Association between proactive esophageal cooling and increased lab throughput

Proactive esophageal cooling has been FDA cleared to reduce the likelihood of ablation‐related esophageal injury resulting from radiofrequency (RF) cardiac ablation procedures. Data suggest that procedure times for RF pulmonary vein isolation (PVI) also decrease when proactive esophageal cooling is employed instead of luminal esophageal temperature (LET) monitoring. Reduced procedure times may allow increased electrophysiology (EP) lab throughput. We aimed to quantify the change in EP lab throughput of PVI cases after the introduction of proactive esophageal cooling.


| INTRODUCTION
4][5] As a result, waiting lists for PVI procedures have lengthened. 6,7Tools or techniques that increase electrophysiology (EP) lab throughput may help alleviate this constraint.
A dedicated device for proactive esophageal cooling has recently received clearance from the US Food and Drug Administration (FDA) to reduce the likelihood of ablation-related esophageal injury resulting from radiofrequency (RF) cardiac ablation procedures. 8th increasing adoption of this safety device, additional findings have been reported with its use.0][11][12][13][14][15][16] Shorter procedures may help improve patient safety by minimizing the additional risk that comes with prolonged time under anesthesia 17 and may also allow more procedures to be completed. 18though proactive esophageal cooling reduces procedure duration, its potential influence on EP lab throughput has not been examined.This study aimed to quantify the change in EP lab throughput of PVI cases following the introduction of proactive esophageal cooling using a dedicated esophageal cooling device across three different EP groups.

| Study design and setting
This was a substudy of a larger retrospective review of prospectively collected data (Advarra IRB #Pro00066277).All patients undergoing left atrial ablation for the treatment of AF with PVI over the specified time frame were included in the study.Data from three EP labs in hospital systems were collected over equal time frames before (preadoption) and after the adoption (post-adoption) of cooling.In the pre-adoption time frame, LET monitoring (with esophageal deviation when selected by the operator) was used as a means of esophageal protection.In the post-adoption time frame, proactive esophageal cooling (ensoETM ® ; Attune Medical) was adopted in September

| Data analysis
The total number of procedures completed in each equivalent time frame were compared to determine the difference between procedure volumes accomplished with proactive cooling and without it.
Statistical significance of the increase in rate was assessed assuming that the number of procedures before and after cooling followed the Poisson distribution with equal rate parameters; we used the twosided level 0.05 exact test implemented via the poisson.testfunction in R.This function also provided a 95% confidence interval (CI) for the rate ratio.

| RESULTS
In total, 2498 patients underwent PVI ablations over a combined 74 months across three sites.No operators were added during the months after adoption, and no new lab space was opened, but two sites lost one operator each during their post-adoption phase.At each respective site, there was a nearly equal number of operating days in the pre-adoption and post-adoption periods (Table 1).

| Esophageal protective measures
In the pre-adoption cohort, single sensor (various manufacturer's) or multisensor LET monitoring (CIRCA Scientific; S-cath) was utilized for all patients.In all three sites, esophageal deviation (EsoSure Esophageal Retractor) was also utilized in select cases.In the procedures that underwent multisensor LET monitoring, the probe was placed under fluoroscopic guidance and was subsequently used to monitor the temperature of the esophagus throughout the procedure.When the esophagus reached a temperature of 39°C, RF was immediately discontinued and the area was allowed to cool to the initial baseline temperature of that location as recorded on the LET monitor, or to a temperature of 36.5°C.In cases using single sensor probes, the temperature probe was repositioned as needed during the ablation to optimally position the temperature sensor opposite the RF catheter.
While awaiting return to equilibrium or baseline temperature, energy was typically applied to another region of the atrium.
In the post-adoption phase, procedures utilized proactive cooling (ensoETM ® ; Attune Medical) as a means of esophageal protection instead of LET monitoring or esophageal deviation.The ensoETM is a single-use device that consists of a closed system silicone tube that is placed into the esophagus before the delivery of RF energy.Distilled water circulates through the device at a rate of 2.4 L/min and a temperature-controlled heat exchanger keeps the water at a temperature of 4°C throughout the procedure, which in turn cools the esophagus.The device has been increasingly adopted for use as a means of esophageal protection, with over 60 000 cases completed to date. 11,12,14,15In September, 2023, the device received marketing authorization from the FDA to reduce the likelihood of ablationrelated esophageal injury resulting from RF cardiac ablation procedures.Due to the nature of the device, there is no temperature sensor, and thus, no need for the interruption of RF delivery due to local overheating or temperature alarms.Placement of the device is analogous to that of the standard orogastric tube which it replaces, and no repositioning is required once the device is confirmed to be in proper place by either fluoroscopy or intracardiac echocardiography.
Because of the insulating effect of the layers of the fibrous pericardium, serous fluid layer, and pericardial fat, no degradation in transmurality is seen on the intended lesions placed in the left atrium.

| DISCUSSION
Proactive esophageal cooling was recently cleared by the FDA to reduce the likelihood of ablation-related esophageal injury resulting from RF cardiac PVI ablation procedures, with a large multicenter review of over 25 000 patients showing significant reductions in atrioesophageal fistula formation associated with proactive esophageal cooling. 8,11In this first formal analysis of the changes in EP lab throughput associated with the adoption of proactive esophageal cooling, we found that the adoption of proactive esophageal cooling was associated with a 43.5% increase in EP lab throughput when compared to the throughput achieved with LET monitoring and esophageal deviation.Moreover, this increase occurred despite the loss of one operator each in two of the three sites analyzed.This increased lab throughput is attributed to the reduced procedural duration achieved with the use of proactive esophageal cooling.
T A B L E 2 Summary of results.
2021, November 2021, and March 2022 at each respective site in place of LET monitoring or deviation.The analysis period was divided into two separate time frames with equivalent duration: pre-adoption of proactive esophageal cooling, and post-adoption of proactive esophageal cooling.Despite the loss of two operators in the post-adoption phase of the study, this design enabled comparison of procedural volumes between the two time frames while keeping location and patient demographics consistent throughout the study.
Procedural methods and approaches used for left atrial PVI ablations in this site reflect those used by most hospitals performing atrial ablations in the United States.All patients in the study were put T A B L E 1 Number of operating days at each site before and after the adoption of proactive esophageal cooling.

Table 2 ,
with differences shown graphically in Figure1.Procedure time reductions across sites ranged from 10% to 40%.
Therefore, the switch to proactive esophageal cooling was associated with an overall 43% increase (rate ratio of 1.43, p < .0001) in EP lab throughput across the three hospitals, with a 95% CI of 1.32−1.56,despite the loss to different practices of one operator each in two of the three sites during the post-adoption period.Procedure time reductions across sites ranged from 10% to 40%.