Left Atrial Ablation for Atrial Fibrillation is safe and effective for most patients. However a rare complication is thermal damage to the integrity of the normal physical barriers between the left atrium and the adjacent oesophagus due to the ablation process. This can lead to formation of an Atrial-Oesophageal fistula with sepsis, haemorrhage and systemic cardioembolism occurring even up to 2 months post procedure. The presentation is similar to endocarditis but localised instrumentation specifically Transoesophageal echocardiography (TOE) can provoke systemic cardioembolism. This is an important differential in those presenting acutely with a Pyrexia of Unknown Origin or endocarditis-like picture within 2 months of ablation therapy.