Abstract
Background
Catheter ablation (CA) has become the leading treatment option for patients with atrial fibrillation (AF). However, the use of thermal energy is still associated with the risk of specific complications, including atrio-oesophageal fistula (AEF). Several methods have been described to reduce the risk of AEF, such as adjusting the energy of a single application to limit oesophageal temperature (OT). Some authors have indicated the need for routine oesophageal monitoring if peri-procedural OT increased. Given the still limited knowledge on this topic, we assessed the frequency and nature of oesophageal lesions, including those of an ulcerative nature, in patients in whom a peri-procedural OT increase to above 41 ℃ was detected. We also searched for factors correlated with the risk of deep oesophageal injury, which are associated with a higher risk of AEF. The extent of oesophageal damage was analysed according to the Kansas City Classification depending on the type of anaesthesia.
Methods
We retrospectively analysed single-centre data of patients who underwent a radiofrequency (RF) ablation of AF using a “point-by-point” approach between 2013 and 2023. If the OT rose to above 41 ℃, we routinely screened the patients in-hospital for endoscopic abnormalities in the oesophagus. We analysed baseline patient characteristics, anatomical parameters, peri-procedural data, including the type of anaesthesia used, and post-procedural endoscopic findings in the oesophagus.
Results
The final analysis included 121 patients, mainly male subjects with paroxysmal AF primarily affected by hypertension. Most patients had preserved left ventricular systolic function and a slightly enlarged left atrium (LA). A “C”-type course of the oesophagus in relation to LA was predominant. Most patients underwent ablation under general anaesthesia (GA). The median of maximum OT recorded during application was 41.5 ℃. On endoscopy, features of thermal damage to the oesophagus were found in most patients-predominant erythema and mucosal oedema (60%). Superficial or deep ulcerations was found in 16 patients. In the multivariate analysis, higher body weight decreased the risk of injury, while deep sedation significantly increased the risk.
Conclusions
In a single-centre experience, an increase in OT above 41 ℃ during AF ablation using RF energy is associated with a high risk of oesophageal thermal injury of varying severity. Additionally, periprocedural deep sedation may further increase the extent of such injury.
Keywords: Radiofrequency ablation (RF ablation), atrial fibrillation (AF), oesophageal injury, sedation type, temperature probe
Highlight box.
Key findings
• An increase in oesophageal temperature (OT) above 41 ℃ during atrial fibrillation (AF) ablation using radiofrequency (RF) energy is associated with a high risk of oesophageal thermal injury of varying severity. Additionally, periprocedural deep sedation may further increase the extent of such injury.
What is known and what is new?
• The oesophageal thermal injury of varying severity is found in 20–50% of patients in the early period after thermal ablation. Several ways have been described to reduce the risk of the above complications. They include adaptation of the application energy to the adopted temperature limit on the probe placed in the oesophagus. The exceeding of 41 ℃ may leads to a higher incidence of local ulcer-like lesions. Unfortunately, implementation of the above preventive method did not completely protect patients undergoing RF ablation from the risk of thermal injury.
• Our analysis showed a high prevalence of the event if the temperature in the oesophagus rose above 41 ℃ during RF application. Only one in four patients remained free of iatrogenic lesions found in the in-hospital period. In 13% of patients, the lesions were ulcerated. Higher body weight was a factor preventing the occurrence of a large oesophageal lesion. In contrast, the use of deep sedation was associated with a six-fold increase in the risk of this event.
What is the implication, and what should change now?
• The avoiding of OT increase above 41 ℃ during RF application may reduce the incidence of oesophageal thermal injury after AF ablation. Furthermore, perioperative general anesthesia may be beneficial in limiting the extent of such injury. However, further studies are needed to confirm this observation.
