RF Power, LSI and Oesophageal Temperature Alerts During AF Ablation (PiLOT-AF Study)

Atrial fibrillation (AF) is a very common abnormal heart rhythm, triggered by rapid electrical activity originating from the pulmonary veins (PVs) that drain blood from the lungs back to the left atrium (LA). Ablation of the junction between the PVs and the LA, electrically isolating the veins from the heart, is the key to prevent AF.

When using radiofrequency energy (RF), transmural lesions are required to achieve permanent pulmonary vein isolation (PVI). New technologies are currently available to predict the ablation lesion depth and to guide the duration of each application. However, deeper lesions mean a higher risk of overheating and damage of adjacent structures such as the esophagus that lies against the back wall of the LA. In order to minimize this risk, the investigators continuously monitor the temperature inside the esophagus during the procedure through a probe placed in the esophagus and they promptly terminate energy delivery in case of any esophageal temperature rises more than 39°C.

To date, it is not known if a low power for a longer time is better than a high power for a shorter time when ablating on the LA posterior wall in order to create permanent scars without heating the esophagus.

Therefore, the investigators plan to compare the incidence of esophageal temperature alerts and the success of the procedure with four different energy settings during ablation on the LA posterior wall.

The PiLOT-AF study is a prospective single-centre randomized observational study aiming at comparing different radiofrequency energy (RF) settings during atrial fibrillation (AF) ablation on the left atrial (LA) posterior wall, in terms of esophageal heating, acute and long-term procedure success and procedural complications.

Patients scheduled for their first RF ablation, because of a history of symptomatic and drug-refractory paroxysmal or persistent AF, will be considered for inclusion in the study.

Potential subjects will initially be approached 4-6 weeks before their ablation procedure, in order to give them enough time to consider the information, to ask questions to the investigators, their family doctor or other independent parties to decide whether they wish to participate in the study or not.

For those interested in participation, a baseline assessment will be arranged to coincide with their standard pre-admission visit, for informed consent, screening and eligibility assessment and randomization.

All AF ablation procedures will be performed in a standard fashion, under general anaesthesia and with continuous esophageal temperature monitoring using a sinusoidal multi-sensor esophageal temperature probe (CIRCAtemp). After LA geometry reconstruction using 3-dimensional electroanatomical mapping EnSite Velocity and a multipolar circular mapping catheter St Jude Medical Optima, the ablation catheter Endosense Tacticath through a deflectable sheath St Medical Agilis will be used for Pulmonary Vein Isolation (PVI). Standardized RF settings will be used during ablation on the LA anterior wall as current practice in our centre. Different RF settings will be used on the LA posterior wall, according to randomization group. Moreover target values will be chosen for Lesion Size Index (LSI), a parameter useful to predict the lesion depth, during ablation on LA posterior wall. The duration of RF delivery on the LA posterior wall will be dictated by achievement of the target LSI or esophageal temperature rise \> 39◦C during ablation. PVI will be achieved and confirmed after 30 minutes waiting time. In case of acute PV reconnection, ablation at sites of breakthrough signals will be performed in order to achieve durable PVI. The occurrence of acute PV reconnection (PVR) with sites of breakthrough signals on the LA posterior wall will be recorded for each procedure. The total procedure and RF ablation times will be also collected.

After the ablation, before discharge the symptoms status and heart rhythm will be assessed and the patient will be instructed to commence a symptoms diary. Telephone follow-ups will be then performed at 3 and 6 months to assess current symptom status. Standard care follow-up Arrhythmia Clinic visits will be also performed 3-4 months after the ablation procedure. Ad hoc visits and/or additional investigations as prolonged electrocardiogram (ECG) monitoring will also take place, dictated by arrhythmia symptoms and assessment for potential adverse events related to the procedure, in accordance with standard practice.

The end of the study for each patient will be the date of the 6 months telephone follow-up.

Eligibility Criteria:
Inclusion Criteria:

* male or female, aged 18 to 80 years;
* willing and able to give informed consent for participation in the study;
* history of symptomatic and drug-refractory atrial fibrillation;
* planned atrial fibrillation (AF) ablation on a clinical basis.

Exclusion Criteria:

* previous AF ablation;
* pregnancy, trying for a baby or breast feeding;
* oesophageal obstruction (mass, stricture), diverticulum or varices, tracheo-oesophageal fistula or any other oesophageal conditions prohibiting the use of oesophageal temperature probe for continuous luminal temperature monitoring;
* any other significant disease or disorder which, in the opinion of the investigator, may either put the participants at risk because of participation in the study, or may influence the result of the study, or the participant's ability to participate in the study.