Introduction: Radiofrequency ablation (RFA) is a catheter based ablation technique used in patients with atrial fibrillation(AF) to achieve rhythm control.There is risk of esophageal thermal injury during RFA to the posterior left atrium given its close proximity to the anterior esophagus.We describe a case of thermal injury to the esophagus following RFA therapy to the left atrium. Case Report: A 69-year-old female with a history of hypertension, AF was seen with a two day history of melena.The patient's melenic stools began one day following RFA therapy.The patient reported a “gassy feeling” in her stomach but denied abdominal pain,nausea,vomiting,chest pain,heartburn,dysphagia,o dynophagia,fever/chills.No history of GI bleed or change in stool consistency/color were reported in the past.On exam patient was afebrile,hypertensive(178/78) with heart rate of 80. Abdomen was soft/nontender/nondistended with normoactive bowel sounds, no abdominal masses, organomegaly. Lungs were clear to ausculation as no abnormal heart sounds were noted. Lab results demonstrated Potassium 3.5mmol/L,Sodium 142mmol/L,Chloride 102mmol/L,hemoglobin 13.9 g/dL,platelet count 219 10(3)/mcl,PT 15.6, INR 1.4,PTT 31.5.Liver enzymes were normal.An EGD demonstrated a 6-7 mm healing ulcer in the mid esophagus with no evidence of active bleeding.The submucosa was not seen and no evidence of perforation was noted.She was discharged home with pantoprazole 40mg twice daily,sucralfate 1g four times daily and instructions to follow up in the GI clinic. Discusion: Esophageal injury is one complication of RFA therapy.This is due to the close anatomical proximity between the esophagus and the posterior LA wall which is estimated to be ≤ 5 mm in 40% of the population.The intestinal tissue is also far more susceptible to radiofrequency induced thermal injury than the muscular tissue of the heart. Therefore,direct contact of a probe is not required for thermal injury, as convection heat generated within the LA is enough energy to cause esophageal injury.Early diagnosis is vital to prevent fatal outcomes from complication such as perforation and fistula formation. Atrial fibrillation is projected to surge 2.5-fold in the near future due to the aging demographic leading to an increase use of RFA therapy. This may result in a higher incident of RFA related thermal esophageal injury.Further research is needed to identify risk factors,preventive strategies and optimal treatment for esophageal thermal injury related to left atrial RFA.Figure 1