Canadian Journal of Cardiology 30 (2014) 388e395
Review
Atrioesophageal Fistula in the Era of Atrial Fibrillation Ablation: A Review Girish M. Nair, MBBS, MSc, FRCPC,a Pablo B. Nery, MD,a Calum J. Redpath, MBBS, PhD, MRCP,a Buu-Khanh Lam, MD, CM, MPH, FRCSC,b and David H. Birnie, MB, ChB, MD, MRCPa a
Arrhythmia Service, Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada b
Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
ABSTRACT
RESUM E
The purpose of this review is to understand the epidemiology, clinical features, etiopathogenesis, and management of atrioesophageal fistula (AEF) after atrial fibrillation (AF) ablation. The incidence of AEF after AF ablation is 0.015%-0.04%. The principal clinical features include fever, dysphagia, upper gastrointestinal bleeding, sepsis, and embolic strokes. The close proximity of the esophagus to the posterior left atrial wall is responsible for esophageal injury during ablation. Prophylactic proton pump inhibitors, esophageal temperature monitoring, visualization of the esophagus during catheter ablation, esophageal protection devices, and avoidance of energy delivery in close proximity to the esophagus play an important role in preventing esophageal injury. Early surgical repair or esophageal stenting are the mainstay of treatment. Eliminating esophageal injury during AF ablation is of utmost importance in preventing AEF. A high index of suspicion and early intervention is necessary to prevent fatal outcomes.
pide miologie, les caLe but de cette revue est de comprendre l’e ristiques cliniques, l’e tiopathogenèse et la prise en charge de la racte fistule atrio-œsophagienne après l’ablation de la fibrillation auriculaire quence de la fistule atrio-œsophagienne après l’ablation de (FA). La fre ristiques clila FA est de 0,015 % à 0,04 %. Les principales caracte niques incluent la fièvre, la dysphagie, le saignement dans le tractus rieur, la sepsie et les accidents vasculaires gastro-intestinal supe re braux d’origine embolique. La proximite imme diate de l’œsophage ce rieure de l’oreillette gauche est responsable des et de la paroi poste sions œsophagiennes au cours de l’ablation. Les inhibiteurs de la le rature pompe à protons en prophylaxie, la surveillance de la tempe œsophagienne, la visualisation de l’œsophage au cours de l’ablation ter, les dispositifs de protection de l’œsophage et l’e vitement par cathe nergie à proximite imme diate de l’œsophage jouent un des sources d’e vention des le sions œsophagiennes. La rôle important dans la pre paration chirurgicale pre coce ou la pose d’une endoprothèse re limination des œsophagienne constituent le pilier du traitement. L’e sions œsophagiennes au cours de l’ablation de la FA est de la plus le vention de la fistule atriogrande importance dans la pre leve de suspicion et une intervention œsophagienne. Un indice e coce sont ne cessaires pour que l’issue ne soit pas fatale. pre
Atrial fibrillation (AF) is the most prevalent arrhythmia encountered in clinical practice. The prevalence of AF is 0.1% in those younger than 55 years and increases to approximately 9% in those older than 80 years. Catheter and surgical ablation procedures were introduced more than a decade ago for treatment of highly symptomatic individuals, usually younger than 75 years, with drug-refractory paroxysmal and persistent AF.
Increasing operator experience and advances in technology over the past decade have led to a dramatic rise in the number of ablation procedures worldwide.1,2 A worldwide survey on catheter ablation for AF from 182 centres in 24 countries reported 20,825 catheter ablation procedures on 16,309 AF patients between 2003 and 2006. The survey highlighted the feasibility, safety, and short- to medium-term effectiveness of catheter ablation for AF. However, the survey also listed a 4.5% risk of major complications associated with catheter ablation.3-5 The major complications associated with catheter ablation procedures for AF include cardiac tamponade, hemo- and/or pneumothorax, vascular access-related complications, stroke, pulmonary vein (PV) stenosis, atrioesophageal fistula (AEF), and death. Multiple case reports and series have described
Received for publication October 29, 2013. Accepted December 17, 2013. Corresponding author: Dr Girish M. Nair, H-1285 B, University of Ottawa Heart Institute, 40 Ruskin Ave, Ottawa, Ontario K1Y 4W7, Canada. Tel.: þ1-613-761- 4820. E-mail: [email protected] See page 394 for disclosure information.
0828-282X/$ - see front matter Ó 2014 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.cjca.2013.12.012
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AEF after catheter and surgical AF ablation. AEF has been reported after catheter ablation using radiofrequency (RF), cryoenergy, and high-frequency focused ultrasound energy.5-9 AEF is an uncommon yet invariably fatal complication of AF ablation. It results from injury to the esophagus during catheter ablation that occurs due to the close proximity of the esophagus to the posterior wall of the left atrium (LA), especially antral ablation sites.10-14 Surveys on catheter ablation for AF have reported a 0.015%-0.04% incidence of confirmed AEF after catheter AF ablation procedures. AEF is the second most common cause of mortality and accounts for 16% of cases of mortality after AF ablation. The reasons for high mortality associated with this complication is due to failure of early recognition as a result of lack of clinical awareness, delayed presentation, and complex surgical repair required for treatment.3-5,9,15,16 Although thoracic surgeons and gastroenterologists have long been aware of AEF as a complication after gastroesophageal surgery, cardiologists had never encountered this potentially lethal complication until the advent of catheter ablation for AF. This review addresses the rare, albeit potentially fatal, complication of AEF after AF ablation procedures and aims to provide the clinician with an overview of the clinical presentation, etiopathogenesis, and management of this condition. Clinical Case Examples The cases presented highlight the clinical presentations of AEF after catheter ablation for AF. Case 1 A 63-year-old man presented to the emergency department (ED) with history of high-grade fever associated with chills and rigours for 4 days. While being evaluated in the ED he had massive hematemesis leading to circulatory collapse and death. He had complained of retrosternal pain, aggravated while swallowing food, for a week before the presentation. Six weeks before the event he had undergone a catheter ablation for AF. Autopsy revealed an AEF (see Fig. 1), infective endocarditis, and abscesses in multiple internal organs.
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Case 2 A 62-year-old woman presented to the ED with confusion, weakness of the left half of the body, and high-grade fever with chills and rigours. Magnetic resonance imaging (MRI) of the brain revealed multiple septic emboli. The patient had catheter ablation for AF 4 weeks before presentation. Contrast enhanced computed tomography (CT) scan revealed evidence of AEF (see Fig. 2). Autologous pericardial patch repair of the AEF, from the endocardial surface of the LA, was performed under cardiopulmonary bypass (see Fig. 3). After this, an upper gastrointestinal (UGI) endoscopy was performed, which revealed esophageal ulceration (Fig. 4). Surgical repair of the esophageal aspect of the AEF was performed using a pleural flap. The patient needed intensive care along with broad-spectrum antibiotics for sepsis. This case demonstrates the need for early detection and treatment along with close cooperation between emergency physicians, cardiologists, radiologists, and cardiac and thoracic surgeons. Clinical Features and Diagnostic Investigations AEF typically presents between 2 and 6 weeks after catheter ablation. Common clinical features of AEF include dysphagia, nausea, heartburn, hematemesis or melena, high fever, sepsis, pericardial or pleural effusions, mediastinitis, seizures, and strokes.15,17,18 A high degree of clinical suspicion for esophageal injury and possible AEF should be entertained in patients presenting with the clinical features described and a recent history of AF ablation. Leukocytosis is one of the earliest and most sensitive laboratory markers in almost all patients with AEF.15 UGI endoscopy should be avoided in patients suspected to have AEF because massive cerebral air embolization has been reported after air insufflation during endoscopy.15 Thoracic CT scan is the investigation of choice in patients with suspected AEF and the radiological features include pericardial effusion, intravascular air, inflammation of atrial and esophageal tissue, frank communication between the atrium and the pericardium or the esophagus, and extensive systemic septic or food emboli.15-19
Figure 1. Autopsy specimen of the left atrium from a patient with atrioesophageal fistula after atrial fibrillation ablation. The location of the atrioesophageal fistula is at the ablation site in the posterosuperior aspect of the antrum of the left common pulmonary vein. Image courtesy of Jennifer Walsh, MD, FRCPC, Chief, Laboratory Medicine, Halton Healthcare Services, Oakville, ON, Canada.
