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A Bitter Pill to Swallow: Esophageal Lesions After PVI May Not Be What We Expected LORNE J. GULA, M.D., F.R.C.P.C. and ALLAN C. SKANES, M.D., F.R.C.P.C. From the Arrhythmia Service, University Hospital, Western University, London, Ontario, Canada

atrial fibrillation, ablation, complications Editorial Comment Pulmonary vein isolation (PVI) has rapidly become a common procedure for management of atrial fibrillation (AF). With a success rate higher than antiarrhythmic medication and a relatively low risk, ablation is now a reasonable consideration for most patients with AF. The main argument against routine use of ablation as first line therapy for AF is the rare but real risk of life-threatening complications. Among the most concerning of the potential late complications is atrialesophageal fistula. This complication is difficult to study given its fortunately low incidence, with 5 fistulas reported among 45,115 procedures in a study of 546 worldwide centers.1 But with a mortality rate close to 100%—a recent report2 detailed deaths in all 5 patients within a week of esophageal stenting, in contrast to 2+ year survival in all 4 patients undergoing surgery within 4 hours of diagnosis—it has remained a high priority to attempt to study, understand, and prevent this devastating complication. As with any condition that is too rare to study directly, many investigators have looked to a surrogate outcome, in this case mucosal erosions and ulceration detected by esophageal imaging after ablation. We have been tempted to consider such ulcers as minor forms of potential fistulas, and therefore investigate these lesions with the belief that we are learning more about the full blown condition. But it seems we may need to learn more about the ulcers themselves, specifically whether a subset of these lesions are in fact due to mechanical trauma from a TEE probe and unrelated to ablation. TEE has been a routine adjunct to PVI in some centers to facilitate transseptal access and to monitor for complications. Intraprocedural TEE has been gradually replaced in most centers by electroanatomic imaging to assess catheter position in the left atrium, and by intracardiac echocardiography to facilitate transseptal access either on a routine basis or for cases where routine fluoroscopy and contrast injection is deemed insufficient. Preprocedural TEE surveillance for left atrial (LA) clot remains the standard of care in high risk patients, and is also used routinely in some centers. We have previously presented modeling that suggests routine preablation TEE has an absolute risk reduction of 1.2% for stroke J Cardiovasc Electrophysiol, Vol. 26, pp. 127-128, February 2015. No disclosures. Address for correspondence: Lorne Gula, M.D., F.R.C.P.C., Arrhythmia Service, Rm C6-110, University Hospital, 339 Windermere Road, London, Ontario, Canada, N6A 5A5. E-mail: [email protected] doi: 10.1111/jce.12594

with a number needed to treat of 84 and incremental cost effectiveness ratio $2,232 per quality adjusted life year. All of these factors need to be considered in determining the role of TEE in PVI, and in this issue of the Journal, Kumar et al.3 present a study addressing the potential risks of ablation-related TEE imaging. In fact, they do this in a very progressive manner, using a relatively new and novel technology, capsule endoscopy, to assess the risk of a traditional technology, TEE. Their group initially noted a signal of esophageal injury,4 in the form of hematomas, in a prospective assessment of 1,110 AF ablations performed under general anesthesia (GA) with TEE. Three patients (0.27%) developed esophageal hematoma heralded by early symptoms of hoarseness, regurgitation, and difficulty swallowing. These patients suffered long-term effects including esophageal stricture, dysmotility, and persistent hoarseness related to vocal cord paralysis. To further assess, they designed the present study with 3 groups for comparison—76 paroxysmal AF patients undergoing PVI with TEE, 16 paroxysmal AF patients undergoing PVI without TEE, and 27 persistent AF or atrial flutter patients with TEE and no LA ablation. Patients underwent esophageal capsule endoscopy using a “pill cam” in the week prior to, and again 24 hours after, the procedure. Imaging was repeated within 2 weeks if ulceration was detected. The pill cam detected esophageal lesions in 29 (24%) patients, consisting mainly of erosions and ulcerations in the upper and mid esophagus. Among these 29 patients, 6 experienced symptoms, and 8 patients underwent repeat esophageal imaging, demonstrating that all lesions had resolved within 2 weeks. The provocative result of the study was the incidence of esophageal lesions according to TEE. Lesions were detected in 30% of 76 patients who had a TEE probe in place during LA ablation, 22% of 27 patients with TEE but no LA ablation, and in none of 16 patients with PVI who did not undergo TEE. As discussed by the investigators, the groups are small and the estimates of incidence therefore have wide confidence intervals—an event rate of 0 in a sample of 16 patients, for example, has a 95% binomial confidence interval that extends beyond 19%. But even if this casts doubt on the accuracy of the estimates, the finding of any esophageal lesions in TEE patients without ablation, at an incidence similar to those with LA ablation, certainly indicates that the TEE probe is the cause of at least some esophageal damage. With this in mind, the dilemma for the AF ablation community is the validity of using these lesions as surrogate markers for atrialesophageal fistula. For example, those who tout the benefits of esophageal temperature monitoring during ablation may cite a recent study5 in which esophageal injury was observed in 36% of those without temperature monitoring compared

