptoms as well as increase the risk of an atrio-esophageal fistula being formed. Esophageal protection methods during catheter ablation for AF in current practice is very limited and investigation towards improved approaches, in the form of a randomized clinical trial is required.

The aim or purpose of this research project is to study the effect of esophageal cooling on the incidence of esophageal thermal injury (endoscopy-graded esophageal epithelial lesions and/or the presence of ablation-related gastroparesis with patient symptoms) compared to controls, after a catheter ablation procedure for the treatment of AF.

Overall design This is a randomized controlled trial with 1:1 randomization to study or control group.

Treatment/intervention plan and rationale AF patients awaiting to have a planned catheter ablation procedure as their treatment will be eligible for this study. If they participate, there is a 1:1 randomization to study or control group.

The study group will have their catheter ablation procedure with utilization of esophageal protection using the cooling tubing device (Attune Medical, Chicago IL). The cooling is controlled by the procedural doctor, with temperatures set in the range of patient safety (for example, cooling at 4 degrees). This device is already in use clinically albeit in a different clinical setting. The device is currently used an intensive care setting to provide whole body cooling. It is designed to be inserted into the esophagus. The temperature control does not allow temperatures to go into the extremes, so preserving patient safety.

The control group will have their catheter ablation procedure using standard esophageal protection methods, which is an esophageal temperature probe, to measure for any temperature changes during application of ablation energy. If measured esophageal temperatures reach beyond 38 degrees then ablation is halted in that area.

Follow up endoscopy assessment After the ablation procedure, a follow up upper GI endoscopy test will be performed to review for any ablation-related thermal injury, by a group of endoscopists who are 'blinded' to the randomization of the participant. The follow up endoscopy test will be confirmed with the participant and the timing of this follow up test is within 1 week of their catheter ablation procedure.

Clinic follow up The clinic follow up will remain exactly the same as standard care but at the first clinic (this is 12 weeks or 3 months from the ablation procedure) we will review or ask about any lingering gastro-esophageal symptoms and record this in a basic questionnaire (the GerdQ questionnaire will be used).

Eligibility Criteria:
Inclusion Criteria:

• Any AF patient planned for a catheter ablation procedure or a left atrial ablation protocol that puts them at risk of surrounding structural trauma, including oesophageal injury.

Exclusion Criteria:

* Patients at the age extremities will not be approached for the study. (Paediatric patients or young adults (\<aged 18) or older adults over the age of 85)
* Patients having simple or non-left atrial ablation procedures not needing oesophageal protection.
* Patients at high risk of oesophageal bleeding e.g. oesophageal varices.