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Figure 2. Computed tomography images (unenhanced and contrast-enhanced) showing air in the left atrium and pericardial cavity. In addition a clot, partially occluding the atrioesophageal fistula at the level of the left superior pulmonary vein, is seen in the left atrium.
Pathophysiology of AEF The close anatomic relationship of the esophagus and the LA is the most important factor responsible for the pathogenesis of esophageal mucosal injury during AF catheter ablation. The esophagus is situated in a groove posterior to the LA, bounded by the aorta on the left and the vertebral column
posteriorly. The esophagus follows a variable course and might be encountered adjacent to the left or right PVs or the mid portion of the posterior LA wall. In addition, the posterior LA wall, the fat pad, and connective tissue layer between the LA and the esophagus have variable thickness. Patients with LA dilatation have thinner fat pads and a larger contact area
Figure 3. Surgical photographs showing the site of the atrioesophageal fistula, autologous pericardial patch repair, and clots extracted from the left atrium that were partially occluding the fistula.
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Figure 4. Upper gastrointestinal endoscopy during surgical repair of an atrioesophageal fistula demonstrating esophageal mucosal injury.
between the esophagus and the LA. This region contains vascular structures, branches of the vagus nerve, and lymph nodes. Injury to these structures during AF catheter ablation is though to contribute to the genesis of AEF.20-23 The delayed presentation after AF ablation (2-6 weeks) makes it unlikely that mechanical perforation of the atrial wall during catheter ablation is a mechanism responsible for development of AEF. A canine model of esophageal injury and AEF after applications of ultrasound energy in the LA demonstrated that luminal esophageal temperature (LET) in excess of 50 C resulted in transmural esophageal necrosis with ulceration. High LET ( 50 C) resulting in esophageal ulceration occurred only when energy was applied in the LA within 2 mm of the esophagus.24 Thermal injury is thought to affect the microvasculature of esophageal tissue leading to ischemic necrosis of the mucosal layers. Damage to esophageal connective tissue and posterior LA wall has been noticed on endosonography after AF catheter ablation.25 The progression of esophageal ulceration to ultimate AEF formation was associated with gastric hypomotility, pyloric spasm, esophagitis, and lower esophageal sphincter relaxation, as a consequence of periesophageal vagal plexus injury and resultant acid reflux.25-28 UGI and capsule endoscopy have shown a 2%-20% incidence of esophageal injury in human subjects after catheter ablation for AF.10-12,19,29 Halm and colleagues found asymptomatic esophageal injury in 15% of subjects undergoing UGI endoscopy after catheter ablation for AF or left atrial tachycardia. The lesions varied in size from 2 to 16 mm. The authors found that subjects with intraluminal esophageal temperatures less than 41 C during catheter ablation did not show endoscopic evidence of esophageal injury. Subjects with esophageal signs of mucosal injury had greater LET (42.6 1.7 C vs 41.4 1.7 C). The odds of esophageal injury increased by a factor of 1.36 for every 1 C increase in LET.11 Di Biase and colleagues used capsule endoscopy after AF catheter ablation and detected a 17% incidence of mucosal esophageal injury.12 The same group also explored the relationship between esophageal injury and the type of anaesthesia used during AF catheter ablation. They found a 48% incidence of esophageal mucosal injury in patients undergoing AF catheter ablation under general anaesthesia compared with a 4% incidence in those receiving conscious sedation. In this study the LET in the general anaesthesia group was higher than the local
anaesthesia group (40.6 1 C vs 39.6 0.8 C). Reduced esophageal peristaltic movement and lack of swallowing along with use of a nasogastric tube leading to fixation of the esophagus were thought to be responsible for the increased incidence of esophageal injury in the general anaesthesia group.29 Martinek and colleagues found proximity of the esophagus to the LA posterior wall (3-5 mm) to be a marker for esophageal injury in human subjects. The esophagus is sandwiched between the LA anteriorly, and the thoracic vertebral column and aorta posteriorly; especially in patients with dilated LA. This is thought to contribute to esophageal compression and increased risk of esophageal injury. In addition extensive ablation in the posterior wall of the LA and higher RF energy (25 W compared with 15 W) were associated with increased incidence of esophageal injury. However, general anaesthesia was not associated with an increase in the risk of esophageal injury compared with conscious sedation in this study (2.7% vs 2.2%).10,14 The presence of gastroesophageal reflux associated with catheter ablation is thought to contribute to esophageal injury. Esophageal ulceration is thought to result in mediastinitis, erosion of the pericardium, and posterior LA wall AEF formation.24,26 Yamasaki and colleagues performed UGI endoscopy in 104 patients 48 hours after AF catheter ablation to detect esophageal injury. The subjects had undergone AF catheter ablation under conscious sedation with a maximum energy of 20-25 W, using irrigated tip catheters, for a maximum duration of 30 seconds on the posterior wall of the LA. Some subjects (9.6%) were found to have esophageal injury. All subjects with esophageal injury had body mass index < 24.9. The proposed explanation for this finding was that the posterior LA wall was closer to the esophagus in individuals with normal body mass index and that they had less connective tissue between the esophagus and the LA leading to a greater chance of mucosal thermal injury.30 Prevention of Esophageal Injury Imaging the esophagus before ablation Imaging the esophagus (CT/MRI scans) and visualizing its course in relation to ablation sites in the posterior wall of the
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LA or the coronary sinus plays an important role in prevention of esophageal injury (see Fig. 5). Kennedy and colleagues obtained cine-fluoroscopic images during swallowed barium contrast to record the course of the esophagus prior to repeat catheter ablation. The images were tagged on the 3D map during repeat ablation and the position of the esophagus, relative to the PVs, was found to be identical to its position during the initial procedure.31 Piorkowski and colleagues found excellent correlation between the location of the esophagus, determined on preprocedural CT scan, and its intraprocedure position determined using electroanatomic mapping systems.32 Three-dimensional rotational CT or MRI scans using swallowed barium or gadolinium contrast are also used to improve visualization of the esophagus. However, these methods display the esophageal location before or on the day of the procedure. The position of the esophagus is quite variable and might change by as much as 15 mm, limiting the usefulness of imaging in some situations.33-35 Threedimensional real-time images of the esophagus generated using electroanatomic mapping systems or intracardiac echocardiography can be used to avoid ablation in the LA within 3-5 mm of the esophagus. Real-time imaging has the advantage of detecting changes in esophageal position during the ablation procedure, allowing the operator to adjust ablation sites to avoid the esophagus.36-38 Esophageal mucosal protection Esophageal injury after atrial ablation lesions has been demonstrated in a canine model.24 UGI endoscopy after catheter ablation for AF has demonstrated a 2%-20% incidence of esophageal injury and mucosal ulceration.10,12,14,29 Esophageal mucosal injury has been shown to lead to progressive ulceration ultimately resulting in the development of AEF.39 Patients with esophageal injury are aggressively treated with proton pump inhibitors (PPIs) and undergo enhanced surveillance for features suggestive of AEF.10,12 Insights into the etiopathogenesis of AEF and the knowledge that esophageal injury is a precursor of AEF have prompted prophylactic PPI therapy for patients undergoing catheter ablation.