Introduction
Catheter ablation (CA) has become the leading treatment option for patients with atrial fibrillation (AF) (1). The predominant sources of ablative energy are cryocatheters or electrodes emitting radiofrequency (RF) energy. Increasingly, electrodes used for performing pulsed field ablation (PFA) have also found practical applications. Unfortunately, each method is associated with the risk of specific and non-specific complications (2,3). Atrio-oesophageal fistula (AEF) is one of such complications primarily related to thermal methods (4). The risk of occurrence is difficult to assess and seems to be low (0.02–0.05%) and is associated with a high mortality rate (>70–80%) (5). Iatrogenic oesophageal changes in the early period after thermal ablation are found in 20–50% of patients (6,7). Oedema and slight swelling are predominant, while ulceration and active bleeding are rarely reported. Some of them, especially ulceration (8), evolve to AEF. The exact pathophysiology of this phenomenon is not fully understood.
Several ways have been described to reduce the risk of the above complications. They include lowering the ablative energy during application on the posterior wall of the left atrium (LA), modification of the application line around the pulmonary veins (PVs) to avoid proximity to the oesophagus, or using cooling intra-oesophageal balloons (6,9). It also seems that adaptation of the application energy to the adopted temperature limit on the probe placed in the oesophagus may be important (7). Based on the findings reported by Halm et al., a randomised trial dedicated to the analysis of the benefits of continuous oesophageal temperature (OT) measurement during ablation was performed. The authors concluded that continuous measurement of OT could reduce the risk of iatrogenic oesophageal damage. Furthermore, localised oesophageal ulcer-like lesions may be observed in patients whose intraluminal temperature reaches or exceeds 41 ℃ (10,11). However, the implementation of the above preventive methods did not completely protect patients undergoing RF ablation from the risk of AEF (12).
Given the still limited knowledge on this topic, we assessed the frequency and nature of oesophageal lesions, including those of an ulcerative nature, in patients in whom a peri-procedural OT increase to above 41 ℃ was detected. We also searched for factors correlated with the risk of deep oesophageal injury, which are associated with a higher risk of AEF (1,13). The extent of oesophageal damage was analysed according to the Kansas City Classification depending on the type of anaesthesia. We present this article in accordance with the STROBE reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-aw-2210/rc).
Methods
Study population
We retrospectively analysed single-centre data of consecutive adult patients undergoing ablation for symptomatic, antiarrhythmic treatment-resistant AF between 2013 and 2023, all of whom underwent endocardial RF current ablation using a “point-by-point” approach. To achieve the aims of the study, we analysed in detail patients who underwent esophagoscopy due to a peri-procedural OT increase to above 41 ℃ (7,12).
The following patients were excluded from the analysis: those with contraindications to ablation, including subjects with a thrombus in the cardiac cavities, including the left atrial appendage (LAA) using transoesophageal echocardiography (TEE) prior to the procedure, those in whom ablation was performed using a different technique (e.g., single-shot devices) or a different source of ablative energy (cryoablation, PFA), and those in whom esophagoscopy was not performed. Before undergoing medical procedures, all patients provided written informed consent for invasive diagnostic procedures and treatment. The flowchart of patients included in the final analysis is shown in Figure 1.
Figure 1.
Flowchart of patients included in the final analysis. AF, atrial fibrillation; OT, oesophageal temperature; PFA, pulse field ablation; RF, radiofrequency; PVI, pulmonary vein isolation.
This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Bioethics Committee of the Medical University of Silesia (No. BNW/NWN/0052/KB1/57/25) and informed consent was taken from all the patients.
Pre-ablation procedure
On admission, all patients underwent clinical and laboratory examinations, transthoracic echocardiography, and TEE. In the absence of contraindications, antiarrhythmic drugs, including beta-blockers, propafenone, sotalol, and amiodarone, were continued during the hospital stay and at discharge. In-hospital anticoagulant treatment, including vitamin K antagonists (VKAs), such as warfarin, acenocoumarol, or direct oral anticoagulant drugs (DOACs), including dabigatran, rivaroxaban, or apixaban, was administered according to the guidelines. When patients presented with an elevated international normalized ratio (INR) upon admission, ablation was postponed until the next day(s).
