An atrioesophageal fistula is a very rare (incidence rate of 0.03%-0.08%, although this may be an underestimate due to underreporting or misdiagnosis) but often fatal complication of atrial fibrillation ablation procedures resulting from profound thermal injury to the esophagus (due to its close proximity to the posterior wall of the left atrium, and also a larger left atrium-esophageal contact area often seen in people with atrial fibrillation and left atrial dilatation compared to those without such conditions) and surrounding structures. As development of a fistula is not instantaneous, this complication is considered to be late/delayed, with median time from ablation procedure to clinical presentation of 21d (most common time range for presentation being 2-4 weeks post-procedure). The most common findings include fever (73%) and neurological symptoms (72%), which were defined as at least one of the following: seizure, confusion, loss of consciousness, and/or focal neurologic deficits. Less common symptoms include GI symptoms (41%) (including one or more of the following: hematemesis/melena, dysphagia/odynophagia, and/or nausea/vomiting) and chest pain (~35%). Urgent treatment is essential and can include surgery or endoscopic intervention; even so, overall mortality is estimated to be 55%.
References: Atrioesophageal Fistula: Clinical Presentation, Procedural Characteristics, Diagnostic Investigations, and Treatment Outcomes