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However, the effectiveness of PPI therapy in preventing AEF in ablation patients is unlikely to be tested in prospective, randomized trials because of the very low incidence of this complication.26 Techniques to prevent esophageal injury during catheter ablation LET monitoring. A temperature probe in the esophagus, positioned as close as possible to the ablation catheter, can alert the ablator to increases in LET. This information can be used to titrate or interrupt energy delivery. Singh and colleagues performed a retrospective comparison of esophageal mucosal injury in patients undergoing AF catheter ablation with and without LET monitoring during AF catheter ablation. The group undergoing ablation with LET monitoring had ablation energy limited or interrupted when the temperature reached 38.5 C. There was a significantly lower incidence of esophageal injury in the monitored group compared with the unmonitored group (6% vs 36%).19 Sause and colleagues used a special triple-thermocouple LET monitor during AF catheter ablation to limit energy delivery to a luminal temperature of 40 C. Only 1.6% of subjects enrolled in the study developed esophageal mucosal injury.40 Perzanowski and colleagues performed LET monitoring using a deflectable catheter. The recording tip was positioned as close as possible to the site of ablation on the posterior LA wall. Ablation was limited to 25 W and was interrupted when the LET increased by 2 C. None of the subjects included in this study developed mucosal injury during follow-up. However, the LET might not be reliable if the temperature catheter is not close to the ablation site or if the esophagus is large. The esophageal temperature might continue to increase in most patients even after RF delivery is interrupted.41 LET might be significantly lower than esophageal mural temperature and esophageal mucosal injury might occur even after temperature monitoring, resulting in AEF.29,42,43 LET monitoring, though very effective in reducing esophageal mucosal injury, might not be sufficient to eliminate esophageal injury and AEF because of its limitations.
Figure 5. Three-dimensional computed tomography reconstruction demonstrating the close proximity of the esophagus to the posterior wall of the left atrium. In this case, the esophagus is located immediately behind the left pulmonary veins.
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Limiting energy delivery on the posterior LA wall. Limiting the energy delivered using open-irrigated ablation catheters to 25-30 W on the posterior LA wall has been shown to reduce esophageal mucosal injury.10,11,40 Rillig and colleagues found significant LET increase in most (76%) subjects undergoing AF catheter ablation using a robotic navigation system. After ablation, 14% of subjects were found to have esophageal mucosal injury on endoscopic examination after the procedure.44 Tilz and colleagues compared robotic navigation (RN)-assisted catheter ablation with manual catheter ablation in human subjects. Subjects underwent RN-assisted catheter ablation with a power setting of 30 W or 20 W, contact force between 10g and 40g, and open irrigation at 17 mL/m2. Ablation was terminated if LET reached 41 C. Almost all patients in the 30 W arm developed esophageal mucosal injury detected using endoscopic examination and 1 patient went on to develop esophageal perforation. Only 12% of patients in the manual ablation arm and 1 patient in the 20 W RN ablation arm developed esophageal mucosal injury. This study highlights the need for limiting energy delivery during ablation on the posterior LA wall.45 Force-sensing catheters and other tools to directly visualize the posterior wall of the LA during ablation might help to reduce the incidence of esophageal mucosal injury. Mechanical deflection of the esophagus during catheter ablation. The anatomical course of the esophagus behind the posterior wall of the LA and the coronary sinus puts it at risk for injury during catheter ablation.20,21 The distance between the posterior LA wall and the esophagus was found to be < 5 mm in 40% of autopsy specimens.20 Lemola and colleagues used CT scans to demonstrate that the fat pad intervening between the esophagus and the posterior LA wall is discontinuous in most subjects and is variable in its thickness (0.31.3 mm; 0.9 0.2 mm).46 Mechanical displacement of the esophagus to move it away from the site of LA posterior wall ablation has been used to limit mucosal injury. Chugh and colleagues used a deflectable UGI endoscope to deflect the esophagus away from the site of ablation. However, the endoscope had to be removed before energy delivery to avoid shunting of RF energy. After removal of the endoscope, the esophagus remained in the displaced position in very few subjects, making it unlikely that this technique was effective. Real-time imaging was not used in this study to ascertain if the esophagus was merely stretched using the endoscope or actually displaced away from the ablation site.47 Koruth and colleagues used an endotracheal stylet introduced into a thoracic chest tube to deflect the esophagus away from ablation sites in the LA. This technique allowed the esophagus to be moved 2.8 cm on average. LET monitoring was performed during ablation and showed that the esophageal temperature did not increase to > 40 C in any subject. One subject (5%) with an unusual atrial diverticulum overlying the posterior LA wall developed mucosal injury after ablation. Twelve (63%) patients showed signs of esophageal trauma related to instrumentation. However, none of these patients had any clinical sequelae.48 These case series seem to suggest that mechanical displacement of the esophagus during AF catheter ablation might limit mucosal injury. However, it will be very difficult to prove that this reduction in esophageal
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mucosal injury can reduce the incidence of AEF because of the low incidence of this complication. Esophageal insulation from thermal injury. Thermal insulation of the esophagus by inserting a removable barrier between the posterior LA wall and the esophagus is another strategy used to limit mucosal injury. Buch and colleagues positioned a fluid-filled balloon catheter, using a percutaneous pericardial approach, into the oblique sinus to move the esophagus away from the LA. This intervention allowed PV isolation without esophageal heating or injury in a patient in whom a previous PV isolation procedure had to be aborted because of esophageal luminal heating.49 Nakahara and colleagues evaluated this technique in a porcine model to demonstrate that an intrapericardial balloon, interposed between the esophagus and the LA, consistently allowed prevention of LET increase. The presence of the fluid-filled balloon in the pericardial space did not result in hemodynamic compromise.50 It might be difficult to use this technique routinely during AF ablation procedures because of the need for percutaneous pericardial access and the possibility of associated complications such as bleeding and infection. However, it can be used in select individuals in whom PV isolation cannot be achieved because of LET increase. Treatment of AEF A high index of suspicion should be exercised by treating physicians for early identification of patients with AEF. A wallet card listing the clinical features of AEF and the need for diagnostic imaging with CT scan might help alert patients and emergency physicians to recognize this condition early and intervene expeditiously (see Supplemental Fig. S1). Immediate surgery after onset of symptoms might help prevent fatalities and other serious outcomes such as air and food embolism. The surgical technique usually involves a combined cardiac and thoracic approach under cardiopulmonary bypass. The atrial aspect of the AEF is repaired using autologous pericardial patch and the esophageal aspect is repaired using a pleural or muscular flap.51-53 Adjunctive care with antibiotics and nutritional support in an intensive care setting is critical. An expectant management strategy including intravenous antibiotics has been shown to be associated with poor outcomes.15,16,18 Successful nonsurgical treatment in 3 cases of AEF with esophageal stenting and pericardiocentesis has been reported. The esophageal stents were removed after complete resolution of the AEF. Close communication with the gastroenterologist, and thoracic and cardiac surgeons is critical to successful management of patients with AEF.17,18 Summary AEF after AF ablation is an uncommon yet catastrophic complication almost always associated with a fatal outcome. Prevention of esophageal injury during ablation is of utmost importance. Strategies to identify the esophagus and avoidance of energy delivery in close proximity to the esophagus, esophageal protection devices, and esophageal temperature monitoring are the most important preventive strategies that should be considered during catheter ablation. Prophylactic proton pump inhibitor therapy for esophageal mucosal
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protection has been shown to be effective in preventing esophageal injury. Patient and physician education to recognize early symptoms and signs of AEF is important. Early definitive surgical intervention or nonsurgical esophageal stenting is recommended in patients with AEF. The possibility of fatal complications such as AEF, strokes, and death might be the reason that current guidelines recommend catheter ablation only for high burden, symptomatic AF patients refractory to antiarrhythmic medications. Acknowledgements The authors thank Dr Jennifer Walsh for providing autopsy photographs from a patient who developed AEF after catheter ablation for AF. Disclosures The authors have no conflicts of interest to disclose. References 1. Calkins H, Kuck KH, Cappato R, et al. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, end points, and research trial design: a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation. Developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology (ESC) and the European Cardiac Arrhythmia Society (ECAS); and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). Endorsed by the governing bodies of the American College of Cardiology Foundation, the American Heart Association, the European Cardiac Arrhythmia Society, the European Heart Rhythm Association, the Society of Thoracic Surgeons, the Asia Pacific Heart Rhythm Society, and the Heart Rhythm Society. Heart Rhythm 2012;9:632-696.e21.