Ablation procedure
The AF ablation using RF energy was performed according to the established protocol (11). Details of our ablation approach had been described previously (14). After obtaining written informed consent, the procedures were performed, and patients were under anaesthetic care during the whole procedure. The decision to choose the method of anaesthesia was left to the discretion of the attending anaesthetist. In the absence of clinical contraindications, including allergies, each patient was administered 1 g of paracetamol and 2.5 grams of metamizole (dipyrone) intravenously prior to femoral veins puncture. For deep sedation, analgesics, including midazolam with the boluses of fentanyl or one of its derivatives, were used as clinically required. Importantly, during deep sedation, the patient remained conscious and responsive to verbal commands. The airway was routinely left unprotected and passive oxygen therapy was administered using an oxygen tube or mask. Sevoflurane and/or propofol were used for general anaesthesia (GA) in combination with mechanical airway ventilation. The drug dosage was adjusted by the attending anaesthetist based on various factors, including the patient’s age, body weight, and the results of parameters determining kidney and liver function.
Two diagnostic electrodes, i.e., a non-steerable electrode to the right ventricular apex and a steerable electrode to the coronary sinus, were inserted through venous femoral vascular access using the Seldinger technique. Under fluoroscopy guidance, a single transseptal puncture was performed at the typical site (the fossa ovalis) using a steerable transseptal puncture system and a Brockenbrough needle. After the transseptal puncture, unfractionated heparin was titrated to achieve and maintain an activating clotting time between 300–350 seconds. During each procedure, a three-dimensional (3D) electroanatomical Carto 3 system (Biosense Webster, Diamond Bar, CA, USA), or NavX-Ensite (St. Paul, MN, USA) was used, depending on the operator’s preference. Based on the 3D system, ablation was performed using ablation catheters-IBI CoolFlex (St. Jude Medical, St. Paul, MN, USA) for the NavX-Ensite system and Thermocool Smarttouch (Biosense Webster) for the Carto 3 system. First, circular PVs isolation was performed, and the decision to perform additional applications was at the discretion of the operator (1).
Oesophageal location and monitoring
In our centre, a temperature probe is routinely used for OT monitoring during all AF ablation procedures. All probes used were equipped with sensors arranged in series, visible on fluoroscopy. Depending on availability, either the SensiTherm Multi oesophageal monitoring system (Sensitherm, St. Jude Medical), which is equipped with seven sensors, or the S-Cath OT probe (Circa, Scientific), equipped with twelve sensors, was utilised. The probe was swallowed by the patient prior to the initiation of deep sedation. In the case of GA, the temperature probe was positioned in the oesophagus through the working channel of the laryngeal mask before the ablation. Initially, the probe was placed at the level of LA under fluoroscopy guidance. Then its position was changed if RF applications needed to be performed at a level below or above the sensors’ position. During application to the posterior wall of the LA, the application energy was usually reduced by adjusting it so that the temperature measured in the oesophagus was not higher than 41 ℃ (7). If the temperature exceeded 41 ℃, depending on the operator, the application energy was reduced, and occasionally the application site was adjusted. The maximum temperature reached on one of the temperature meters during the ablation was used for the analysis.
We used a subdivision already reported in the literature to determine the relationship between the course of the oesophagus and the position of the LA (15). The location of the oesophagus behind the left pulmonary veins (LPVs) was defined as “A”, the location of the oesophagus along the LPV orifices as “B”, the location of the oesophagus between the ostia of the LPVs and the right pulmonary veins (RPVs) as “C”, the location along the orifices of the RPVs as “D” and when the oesophagus was located more distally behind the RPVs as “E”. In the case of an oblique course, the course of the oesophagus in the longer segment in relation to the LA determined the location.
