The purpose of this research project is to investigate if the long-term efficacy outcome
(freedom from arrythmia) when using an esophageal cooling probe is potentially better
than a standard of care temperature monitoring probe. This is the multi-center study is
being done to confirm single center study results showing better long term efficacy. This
study will also add to existing data showing reductions in esophageal injury with
optional EGDs.
At present, the method of protection is limited; an esophageal temperature monitoring
probe is inserted whilst the patient is under general anesthesia and the temperature is
measured during ablation, stopping if temperatures markedly increase, which may suggest
significant esophageal thermal injury. This method is unreliable as the temperature probe
does not sit well in the esophagus and is often too far away from the area requiring
monitoring. The probe is difficult to place as it can coil.
The esophageal cooling device (ensoETM) is another protection method that is gaining
popularity since receiving marketing authorization from FDA to reduce the likelihood of
ablation-related esophageal injury resulting from radiofrequency cardiac ablation
procedures. While the acute safety data has been accepted, long-term efficacy outcomes
improvements with use of ensoETM has not been confirmed outside of single center
randomized studies.
The design of the project is in the form of a randomized controlled trial like the
single-center studies, so participants will have a 50:50 chance of being allocated to the
study group receiving the esophageal cooling probe (ensoETM) or to the control group,
receiving the esophageal temperature monitoring probe.
The patient is blinded to the result of the randomization, to avoid bias/placebo effect.
If enrolled to the study group, the esophageal cooling probe (ensoETM) will be used. This
is a smooth medical-grade silicone multi-lumen esophageal probe (the device has a CE mark
and FDA clearance and is designed for the purpose of esophageal insertion and temperature
management) that allows water irrigation in a closed loop system, when connected to an
external console. If the console cools the irrigated water (this is controlled by manual
up/down buttons depending on what temperature is desired), the esophageal probe is then
cooled also, which allows local esophageal wall temperature to be controlled. Esophageal
cooling via the ensoETM probe can then counteract any transmitted thermal energy from the
ablation. The ensoETM has already received marketing authorization from FDA to reduce the
likelihood of ablation-related esophageal injury resulting from radiofrequency cardiac
ablation procedures.
The ablation procedure is normally done under general anesthetic so the participant will
not be aware of what group they are assigned and will not be subjected to any sensation
of pain or discomfort. The ensoETM probes are soft and much gentler than the camera probe
that the team normally have to insert during the catheter ablation procedure (the camera
probe or transesophageal echocardiography, TEE- is part of standard care), so the study
authors are of the opinion that this additional precautionary measure does not itself
increase the patient's risk or exposure to harm.
After the procedure, participants (study or control) may have an optional endoscopy
camera between 12-72 hours after the catheter ablation procedure to review for degree of
esophageal thermal damage caused by ablation, if any. The endoscopist is also blinded to
the result of the randomization to avoid bias during reporting of the endoscopy result.
The short time window between ablation and endoscopy camera follow up means that it can
be done at the same admission as the ablation procedure itself, this is advantageous for
the patient as both the ablation treatment and the follow up camera can be completed in 1
hospital admission. The endoscopy camera result is explained to the patient on the day
and if any further action required.
After this, normal/standard care clinic follow up of the patient will be adhered to but
as part of the trial, at the first clinic follow up, participants in both groups will be
asked about any lingering gastro-esophageal symptoms and a record is made of this, for
the study. The patient is still blinded to the results of the randomization at the time
of reporting their symptoms during recovery, if any. This is to avoid bias/placebo
effect.
The research project does not create any areas of ethical concern as the soft esophageal
cooling device/probe is of gentle design, specifically made to sit in the esophagus.
Especially when compared to the TOE probe that is normally used as part of standard
protocol for an AF ablation procedure. The patient will also not be aware of this step at
all as the procedure is conducted under general anesthesia. The device is appropriately
CE marked and FDA cleared for the indication of body cooling via the esophagus and with
marketing authorization to reduce the likelihood of ablation-related esophageal injury
resulting from radiofrequency cardiac ablation procedures. Even in standard care, an
esophageal temperature monitoring probe is required, so effectively, this study simply
randomizes the patient to either the esophageal cooling probe or another standard of care
probe, during their AF ablation.
There is one additional optional follow up the participant may have, as part of this
trial: the endoscopy camera (regardless of if randomized to study or control group). The
endoscopy camera will be completed by 12-72hrs post catheter ablation procedure. The
purpose is to review any areas of inflammation or thermal injury in the esophagus that
may alter clinical management but this specific information will also be used during
study analysis of the 2 randomized groups after the study has completed. An endoscopy
camera is considered to be a low risk outpatient procedure that takes 20 minutes to
complete. The risk of this camera test causing any damage itself is <0.5%. A TEE
probe/any other esophageal probe used during the ablation procedure is similar to the
endoscopy probe so apart from the participant attending an additional optional
appointment after their ablation, the overall risk to the patient is not significantly
increased.
The follow up endoscopy camera may be slightly uncomfortable in the beginning but it is
not painful, is straightforward and relatively quick- this will be explained in the
beginning during the recruitment process so the potential participant has an accurate
idea of what to expect from the endoscopy camera if they choose to get this procedure.
There is added benefit to the patient from this follow up, as the endoscopy camera will
confirm to the patient about any esophageal injury from ablation and if any treatment is
required. If no injury, this can help to reassure the patient before they go home.
Lastly, the follow up clinics will be as normal for the participant, only that
investigators will ask specifically for any ongoing gastroesophageal symptoms as well. A
record of this will be made.
The study authors reviewed the steps involved with this study design and concluded that
no major ethical or legal issue has been identified. The summary of the steps involved
here hopefully clarifies our viewpoint. From a management perspective, the centers
involved are able to conduct catheter ablation procedures for AF with general anesthetic.
The authors have experience and acquired the necessary equipment from the esophageal
cooling device company and have appropriate device management protocols and storage space
in place. The endoscopy department at the participating centers are also equipped to
support additional follow up with endoscopy tests post ablation.
Lastly, the proposed research trial has been similarly conducted in single-site settings
to great success and with excellent safety record with no probe-related trauma and the
team did not encounter any new or unexpected issues or difficulties. The authors obtained
good patient feedback from the single-center studies. This same trial will run at 5 or
more sites across the US with potential to further expand depending on statistical
analysis.