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22. Maeda S, Iesaka Y, Uno K, et al. Complex anatomy surrounding the left atrial posterior wall: analysis with 3D computed tomography. Heart Vessels 2012;27:58-64. 23. Jang SW, Kwon BJ, Choi MS, et al. Computed tomographic analysis of the esophagus, left atrium, and pulmonary veins: implications for catheter ablation of atrial fibrillation. J Interv Card Electrophysiol 2011;32:1-6. 24. Yokoyama K, Nakagawa H, Seres KA, et al. Canine model of esophageal injury and atrial-esophageal fistula after applications of forward-firing high-intensity focused ultrasound and side-firing unfocused ultrasound in the left atrium and inside the pulmonary vein. Circ Arrhythm Electrophysiol 2009;2:41-9.
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25. Zellerhoff S, Ullerich H, Lenze F, et al. Damage to the esophagus after atrial fibrillation ablation: just the tip of the iceberg? High prevalence of mediastinal changes diagnosed by endosonography. Circ Arrhythm Electrophysiol 2010;3:155-9.
40. Sause A, Tutdibi O, Pomsel K, et al. Limiting esophageal temperature in radiofrequency ablation of left atrial tachyarrhythmias results in low incidence of thermal esophageal lesions. BMC Cardiovasc Disord 2010;10:52.
26. Zellerhoff S, Lenze F, Eckardt L. Prophylactic proton pump inhibition after atrial fibrillation ablation: is there any evidence? Europace 2011;13: 1219-21.
41. Perzanowski C, Teplitsky L, Hranitzky PM, Bahnson TD. Real-time monitoring of luminal esophageal temperature during left atrial radiofrequency catheter ablation for atrial fibrillation: observations about esophageal heating during ablation at the pulmonary vein ostia and posterior left atrium. J Cardiovasc Electrophysiol 2006;17:166-70.
27. Shah D, Dumonceau JM, Burri H, et al. Acute pyloric spasm and gastric hypomotility: an extracardiac adverse effect of percutaneous radiofrequency ablation for atrial fibrillation. J Am Coll Cardiol 2005;46: 327-30. 28. Pisani CF, Hachul D, Sosa E, Scanavacca M. Gastric hypomotility following epicardial vagal denervation ablation to treat atrial fibrillation. J Cardiovasc Electrophysiol 2008;19:211-3. 29. Di Biase L, Saenz LC, Burkhardt DJ, et al. Esophageal capsule endoscopy after radiofrequency catheter ablation for atrial fibrillation: documented higher risk of luminal esophageal damage with general anesthesia as compared with conscious sedation. Circ Arrhythm Electrophysiol 2009;2:108-12. 30. Yamasaki H, Tada H, Sekiguchi Y, et al. Prevalence and characteristics of asymptomatic excessive transmural injury after radiofrequency catheter ablation of atrial fibrillation. Heart Rhythm 2011;8:826-32. 31. Kennedy R, Good E, Oral H, et al. Temporal stability of the location of the esophagus in patients undergoing a repeat left atrial ablation procedure for atrial fibrillation or flutter. J Cardiovasc Electrophysiol 2008;19: 351-5. 32. Piorkowski C, Hindricks G, Schreiber D, et al. Electroanatomic reconstruction of the left atrium, pulmonary veins, and esophagus compared with the “true anatomy” on multislice computed tomography in patients undergoing catheter ablation of atrial fibrillation. Heart Rhythm 2006;3: 317-27.
42. Cummings JE, Barrett CD, Litwak KN, et al. Esophageal luminal temperature measurement underestimates esophageal tissue temperature during radiofrequency ablation within the canine left atrium: comparison between 8 mm tip and open irrigation catheters. J Cardiovasc Electrophysiol 2008;19:641-4. 43. Katsiyiannis WT, Gornick CP, Alwine ZR, Gornick CC. Esophagealatrial fistula formation despite continuous anatomic and temperature probe monitoring during ablation for atrial fibrillation. Heart Rhythm 2006;3:S283-4. 44. Rillig A, Meyerfeldt U, Birkemeyer R, et al. Oesophageal temperature monitoring and incidence of oesophageal lesions after pulmonary vein isolation using a remote robotic navigation system. Europace 2010;12: 655-61. 45. Tilz RR, Chun KR, Metzner A, et al. Unexpected high incidence of esophageal injury following pulmonary vein isolation using robotic navigation. J Cardiovasc Electrophysiol 2010;21:853-8. 46. Lemola K, Sneider M, Desjardins B, et al. Computed tomographic analysis of the anatomy of the left atrium and the esophagus: implications for left atrial catheter ablation. Circulation 2004;110:3655-60. 47. Chugh A, Rubenstein J, Good E, et al. Mechanical displacement of the esophagus in patients undergoing left atrial ablation of atrial fibrillation. Heart Rhythm 2009;6:319-22.
33. Pollak SJ, Monir G, Chernoby MS, Elenberger CD. Novel imaging techniques of the esophagus enhancing safety of left atrial ablation. J Cardiovasc Electrophysiol 2005;16:244-8.
48. Koruth JS, Reddy VY, Miller MA, et al. Mechanical esophageal displacement during catheter ablation for atrial fibrillation. J Cardiovasc Electrophysiol 2012;23:147-54.
34. Orlov MV, Hoffmeister P, Chaudhry GM, et al. Three-dimensional rotational angiography of the left atrium and esophagusea virtual computed tomography scan in the electrophysiology lab? Heart Rhythm 2007;4:37-43.
49. Buch E, Nakahara S, Shivkumar K. Intra-pericardial balloon retraction of the left atrium: a novel method to prevent esophageal injury during catheter ablation. Heart Rhythm 2008;5:1473-5.