In patients who presented with an increase in OT >41 ℃ during ablation (7), we routinely performed oesophagoscopy during hospitalisation within 1–3 days following ablation, using Olympus GIF Q160 or GIF H180. The extent of oesophageal injury was described according to the Kansas City Classification-oesophagus without lesions (grade 0), minor oesophageal injury (grade 1: erythema/oedema without mucosal damage) and major oesophageal injury (grade 2a: superficial ulceration involving only the mucosa; grade 2b: deeper ulceration involving the external muscles; grade 3a: oesophageal perforation without fistula to the LA; grade 3b: oesophageal perforation with fistula) (15). The group of patients with major oesophageal injury included those with grade 2a, 2b, 3a and 3b. Therapeutic management was determined by the recommendations of the consulting gastrologist.
Statistical analysis
We presented quantitative variables as mean ± standard deviation or median and interquartile range. We tested the significance of differences using the Welch’s two-sample t-test for the normal distribution. The Wilcoxon rank sum test was applied for the distribution of non-normal variables. We presented qualitative variables as percentages and assessed the significance of differences using the Fisher’s exact test. Logistic regression analysis was employed to identify factors associated with a risk of major oesophageal injury following CA in a univariable model. Multivariable analysis, which included variables with a P value <0.1 found on univariable analysis, was performed to identify independent predictors for major oesophageal injury. The diagnostic utility of each parameter was evaluated using the area under the curve (AUC), sensitivity, specificity, and accuracy [receiver operating characteristic (ROC) curve]. The OT threshold was specified using the Youden index. The Hosmer-Lemeshow goodness-of-fit test was calculated for all parameters. A p value <0.05 was considered statistically significant, and all analyses were performed with SAS software (version 9.4; SAS Institute, Inc., Cary, NC, USA) and R software version 4.4.3 (R Foundation for Statistical Computing, Vienna, Austria).
Results
Baseline data of the group
The final analysis included 121 patients, mainly male subjects with paroxysmal AF (mean age: 60 years) primarily affected by hypertension. Detailed data on the baseline characteristics of the group are given in Table 1.
Table 1. Patient characteristics.
| Characteristics | Total (n=121) | Deep sedation (n=11) | General anaesthesia (n=110) | P value† |
|---|---|---|---|---|
| Age, years | 63 [55, 68] | 64 [56, 70] | 62 [55, 67] | 0.70 |
| Sex, male | 76 (62.8) | 7 (63.6) | 69 (62.7) | >0.99 |
| Weight, kg | 88±15 | 93±13 | 88±15 | 0.20 |
| BMI, kg/m2 | 28.7 [25.5, 32.9] | 31.0 [27.2, 33.9] | 28.4 [25.2, 32.9] | 0.50 |
| Paroxysmal AF | 91 (75.2) | 8 (72.7) | 83 (75.5) | >0.99 |
| CHA2DS2-VASc score | 2.0 [1.0, 3.0] | 3.0 [1.0, 5.0] | 2.0 [1.0, 3.0] | 0.14 |
| HAS-BLED score | 1.0 [1.0, 2.0] | 1.0 [1.0, 2.0] | 1.0 [1.0, 2.0] | 0.60 |
| Previous AF ablation | 21 (17.4) | 4 (36.4) | 17 (15.5) | 0.10 |
| Hypertension | 84 (69.4) | 8 (72.7) | 76 (69.1) | >0.99 |
| Hyperlipidaemia | 88 (72.7) | 8 (72.7) | 80 (72.7) | >0.99 |
| Diabetes mellitus | 32 (26.4) | 4 (36.4) | 28 (25.5) | 0.50 |
| CAD | 38 (31.4) | 3 (27.3) | 35 (31.8) | >0.99 |
| Previous MI | 9 (7.4) | 0 (0.0) | 9 (8.2) | >0.99 |
| Heart failure | 22 (18.2) | 5 (45.5) | 17 (15.5) | 0.03 |
| Stroke/TIA | 4 (3.3) | 1 (9.1) | 3 (2.7) | 0.30 |
| Implanted device (PM/ICD) | 13 (10.7) | 1 (9.1) | 12 (10.9) | >0.99 |
| Symptoms of GERD | 6 (5.0) | 1 (9.1) | 5 (4.5) | 0.50 |
| LVEF, % | 55.0 [50.0, 55.0] | 52.0 [35.0, 55.0] | 55.0 [50.0, 57.0] | 0.14 |
| Left atrial diameter, mm | 42±5 | 43±4 | 42±5 | 0.50 |
| Left atrial area, mm2 | 22.0 [19.1, 26.0] | 23.0 [20.0, 28.5] | 22.0 [19.1, 26.0] | 0.50 |
Data are presented as median [Q1, Q3], n (%), or mean ± SD. †, Wilcoxon rank sum test, Fisher’s exact test or Welch two-sample t-test were used. AF, atrial fibrillation; BMI, body mass index; CAD, coronary artery disease; GERD, gastroesophageal reflux disease; ICD, implantable cardioverter-defibrillator; LVEF, left ventricular ejection fraction; MI, myocardial infarction; PM, pacemaker; SD, standard deviation; TIA, transient ischaemic attack.
