Infective Endocarditis With Negative Cardiac Multimodal Imaging: A Case Report

Multimodal imaging is a key part of infective endocarditis (IE) diagnostic guidelines. However, we present a case of confirmed IE where evidence of disease was absent on multiple imaging modalities. A patient was admitted following multi-territory ischemic strokes. He had had an aortic root graft with tissue aortic valve replacement and a previous ischemic stroke. During admission, the patient developed pyrexia of unknown origin. Four blood cultures were positive for Staphylococcus haemolyticus. Transthoracic and transoesophageal echocardiogram, as well as ¹⁸F-FDG positron emission tomography/computed tomography (FDG PET/CT) failed to show any signs of IE. However, there was sufficient evidence to diagnose definite endocarditis according to the Modified Duke Criteria. This case report highlights the limitations of imaging in IE diagnosis. Further research into the sensitivity of FDG PET/CT as a diagnostic tool for IE needs to be conducted. This is important to avoid underdiagnosis of IE due to overreliance on radiological evidence.