35. Thiagalingam A, Manzke R, D’Avila A, et al. Intraprocedural volume imaging of the left atrium and pulmonary veins with rotational X-ray angiography: implications for catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol 2008;19:293-300. 36. Sherzer AI, Feigenblum DY, Kulkarni S, et al. Continuous nonfluoroscopic localization of the esophagus during radiofrequency catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol 2007;18: 157-60. 37. Okumura Y, Henz BD, Johnson SB, et al. Three-dimensional ultrasound for image-guided mapping and intervention: methods, quantitative validation, and clinical feasibility of a novel multimodality image mapping system. Circ Arrhythm Electrophysiol 2008;1:110-9. 38. Singh SM, Heist EK, Donaldson DM, et al. Image integration using intracardiac ultrasound to guide catheter ablation of atrial fibrillation. Heart Rhythm 2008;5:1548-55. 39. Martinek M, Hassanein S, Bencsik G, et al. Acute development of gastroesophageal reflux after radiofrequency catheter ablation of atrial fibrillation. Heart Rhythm 2009;6:1457-62.
50. Nakahara S, Ramirez RJ, Buch E, et al. Intrapericardial balloon placement for prevention of collateral injury during catheter ablation of the left atrium in a porcine model. Heart Rhythm 2010;7:81-7. 51. Sonmez B, Demirsoy E, Yagan N, et al. A fatal complication due to radiofrequency ablation for atrial fibrillation: atrio-esophageal fistula. Ann Thorac Surg 2003;76:281-3. 52. Doll N, Borger MA, Fabricius A, et al. Esophageal perforation during left atrial radiofrequency ablation: is the risk too high? J Thorac Cardiovasc Surg 2003;125:836-42. 53. Aupperle H, Doll N, Walther T, et al. Ablation of atrial fibrillation and esophageal injury: effects of energy source and ablation technique. J Thorac Cardiovasc Surg 2005;130:1549-54.
Supplementary Material To access the supplementary material accompanying this article, visit the online version of the Canadian Journal of Cardiology at www.onlinecjc.ca and at http://dx.doi.org/10. 1016/j.cjca.2013.12.012.
Review
Atrioesophageal Fistula in the Era of Atrial Fibrillation Ablation: A Review Girish M. Nair, MBBS, MSc, FRCPC,a Pablo B. Nery, MD,a Calum J. Redpath, MBBS, PhD, MRCP,a Buu-Khanh Lam, MD, CM, MPH, FRCSC,b and David H. Birnie, MB, ChB, MD, MRCPa a
Arrhythmia Service, Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada b
Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
ABSTRACT
RESUM E
The purpose of this review is to understand the epidemiology, clinical features, etiopathogenesis, and management of atrioesophageal fistula (AEF) after atrial fibrillation (AF) ablation. The incidence of AEF after AF ablation is 0.015%-0.04%. The principal clinical features include fever, dysphagia, upper gastrointestinal bleeding, sepsis, and embolic strokes. The close proximity of the esophagus to the posterior left atrial wall is responsible for esophageal injury during ablation. Prophylactic proton pump inhibitors, esophageal temperature monitoring, visualization of the esophagus during catheter ablation, esophageal protection devices, and avoidance of energy delivery in close proximity to the esophagus play an important role in preventing esophageal injury. Early surgical repair or esophageal stenting are the mainstay of treatment. Eliminating esophageal injury during AF ablation is of utmost importance in preventing AEF. A high index of suspicion and early intervention is necessary to prevent fatal outcomes.
pide miologie, les caLe but de cette revue est de comprendre l’e ristiques cliniques, l’e tiopathogenèse et la prise en charge de la racte fistule atrio-œsophagienne après l’ablation de la fibrillation auriculaire quence de la fistule atrio-œsophagienne après l’ablation de (FA). La fre ristiques clila FA est de 0,015 % à 0,04 %. Les principales caracte niques incluent la fièvre, la dysphagie, le saignement dans le tractus rieur, la sepsie et les accidents vasculaires gastro-intestinal supe re braux d’origine embolique. La proximite imme diate de l’œsophage ce rieure de l’oreillette gauche est responsable des et de la paroi poste sions œsophagiennes au cours de l’ablation. Les inhibiteurs de la le rature pompe à protons en prophylaxie, la surveillance de la tempe œsophagienne, la visualisation de l’œsophage au cours de l’ablation ter, les dispositifs de protection de l’œsophage et l’e vitement par cathe nergie à proximite imme diate de l’œsophage jouent un des sources d’e vention des le sions œsophagiennes. La rôle important dans la pre paration chirurgicale pre coce ou la pose d’une endoprothèse re limination des œsophagienne constituent le pilier du traitement. L’e sions œsophagiennes au cours de l’ablation de la FA est de la plus le vention de la fistule atriogrande importance dans la pre leve de suspicion et une intervention œsophagienne. Un indice e coce sont ne cessaires pour que l’issue ne soit pas fatale. pre
Atrial fibrillation (AF) is the most prevalent arrhythmia encountered in clinical practice. The prevalence of AF is 0.1% in those younger than 55 years and increases to approximately 9% in those older than 80 years. Catheter and surgical ablation procedures were introduced more than a decade ago for treatment of highly symptomatic individuals, usually younger than 75 years, with drug-refractory paroxysmal and persistent AF.
Increasing operator experience and advances in technology over the past decade have led to a dramatic rise in the number of ablation procedures worldwide.1,2 A worldwide survey on catheter ablation for AF from 182 centres in 24 countries reported 20,825 catheter ablation procedures on 16,309 AF patients between 2003 and 2006. The survey highlighted the feasibility, safety, and short- to medium-term effectiveness of catheter ablation for AF. However, the survey also listed a 4.5% risk of major complications associated with catheter ablation.3-5 The major complications associated with catheter ablation procedures for AF include cardiac tamponade, hemo- and/or pneumothorax, vascular access-related complications, stroke, pulmonary vein (PV) stenosis, atrioesophageal fistula (AEF), and death. Multiple case reports and series have described
Received for publication October 29, 2013. Accepted December 17, 2013. Corresponding author: Dr Girish M. Nair, H-1285 B, University of Ottawa Heart Institute, 40 Ruskin Ave, Ottawa, Ontario K1Y 4W7, Canada. Tel.: þ1-613-761- 4820. E-mail: [email protected] See page 394 for disclosure information.
0828-282X/$ - see front matter Ó 2014 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.cjca.2013.12.012
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AEF after catheter and surgical AF ablation. AEF has been reported after catheter ablation using radiofrequency (RF), cryoenergy, and high-frequency focused ultrasound energy.5-9 AEF is an uncommon yet invariably fatal complication of AF ablation. It results from injury to the esophagus during catheter ablation that occurs due to the close proximity of the esophagus to the posterior wall of the left atrium (LA), especially antral ablation sites.10-14 Surveys on catheter ablation for AF have reported a 0.015%-0.04% incidence of confirmed AEF after catheter AF ablation procedures. AEF is the second most common cause of mortality and accounts for 16% of cases of mortality after AF ablation. The reasons for high mortality associated with this complication is due to failure of early recognition as a result of lack of clinical awareness, delayed presentation, and complex surgical repair required for treatment.3-5,9,15,16 Although thoracic surgeons and gastroenterologists have long been aware of AEF as a complication after gastroesophageal surgery, cardiologists had never encountered this potentially lethal complication until the advent of catheter ablation for AF. This review addresses the rare, albeit potentially fatal, complication of AEF after AF ablation procedures and aims to provide the clinician with an overview of the clinical presentation, etiopathogenesis, and management of this condition. Clinical Case Examples The cases presented highlight the clinical presentations of AEF after catheter ablation for AF. Case 1 A 63-year-old man presented to the emergency department (ED) with history of high-grade fever associated with chills and rigours for 4 days. While being evaluated in the ED he had massive hematemesis leading to circulatory collapse and death. He had complained of retrosternal pain, aggravated while swallowing food, for a week before the presentation. Six weeks before the event he had undergone a catheter ablation for AF. Autopsy revealed an AEF (see Fig. 1), infective endocarditis, and abscesses in multiple internal organs.