Perioperative and in-hospital data
Most subjects were under GA. In 40% of patients, the oesophagus was located between the LPV and RPV ostia in the ‘C’ position. In one out of five patients, in addition to PV isolation, additional ablation lines were performed on the posterior wall of the LA. The mean maximum temperature recorded in the oesophagus during application was 41.5 ℃. On endoscopy, features of thermal damage to the oesophagus were found in most patients. The predominant features were erythema and mucosal oedema (60%). Deeper damage in the form of superficial or deep ulcerations was found in 16 patients (13%). In two patients diagnosed with deeper ulceration from the GA group, hospital stays were prolonged. During the postprocedural period, in-hospital, clinical upper gastrointestinal bleeding was observed. No progression of oesophageal injury was noted, either during repeat oesophagoscopy performed during the hospital stay or during a subsequent hospitalization within 4 weeks of the procedure. Detailed data on the perioperative parameters, in-hospital period and oesophagoscopy findings are given in Tables 2,3.
Table 2. Peri-procedural data.
| Variable | Total (n=121) | Deep sedation (n=11) | General anaesthesia (n=110) | P value† |
|---|---|---|---|---|
| Position of the oesophagus | 0.30 | |||
| “A” position | 7 (5.9) | 0 (0.0) | 7 (6.4) | |
| “B” position | 46 (39.0) | 4 (36.4) | 42 (38.2) | |
| “C” position | 49 (40.5) | 5 (45.4) | 44 (40.0) | |
| “D” position | 16 (13.6) | 1 (9.1) | 15 (13.6) | |
| “E” position | 3 (2.5) | 1 (9.1) | 2 (1.8) | |
| Total fluoroscopy dose, mGy | 481 [297, 873] | 521 [313, 876] | 465 [293, 839] | 0.46 |
| Total fluoroscopy time, min | 10 [6.1, 14.9] | 11.3 [7.3, 17.3] | 9.2 [5.1, 16.9] | 0.31 |
| Maximum RF energy on the posterior wall of the LA, Watt | 15 [15, 30] | 15 [15, 30] | 15 [15, 30] | 0.99 |
| Maximum oesophageal temperature during RF application, ℃ | 41.5 [41.2, 41.8] | 42.0 [41.4, 42.4] | 41.5 [41.2, 41.8] | 0.08 |
| RF application on the posterior wall of the LA | 27 (22.4) | 3 (27.3) | 25 (22.7) | 0.73 |
| Time from ablation to oesophagoscopy, day | 2.0 [1.0, 3.0] | 3.0 [1.0, 4.0] | 2.0 [1.0, 4.0] | 0.45 |
Data are presented as n (%) or median [Q1, Q3]. †, Wilcoxon rank sum test, Fisher’s exact test or Welch two-sample t-test were used. LA, left atrium; RF, radiofrequency.
