Infective endocarditis (IE) following transcatheter aortic valve replacement (TAVR) has been associated with a poor prognosis. The development of an aorto–atrial fistula (AAF) is a rare but problematic complication of IE, which can be confirmed with transesophageal echocardiography. A 55–year–old man, asthmatic and allergic (Penicillin and ASA) went to the emergency room for therapy–resistant hyperpyrexia and was admitted to Medicine Department for the necessary investigations and treatment. In remote pathological history: ischemic heart disease with dilated–hypokinetic evolution, already revascularized by CABG in 1996 and by PTCA in 2006 and in 2016; transcatheter aortic valve replacement with biological prosthesis in 2018. In the next medical history: admission to neurosurgery about 9 months before for cerebral haemorrhage and implantation of CRT– ICD about 6 months before On the echocardiogram performed at the entrance, evidence of isoechoic formation on the mitral flap for which further study with TEE was recommended. Blood cultures performed during hospitalization were positive for S. Epidermidis Oxacillin resistant. Few days after the admission, due to a sudden worsening of the respiratory picture, the patient was subjected to oro–tracheal intubation and transferred to Intensive Care Unit. The transesophageal echocardiogram (figure) performed in urgency documented: “fistula on the anterior flap of the mitral with medium–severe flow directed from the outflow tract of the left ventricle to the posterolateral wall of the left atrium.” On the recommendation of the infectious disease consultant, intravenous antibiotic therapy with Vancomycin and Gentamicin was started. In the following days, there was a progressive improvement in hemodynamics and the respiratory picture, for which the patient was transferred to Cardiac Surgery to undergo mitral valve replacement surgery. In literature, patients with perivalvular extension of infective endocarditis show very high early and late mortality rates, and surgery during hospitalization for IE appeared to be associated with better outcomes.