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Case 2 A 62-year-old woman presented to the ED with confusion, weakness of the left half of the body, and high-grade fever with chills and rigours. Magnetic resonance imaging (MRI) of the brain revealed multiple septic emboli. The patient had catheter ablation for AF 4 weeks before presentation. Contrast enhanced computed tomography (CT) scan revealed evidence of AEF (see Fig. 2). Autologous pericardial patch repair of the AEF, from the endocardial surface of the LA, was performed under cardiopulmonary bypass (see Fig. 3). After this, an upper gastrointestinal (UGI) endoscopy was performed, which revealed esophageal ulceration (Fig. 4). Surgical repair of the esophageal aspect of the AEF was performed using a pleural flap. The patient needed intensive care along with broad-spectrum antibiotics for sepsis. This case demonstrates the need for early detection and treatment along with close cooperation between emergency physicians, cardiologists, radiologists, and cardiac and thoracic surgeons. Clinical Features and Diagnostic Investigations AEF typically presents between 2 and 6 weeks after catheter ablation. Common clinical features of AEF include dysphagia, nausea, heartburn, hematemesis or melena, high fever, sepsis, pericardial or pleural effusions, mediastinitis, seizures, and strokes.15,17,18 A high degree of clinical suspicion for esophageal injury and possible AEF should be entertained in patients presenting with the clinical features described and a recent history of AF ablation. Leukocytosis is one of the earliest and most sensitive laboratory markers in almost all patients with AEF.15 UGI endoscopy should be avoided in patients suspected to have AEF because massive cerebral air embolization has been reported after air insufflation during endoscopy.15 Thoracic CT scan is the investigation of choice in patients with suspected AEF and the radiological features include pericardial effusion, intravascular air, inflammation of atrial and esophageal tissue, frank communication between the atrium and the pericardium or the esophagus, and extensive systemic septic or food emboli.15-19
Figure 1. Autopsy specimen of the left atrium from a patient with atrioesophageal fistula after atrial fibrillation ablation. The location of the atrioesophageal fistula is at the ablation site in the posterosuperior aspect of the antrum of the left common pulmonary vein. Image courtesy of Jennifer Walsh, MD, FRCPC, Chief, Laboratory Medicine, Halton Healthcare Services, Oakville, ON, Canada.
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Figure 2. Computed tomography images (unenhanced and contrast-enhanced) showing air in the left atrium and pericardial cavity. In addition a clot, partially occluding the atrioesophageal fistula at the level of the left superior pulmonary vein, is seen in the left atrium.
Pathophysiology of AEF The close anatomic relationship of the esophagus and the LA is the most important factor responsible for the pathogenesis of esophageal mucosal injury during AF catheter ablation. The esophagus is situated in a groove posterior to the LA, bounded by the aorta on the left and the vertebral column
posteriorly. The esophagus follows a variable course and might be encountered adjacent to the left or right PVs or the mid portion of the posterior LA wall. In addition, the posterior LA wall, the fat pad, and connective tissue layer between the LA and the esophagus have variable thickness. Patients with LA dilatation have thinner fat pads and a larger contact area
Figure 3. Surgical photographs showing the site of the atrioesophageal fistula, autologous pericardial patch repair, and clots extracted from the left atrium that were partially occluding the fistula.
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Figure 4. Upper gastrointestinal endoscopy during surgical repair of an atrioesophageal fistula demonstrating esophageal mucosal injury.
between the esophagus and the LA. This region contains vascular structures, branches of the vagus nerve, and lymph nodes. Injury to these structures during AF catheter ablation is though to contribute to the genesis of AEF.20-23 The delayed presentation after AF ablation (2-6 weeks) makes it unlikely that mechanical perforation of the atrial wall during catheter ablation is a mechanism responsible for development of AEF. A canine model of esophageal injury and AEF after applications of ultrasound energy in the LA demonstrated that luminal esophageal temperature (LET) in excess of 50 C resulted in transmural esophageal necrosis with ulceration. High LET ( 50 C) resulting in esophageal ulceration occurred only when energy was applied in the LA within 2 mm of the esophagus.24 Thermal injury is thought to affect the microvasculature of esophageal tissue leading to ischemic necrosis of the mucosal layers. Damage to esophageal connective tissue and posterior LA wall has been noticed on endosonography after AF catheter ablation.25 The progression of esophageal ulceration to ultimate AEF formation was associated with gastric hypomotility, pyloric spasm, esophagitis, and lower esophageal sphincter relaxation, as a consequence of periesophageal vagal plexus injury and resultant acid reflux.25-28 UGI and capsule endoscopy have shown a 2%-20% incidence of esophageal injury in human subjects after catheter ablation for AF.10-12,19,29 Halm and colleagues found asymptomatic esophageal injury in 15% of subjects undergoing UGI endoscopy after catheter ablation for AF or left atrial tachycardia. The lesions varied in size from 2 to 16 mm. The authors found that subjects with intraluminal esophageal temperatures less than 41 C during catheter ablation did not show endoscopic evidence of esophageal injury. Subjects with esophageal signs of mucosal injury had greater LET (42.6 1.7 C vs 41.4 1.7 C). The odds of esophageal injury increased by a factor of 1.36 for every 1 C increase in LET.11 Di Biase and colleagues used capsule endoscopy after AF catheter ablation and detected a 17% incidence of mucosal esophageal injury.12 The same group also explored the relationship between esophageal injury and the type of anaesthesia used during AF catheter ablation. They found a 48% incidence of esophageal mucosal injury in patients undergoing AF catheter ablation under general anaesthesia compared with a 4% incidence in those receiving conscious sedation. In this study the LET in the general anaesthesia group was higher than the local
anaesthesia group (40.6 1 C vs 39.6 0.8 C). Reduced esophageal peristaltic movement and lack of swallowing along with use of a nasogastric tube leading to fixation of the esophagus were thought to be responsible for the increased incidence of esophageal injury in the general anaesthesia group.29 Martinek and colleagues found proximity of the esophagus to the LA posterior wall (3-5 mm) to be a marker for esophageal injury in human subjects. The esophagus is sandwiched between the LA anteriorly, and the thoracic vertebral column and aorta posteriorly; especially in patients with dilated LA. This is thought to contribute to esophageal compression and increased risk of esophageal injury. In addition extensive ablation in the posterior wall of the LA and higher RF energy (25 W compared with 15 W) were associated with increased incidence of esophageal injury. However, general anaesthesia was not associated with an increase in the risk of esophageal injury compared with conscious sedation in this study (2.7% vs 2.2%).10,14 The presence of gastroesophageal reflux associated with catheter ablation is thought to contribute to esophageal injury. Esophageal ulceration is thought to result in mediastinitis, erosion of the pericardium, and posterior LA wall AEF formation.24,26 Yamasaki and colleagues performed UGI endoscopy in 104 patients 48 hours after AF catheter ablation to detect esophageal injury. The subjects had undergone AF catheter ablation under conscious sedation with a maximum energy of 20-25 W, using irrigated tip catheters, for a maximum duration of 30 seconds on the posterior wall of the LA. Some subjects (9.6%) were found to have esophageal injury. All subjects with esophageal injury had body mass index < 24.9. The proposed explanation for this finding was that the posterior LA wall was closer to the esophagus in individuals with normal body mass index and that they had less connective tissue between the esophagus and the LA leading to a greater chance of mucosal thermal injury.30 Prevention of Esophageal Injury Imaging the esophagus before ablation Imaging the esophagus (CT/MRI scans) and visualizing its course in relation to ablation sites in the posterior wall of the