Table 3. Endoscopic findings and gastrointestinal drugs at discharge.
| Variable | Total (n=121) | Deep sedation (n=11) | General anaesthesia (n=110) | P value† |
|---|---|---|---|---|
| Extent of oesophageal damage according to the Kansas City Classification | 0.08 | |||
| Grade 0: without pathological changes | 32 (26.4) | 1 (9.1) | 31 (28.2) | |
| Grade 1: erythema/oedema without mucosal damage | 73 (60.3) | 6 (54.5) | 67 (60.9) | |
| Grade 2a: superficial ulcers involving the mucous membrane | 11 (9.1) | 3 (27.3) | 8 (7.3) | |
| Grade 2b: deeper ulceration involving the external musculature | 5 (4.1) | 1 (9.1) | 4 (3.6) | |
| Major oesophageal injury (grades 2a/2b) | 16 (13.2) | 4 (36.4) | 12 (10.9) | 0.04 |
| Fortuitous endoscopic lesions | ||||
| GERD | 29 (24.0) | 2 (18.2) | 27 (24.5) | 0.26 |
| Chronic gastritis | 14 (11.6) | 4 (36.4) | 10 (9.1) | 0.11 |
| GERD + chronic gastritis | 2 (1.7) | 2 (18.2) | 0 (0.0) | 0.58 |
| Oesophageal polyp | 1 (0.8) | 0 (0.0) | 1 (0.9) | 0.84 |
| Gastrointestinal drugs at discharge | ||||
| Proton pump inhibitors | 87 (71.9) | 9 (81.8) | 78 (70.9) | 0.12 |
| Itopride | 31 (25.6) | 9 (81.8) | 22 (20.0) | 0.17 |
| Linseed | 26 (21.5) | 6 (54.5) | 20 (18.2) | 0.34 |
| Sucralfate | 12 (9.9) | 0 (0.0) | 12 (10.9) | <0.001 |
Data are presented as n (%). †, Wilcoxon rank sum test, Fisher’s exact test or Welch two-sample t-test were used. GERD, gastro-oesophageal reflux disease.
Predictors of major oesophageal injury
Among the parameters included in the univariate analysis, an association was identified between major oesophageal injury and age, weight, risk estimated by the CHA2DS2-VASc score and the HAS-BLED score, maximum OT during RF application and periprocedural deep sedation. Among the parameters included in the multivariate analysis, an association was found between major oesophageal injury and maximum temperature in the oesophagus during RF application and deep sedation. Importantly, higher body weight decreased the risk of injury, while deep sedation significantly increased the risk. The results of the analyses are summarised in Tables 4,5. The relationship between OT and the AUC was characterized by the AUC value of 0.635 (0.496–0.773), with a sensitivity of 0.688 (0.413–0.89) and a specificity of 0.621 (0.52–0.715) (Figure 2). Moreover, we performed Hosmer and Lemeshow goodness of fit (P=0.23) as well as omnibus test of fit based on residuals of the model (P=0.57) which indicates a reasonable fit to the data.
Table 4. Univariable logistic regression analysis identifying predictors for high-grade oesophageal injury after ablation of AF.
| Variables | Odds ratio (95% CI) | P value |
|---|---|---|
| Age | 1.059 (1.003–1.113) | 0.056 |
| Sex, male | 0.544 (0.186–1.592) | 0.26 |
| Weight | 0.962 (0.919–1.003) | 0.08 |
| BMI | 0.944 (0.818–1.074) | 0.40 |
| Paroxysmal AF | 0.987 (0.312–3.769) | 0.98 |
| CHA2DS2-VASc score | 1.659 (1.195–2.376) | 0.003 |
| HAS-BLED score | 2.640 (1.347–5.631) | 0.007 |
| Previous AF ablation | 1.725 (0.442–5.658) | 0.39 |
| Hypertension | 3.500 (0.910–23.08) | 0.11 |
| Hyperlipidaemia | 1.733 (0.514–7.948) | 0.42 |
| Diabetes mellitus | 1.823 (0.573–5.414) | 0.29 |
| CAD | 0.992 (0.293–2.966) | 0.99 |
| Heart failure | 2.353 (0.672–7.406) | 0.15 |
| Stroke/TIA | 2.267 (0.108–19.06) | 0.49 |
| Implanted device (PM/ICD) | 1.221 (0.177–5.195) | 0.81 |
| LVEF | 1.004 (0.949–1.075) | 0.90 |
| Left atrial diameter | 1.078 (0.970–1.203) | 0.17 |
| Left atrial area | 1.000 (0.881–1.096) | >0.99 |
| Maximum oesophageal temperature during RF application | 2.095 (1.072–4.688) | 0.046 |
| RF application on the posterior wall of the LA | 2.264 (0.705–6.807) | 0.15 |
| Periprocedural deep sedation | 4.667 (1.094–17.99) | 0.03 |
AF, atrial fibrillation; BMI, body mass index; CAD, coronary artery disease; CI, confidence interval; ICD, implantable cardioverter-defibrillator; LA, left atrium; LVEF, left ventricular ejection fraction; PM, pacemaker; RF, radiofrequency; TIA, transient ischaemic attack.