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with 6% with monitoring. However, this result may be more challenging to interpret knowing that 14/14 nonmonitored patients had a TEE on the day of ablation, compared with 15/67 monitored patients. Was the higher incidence of injury without temperature monitoring, at least in part, due to the higher incidence of preprocedure TEE? Similarly, Di Biase et al.6 investigated the relationship between GA and esophageal lesions detected by capsule endoscopy. Fifty patients were studied, half receiving GA and half conscious sedation during ablation for paroxysmal AF. Esophageal examination the day following the procedure demonstrated a 48% incidence of esophageal lesions with GA and 4% incidence with conscious sedation (P < 0.001). All lesions had resolved by 2 months on repeat imaging. This certainly suggests a higher incidence of esophageal lesions due to GA. It is not clear, however, if TEE was a factor in this study and, if so, whether it was differentially used between groups. The interpretation of this type of study becomes more challenging in view of Kumar et al., as the possibility of TEE induced damage may be an important confounding factor. It is certainly reasonable to use a surrogate endpoint in our studies intended to characterize and prevent rare but lethal conditions. Ideally, such a surrogate should predict or be strongly associated with the endpoint, and they should lie along a common causal pathway. At a minimum, the relationship between the two should be well understood. With this in mind, the study by Kumar et al. gives us reason to reflect on our use of minor postablation esophageal lesions as surrogates of devastating esophageal fistulas. Indeed, the pathophysiology of fistulas themselves is unclear—are they a result of direct heating, avascular necrosis, or some other mechanism? In addition, there is now reason to question the nature of ulcers and erosions detected on esophageal imaging. Do lesions that are caused by mechanical trauma from the TEE probe share a common natural history and relationship to fistulas as those caused by ablation? This is a critical question if the point of the investigation is not detection of transient, benign, asymptomatic esophageal injuries but

rather an attempt to glean the causes and ultimately prevent the rare but fatal complication of atrial-esophageal fistula. Research that sheds new light on the status quo and our clinical assumptions is valuable research indeed. Kumar et al. do this in 2 respects, making us rethink the value of TEE during PVI in light of potential harm and viable alternatives, and exercise caution in drawing conclusions based on esophageal lesions detected after PVI. References 1. Cappato R, Calkins H, Chen SA, Davies W, Iesaka Y, Kalman J, Kim YH, Klein G, Natale A, Packer D, Skanes A: Prevalence and causes of fatal outcome in catheter ablation of atrial fibrillation. J Am Coll Cardiol 2009;53:1798-1803. 2. Mohanty S, Santangeli P, Mohanty P, Di Biase L, Trivedi C, Bai R, Horton R, Burkhardt JD, Sanchez JE, Zagrodzky J, Bailey S, Gallinghouse JG, Hranitzky PM, Sun AY, Hongo R, Beheiry S, Natale A: Outcomes of atrioesophageal fistula following catheter ablation of atrial fibrillation treated with surgical repair versus esophageal stenting. J Cardiovasc Electrophysiol 2014;25:579-584. 3. Kumar S, Brown G, Sutherland F, Morgan J, Andrews D, Ling LH, McLellan AJ, Lee G, Robinson T, Heck P, Halloran K, Morton J, Kistler P, Kalman JM, Sparks PB: The transesophageal echo probe may contribute to esophageal injury after catheter ablation for paroxysmal atrial fibrillation under general anesthesia: A preliminary observation. J Cardiovasc Electrophysiol 2015;26:119-126. 4. Kumar S, Ling LH, Halloran K, Morton JB, Spence SJ, Joseph S, Kistler PM, Sparks PB, Kalman JM: Esophageal hematoma after atrial fibrillation ablation: Incidence, clinical features, and sequelae of esophageal injury of a different sort. Circ Arrhythm Electrophysiol 2012;5:701705. 5. Singh SM, d’Avila A, Doshi SK, Brugge WR, Bedford RA, Mela T, Ruskin JN, Reddy VY: Esophageal injury and temperature monitoring during atrial fibrillation ablation. Circ Arrhythm Electrophysiol 2008;1:162-168. 6. Di Biase L, Saenz LC, Burkhardt DJ, Vacca M, Elayi CS, Barrett CD, Horton R, Bai R, Siu A, Fahmy TS, Patel D, Armaganijan L, Wu CT, Kai S, Ching CK, Phillips K, Schweikert RA, Cummings JE, Arruda M, Saliba WI, Dodig M, Natale A: 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;2:108-112.

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A bitter pill to swallow: esophageal lesions after PVI may not be what we expected.

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