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LA or the coronary sinus plays an important role in prevention of esophageal injury (see Fig. 5). Kennedy and colleagues obtained cine-fluoroscopic images during swallowed barium contrast to record the course of the esophagus prior to repeat catheter ablation. The images were tagged on the 3D map during repeat ablation and the position of the esophagus, relative to the PVs, was found to be identical to its position during the initial procedure.31 Piorkowski and colleagues found excellent correlation between the location of the esophagus, determined on preprocedural CT scan, and its intraprocedure position determined using electroanatomic mapping systems.32 Three-dimensional rotational CT or MRI scans using swallowed barium or gadolinium contrast are also used to improve visualization of the esophagus. However, these methods display the esophageal location before or on the day of the procedure. The position of the esophagus is quite variable and might change by as much as 15 mm, limiting the usefulness of imaging in some situations.33-35 Threedimensional real-time images of the esophagus generated using electroanatomic mapping systems or intracardiac echocardiography can be used to avoid ablation in the LA within 3-5 mm of the esophagus. Real-time imaging has the advantage of detecting changes in esophageal position during the ablation procedure, allowing the operator to adjust ablation sites to avoid the esophagus.36-38 Esophageal mucosal protection Esophageal injury after atrial ablation lesions has been demonstrated in a canine model.24 UGI endoscopy after catheter ablation for AF has demonstrated a 2%-20% incidence of esophageal injury and mucosal ulceration.10,12,14,29 Esophageal mucosal injury has been shown to lead to progressive ulceration ultimately resulting in the development of AEF.39 Patients with esophageal injury are aggressively treated with proton pump inhibitors (PPIs) and undergo enhanced surveillance for features suggestive of AEF.10,12 Insights into the etiopathogenesis of AEF and the knowledge that esophageal injury is a precursor of AEF have prompted prophylactic PPI therapy for patients undergoing catheter ablation.
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However, the effectiveness of PPI therapy in preventing AEF in ablation patients is unlikely to be tested in prospective, randomized trials because of the very low incidence of this complication.26 Techniques to prevent esophageal injury during catheter ablation LET monitoring. A temperature probe in the esophagus, positioned as close as possible to the ablation catheter, can alert the ablator to increases in LET. This information can be used to titrate or interrupt energy delivery. Singh and colleagues performed a retrospective comparison of esophageal mucosal injury in patients undergoing AF catheter ablation with and without LET monitoring during AF catheter ablation. The group undergoing ablation with LET monitoring had ablation energy limited or interrupted when the temperature reached 38.5 C. There was a significantly lower incidence of esophageal injury in the monitored group compared with the unmonitored group (6% vs 36%).19 Sause and colleagues used a special triple-thermocouple LET monitor during AF catheter ablation to limit energy delivery to a luminal temperature of 40 C. Only 1.6% of subjects enrolled in the study developed esophageal mucosal injury.40 Perzanowski and colleagues performed LET monitoring using a deflectable catheter. The recording tip was positioned as close as possible to the site of ablation on the posterior LA wall. Ablation was limited to 25 W and was interrupted when the LET increased by 2 C. None of the subjects included in this study developed mucosal injury during follow-up. However, the LET might not be reliable if the temperature catheter is not close to the ablation site or if the esophagus is large. The esophageal temperature might continue to increase in most patients even after RF delivery is interrupted.41 LET might be significantly lower than esophageal mural temperature and esophageal mucosal injury might occur even after temperature monitoring, resulting in AEF.29,42,43 LET monitoring, though very effective in reducing esophageal mucosal injury, might not be sufficient to eliminate esophageal injury and AEF because of its limitations.
Figure 5. Three-dimensional computed tomography reconstruction demonstrating the close proximity of the esophagus to the posterior wall of the left atrium. In this case, the esophagus is located immediately behind the left pulmonary veins.
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Limiting energy delivery on the posterior LA wall. Limiting the energy delivered using open-irrigated ablation catheters to 25-30 W on the posterior LA wall has been shown to reduce esophageal mucosal injury.10,11,40 Rillig and colleagues found significant LET increase in most (76%) subjects undergoing AF catheter ablation using a robotic navigation system. After ablation, 14% of subjects were found to have esophageal mucosal injury on endoscopic examination after the procedure.44 Tilz and colleagues compared robotic navigation (RN)-assisted catheter ablation with manual catheter ablation in human subjects. Subjects underwent RN-assisted catheter ablation with a power setting of 30 W or 20 W, contact force between 10g and 40g, and open irrigation at 17 mL/m2. Ablation was terminated if LET reached 41 C. Almost all patients in the 30 W arm developed esophageal mucosal injury detected using endoscopic examination and 1 patient went on to develop esophageal perforation. Only 12% of patients in the manual ablation arm and 1 patient in the 20 W RN ablation arm developed esophageal mucosal injury. This study highlights the need for limiting energy delivery during ablation on the posterior LA wall.45 Force-sensing catheters and other tools to directly visualize the posterior wall of the LA during ablation might help to reduce the incidence of esophageal mucosal injury. Mechanical deflection of the esophagus during catheter ablation. The anatomical course of the esophagus behind the posterior wall of the LA and the coronary sinus puts it at risk for injury during catheter ablation.20,21 The distance between the posterior LA wall and the esophagus was found to be < 5 mm in 40% of autopsy specimens.20 Lemola and colleagues used CT scans to demonstrate that the fat pad intervening between the esophagus and the posterior LA wall is discontinuous in most subjects and is variable in its thickness (0.31.3 mm; 0.9 0.2 mm).46 Mechanical displacement of the esophagus to move it away from the site of LA posterior wall ablation has been used to limit mucosal injury. Chugh and colleagues used a deflectable UGI endoscope to deflect the esophagus away from the site of ablation. However, the endoscope had to be removed before energy delivery to avoid shunting of RF energy. After removal of the endoscope, the esophagus remained in the displaced position in very few subjects, making it unlikely that this technique was effective. Real-time imaging was not used in this study to ascertain if the esophagus was merely stretched using the endoscope or actually displaced away from the ablation site.47 Koruth and colleagues used an endotracheal stylet introduced into a thoracic chest tube to deflect the esophagus away from ablation sites in the LA. This technique allowed the esophagus to be moved 2.8 cm on average. LET monitoring was performed during ablation and showed that the esophageal temperature did not increase to > 40 C in any subject. One subject (5%) with an unusual atrial diverticulum overlying the posterior LA wall developed mucosal injury after ablation. Twelve (63%) patients showed signs of esophageal trauma related to instrumentation. However, none of these patients had any clinical sequelae.48 These case series seem to suggest that mechanical displacement of the esophagus during AF catheter ablation might limit mucosal injury. However, it will be very difficult to prove that this reduction in esophageal