Table 5. Multivariable logistic regression analysis identifying predictors for high-grade oesophageal injury after ablation of AF.
| Variables | Odds ratio (95% CI) | P value |
|---|---|---|
| Patient weight | 0.951 (0.907–0.997) | 0.04 |
| Maximum temperature in the oesophagus during RF application | 2.066 (0.964–4.432) | 0.06 |
| Periprocedural deep sedation | 6.406 (1.321–31.06) | 0.02 |
AF, atrial fibrillation; CI, confidence interval; RF, radiofrequency.
Figure 2.
The ROC curve for the oesophageal temperature as a predictor of elevated risk of major oesophageal injury during RF ablation, AUC 0.635 (0.496–0.773), sensitivity 0.688 (0.413–0.89), specificity 0.621 (0.52–0.715). AUC, area under the curve; FPR, false positive rate; RF, radiofrequency; ROC, receiver operating characteristic; TPR, true positive rate.
Analysis of patients according to the type of anaesthesia
Heart failure was statistically more frequently diagnosed in the group of patients undergoing ablation under deep sedation (P=0.03). In addition, no significant differences were observed in terms of baseline characteristics, including echocardiographic parameters. No significant differences were noted regarding maximum OT during RF application, total fluoroscopy exposure time, and other peri-procedural data, including the position of the oesophagus. The distribution of oesophageal injures according to the Kansas City Classification did not reach statistical significance (P=0.08). However, major oesophageal injury, which consisted of superficial ulcers involving the mucous membrane (grade 2a) and deeper ulceration involving the external musculature (grade 2b), occurred more frequently in the group of patients undergoing ablation under deep sedation (P=0.04). No significant differences were reported in incidental endoscopic oesophageal findings or gastrointestinal drugs at discharge according to the type of anaesthesia.
Discussion
Our analysis showed a high prevalence of the event if the temperature in the oesophagus rose above 41 ℃ during RF application. Only one in four patients remained free of iatrogenic lesions found in the in-hospital period. In 13% of patients, the lesions were ulcerated. Higher body weight was a factor preventing the occurrence of a large oesophageal lesion. In contrast, the use of deep sedation was associated with a six-fold increase in the risk of this event.
Continuous measurement of OT at the site of application is one of the methods that may identify patients at higher risk of AEF. Therefore, limiting the temperature in the oesophagus during application may significantly reduce the risk of oesophageal damage (16). The issue is the determination of the cut-off temperature value for which diagnostic control tests of the oesophagus are performed. Some authors have indicated the need for gastrointestinal surveillance in patients with OT exceeding 40 ℃, while others recommend close monitoring starting at 42 ℃ (17). In our study, the cut-off was set at 41 ℃, which is in line with the findings of Halm et al. (7). Based on this, we observed a high percentage of patients with iatrogenic changes in our cohort. A similar challenge arises with the established cut-off value for OT, beyond which the risk of AEF remains highly probable. The optimal cut-off point identified through ROC analysis was 41.7 ℃. However, it should be taken into account that the AUC value of 0.635, with a sensitivity of 0.688 and a specificity of 0.621, does not allow for definitive conclusions.
