INTRODUCTION: Esophageal-pericardial fistulas are rare complications which can arise from many different pathologies, such as ulcerations, diverticulum, foreign bodies, carcinomas, radiofrequency atrial ablation, or prior surgeries It may be difficult to recognize due to vague symptoms such as pain, fever, nausea, hematemesis, dysphagia, or odynophagia Even when promptly recognized, the mortality rate is often around 80% CASE DESCRIPTION/METHODS: A 61 year old female with a past medical history significant for RA, hypothyroidism, bariatric surgery, gastrectomy with gastric pouch, gastric and esophageal ulcers presented to the ED for an evaluation of altered mental status During a long hospital stay, which included intubation and a short ICU stay, she was found to have pneumopericardium on a routine chest X-ray A CT chest without contrast was done to confirm The pneumopericardium was not causing any hemodynamic instability and therefore was treated conservatively with IV antibiotics A repeat CT was performed the following morning which showed resolving pneumopericardium and therefore no surgery was indicated Initially the pneumopericardium was believed to be from a fistula from the trachea to the pericardium, presumed due to intubation, however, a barium swallow was performed and showed a fistula formation between the esophagus and pericardium No surgery was indicated and the patient was on appropriate GI prophylaxis The patient was placed on TPN until a PEG could be initiated She remained stable and was discharged to a long term care facility with a plan for follow up EGD in 8 weeks The patient has not yet followed up due to the COVID-19 pandemic DISCUSSION: Here we presented a case of an esophageal-pericardial fistula with unknown origin We presume in our patient, the fistula developed over time due to her long standing GERD, prolonged NSAID use, and known esophageal ulcers Esophageal-pericardial fistulas are associated with a high morbidity and mortality, and making an early diagnosis is crucial Patients with pericardial fistulas often complain of chest pain or abdominal pain but can have a wide range of more non-specific symptoms including dyspnea, fever, cough, and even sputum production It is important to have a high index of suspicion and avoid a delay in the diagnosis, especially if there are risk factors present This case highlights an example of a patient with a highly fatal diagnosis, who remained hemodynamically stable and relatively asymptomatic during her hospital course (Figure Presented)