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mucosal injury can reduce the incidence of AEF because of the low incidence of this complication. Esophageal insulation from thermal injury. Thermal insulation of the esophagus by inserting a removable barrier between the posterior LA wall and the esophagus is another strategy used to limit mucosal injury. Buch and colleagues positioned a fluid-filled balloon catheter, using a percutaneous pericardial approach, into the oblique sinus to move the esophagus away from the LA. This intervention allowed PV isolation without esophageal heating or injury in a patient in whom a previous PV isolation procedure had to be aborted because of esophageal luminal heating.49 Nakahara and colleagues evaluated this technique in a porcine model to demonstrate that an intrapericardial balloon, interposed between the esophagus and the LA, consistently allowed prevention of LET increase. The presence of the fluid-filled balloon in the pericardial space did not result in hemodynamic compromise.50 It might be difficult to use this technique routinely during AF ablation procedures because of the need for percutaneous pericardial access and the possibility of associated complications such as bleeding and infection. However, it can be used in select individuals in whom PV isolation cannot be achieved because of LET increase. Treatment of AEF A high index of suspicion should be exercised by treating physicians for early identification of patients with AEF. A wallet card listing the clinical features of AEF and the need for diagnostic imaging with CT scan might help alert patients and emergency physicians to recognize this condition early and intervene expeditiously (see Supplemental Fig. S1). Immediate surgery after onset of symptoms might help prevent fatalities and other serious outcomes such as air and food embolism. The surgical technique usually involves a combined cardiac and thoracic approach under cardiopulmonary bypass. The atrial aspect of the AEF is repaired using autologous pericardial patch and the esophageal aspect is repaired using a pleural or muscular flap.51-53 Adjunctive care with antibiotics and nutritional support in an intensive care setting is critical. An expectant management strategy including intravenous antibiotics has been shown to be associated with poor outcomes.15,16,18 Successful nonsurgical treatment in 3 cases of AEF with esophageal stenting and pericardiocentesis has been reported. The esophageal stents were removed after complete resolution of the AEF. Close communication with the gastroenterologist, and thoracic and cardiac surgeons is critical to successful management of patients with AEF.17,18 Summary AEF after AF ablation is an uncommon yet catastrophic complication almost always associated with a fatal outcome. Prevention of esophageal injury during ablation is of utmost importance. Strategies to identify the esophagus and avoidance of energy delivery in close proximity to the esophagus, esophageal protection devices, and esophageal temperature monitoring are the most important preventive strategies that should be considered during catheter ablation. Prophylactic proton pump inhibitor therapy for esophageal mucosal
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protection has been shown to be effective in preventing esophageal injury. Patient and physician education to recognize early symptoms and signs of AEF is important. Early definitive surgical intervention or nonsurgical esophageal stenting is recommended in patients with AEF. The possibility of fatal complications such as AEF, strokes, and death might be the reason that current guidelines recommend catheter ablation only for high burden, symptomatic AF patients refractory to antiarrhythmic medications. Acknowledgements The authors thank Dr Jennifer Walsh for providing autopsy photographs from a patient who developed AEF after catheter ablation for AF. Disclosures The authors have no conflicts of interest to disclose. References 1. Calkins H, Kuck KH, Cappato R, et al. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, end points, and research trial design: a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation. Developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology (ESC) and the European Cardiac Arrhythmia Society (ECAS); and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). Endorsed by the governing bodies of the American College of Cardiology Foundation, the American Heart Association, the European Cardiac Arrhythmia Society, the European Heart Rhythm Association, the Society of Thoracic Surgeons, the Asia Pacific Heart Rhythm Society, and the Heart Rhythm Society. Heart Rhythm 2012;9:632-696.e21.
Canadian Journal of Cardiology Volume 30 2014 9. Ghia KK, Chugh A, Good E, et al. A nationwide survey on the prevalence of atrioesophageal fistula after left atrial radiofrequency catheter ablation. J Interv Card Electrophysiol 2009;24:33-6. 10. Martinek M, Bencsik G, Aichinger J, et al. Esophageal damage during radiofrequency ablation of atrial fibrillation: impact of energy settings, lesion sets, and esophageal visualization. J Cardiovasc Electrophysiol 2009;20:726-33. 11. Halm U, Gaspar T, Zachaus M, et al. Thermal esophageal lesions after radiofrequency catheter ablation of left atrial arrhythmias. Am J Gastroenterol 2010;105:551-6. 12. Di Biase L, Dodig M, Saliba W, et al. Capsule endoscopy in examination of esophagus for lesions after radiofrequency catheter ablation: a potential tool to select patients with increased risk of complications. J Cardiovasc Electrophysiol 2010;21:839-44. 13. Lemery R. Left atrial anatomy, energy delivery and esophageal complications associated with ablation of atrial fibrillation. J Cardiovasc Electrophysiol 2010;21:845-8. 14. Martinek M, Meyer C, Hassanein S, et al. Identification of a high-risk population for esophageal injury during radiofrequency catheter ablation of atrial fibrillation: procedural and anatomical considerations. Heart Rhythm 2010;7:1224-30. 15. Dagres N, Kottkamp H, Piorkowski C, et al. Rapid detection and successful treatment of esophageal perforation after radiofrequency ablation of atrial fibrillation: lessons from five cases. J Cardiovasc Electrophysiol 2006;17:1213-5. 16. Dagres N, Hindricks G, Kottkamp H, et al. Complications of atrial fibrillation ablation in a high-volume center in 1,000 procedures: still cause for concern? J Cardiovasc Electrophysiol 2009;20:1014-9. 17. Eitel C, Rolf S, Zachaus M, et al. Successful nonsurgical treatment of esophagopericardial fistulas after atrial fibrillation catheter ablation: a case series. Circ Arrhythm Electrophysiol 2013;6:675-81. 18. Singh SM, d’Avila A, Singh SK, et al. Clinical outcomes after repair of left atrial esophageal fistulas occurring after atrial fibrillation ablation procedures. Heart Rhythm 2013;10:1591-7.
2. Verma A, Macle L, Cox J, Skanes AC, Committee CCSAFG. Canadian Cardiovascular Society atrial fibrillation guidelines 2010: catheter ablation for atrial fibrillation/atrial flutter. Can J Cardiol 2011;27:60-6.
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3. Cappato R, Calkins H, Chen SA, et al. Worldwide survey on the methods, efficacy, and safety of catheter ablation for human atrial fibrillation. Circulation 2005;111:1100-5.
20. Sanchez-Quintana D, Cabrera JA, Climent V, et al. Anatomic relations between the esophagus and left atrium and relevance for ablation of atrial fibrillation. Circulation 2005;112:1400-5.
4. Cappato R, Calkins H, Chen SA, et al. Updated worldwide survey on the methods, efficacy, and safety of catheter ablation for human atrial fibrillation. Circ Arrhythm Electrophysiol 2010;3:32-8.
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Supplementary Material To access the supplementary material accompanying this article, visit the online version of the Canadian Journal of Cardiology at www.onlinecjc.ca and at http://dx.doi.org/10. 1016/j.cjca.2013.12.012.