In addition to OT, many other parameters have been described in the literature as potential risk factors for oesophageal damage. Most of them being anatomical or procedure-dependent [e.g., lower body mass index (BMI), a poorer mediastinal fat layer (18), lower left ejection fraction (5), localisation of the oesophagus in relation to the LA (19), or smaller distance of the oesophagus from the posterior wall of the LA (6)]. However, periprocedural data are also important, with the use of the remote robotic navigation system (20), higher energy applications (20) and longer application times (15) on the posterior wall of LA. This group includes the method of periprocedural anaesthesia. In our observation, conducting the procedure under deep sedation was associated with increase in the risk of significant oesophageal injury. The predominant cause may be related to impaired oesophageal motility due to high dosages of fentanyl and midazolam administered during a single procedure. In addition, apart from the reduction of muscle tone, swallowing reflexes are not present, and nociceptive responses are suppressed or absent (18), which may lead to prolonged exposure to RF energy. This fact can also be confirmed by a less frequent occurrence of lesions following the use of a device to mechanically move the oesophagus away from the application site in the LA (21).
As already mentioned, AEF is rare but is a highly fatal complication. Therefore, the rate of patients developing haemorrhagic oesophageal lesions during hospitalization is of paramount importance. In our relatively limited cohort, two patients experienced this condition. In addition to the standard postoperative protocol, these patients underwent follow-up esophagoscopy during their hospitalization. Rigorous gastroenterological treatment was administered and follow-up esophagoscopy was repeated 3–4 weeks after the procedure during the hospitalization. In both cases, regression of the lesions and healing of the oesophagus were observed.
Unfortunately, the extended recruitment period complicates the drawing of more definitive conclusions from the current analysis. Significant advances in ablation technology were introduced between 2013 and 2023, including innovations in both ablation catheters and electrophysiological systems (such as the implementation of contact force or ablation index). Postprocedural esophagoscopy was not performed in all cases, most often due to the patient’s lack of consent to undergo the examination. Unfortunately, exact data regarding this are not available. Furthermore, we now have greater access to single-shot ablation systems, which has led to an increase in the number of procedures and shorter procedure durations. Despite this trend, the number of RF ablation procedures at our centre remains stable, with GA still being preferred by both patients and operators. The extensive availability of an anaesthesia team at our centre where these procedures were performed is also a key factor.
Limitations
This analysis is subject to several limitations, mainly related to its retrospective, single-centre design. We included a selected group of patients in whom elevated OT above 41 ℃ was reported during ablation. Only selected clinical, echocardiographic and peri-procedural parameters were analysed. There is no information on the detailed general anaesthetic protocol, which varied according to the experience of the anaesthetist. Two types of ablation electrodes were used, depending on the 3D system. Patients underwent esophagoscopy during hospitalisation (mainly on days 1–3 of hospital stay). We have limited data on the dynamics of oesophagoscopy image. The division into small and large oesophageal lesions was based on one classification (i.e., the Kansas City Classification). Given the limited number of events, it would be appropriate to acknowledge the risk of overfitting as a limitation.
Conclusions
In a single-centre experience, an increase in OT exceeding 41 ℃ during AF ablation using RF energy is associated with a high risk of oesophageal thermal injury of varying severity. Periprocedural deep sedation may further increase the extent of such injury.
Supplementary
The article’s supplementary files as
Acknowledgments
None.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Bioethics Committee of the Medical University of Silesia (No. BNW/NWN/0052/KB1/57/25) and informed consent was taken from all the patients.
Footnotes
Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-aw-2210/rc
Funding: This work was supported by an internal grant from the Medical University of Silesia in Katowice (grant No. BNW-NWD-610-23/60/2025).
Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-aw-2210/coif). Krzysztof Myrda reports that this work was supported by an internal grant from the Medical University of Silesia in Katowice (grant No. BNW-NWD-610-23/60/2025). The other authors have no conflicts of interest to declare.
Data Sharing Statement
Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-aw-2210/dss
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