Abstract
The usefulness of 18F-FDG PET/CT in the diagnosis of infective endocarditis (IE) associated with cardiac implantable electronic devices (CIED) is not well established.
To assess the diagnostic yield of 18F-FDG PET/CT in patients with suspected CIED infections, placing special emphasis on differentiating between pocket infection (PI) and CIED-IE.
From 2013 to 2018, all patients (n=63) admitted to a tertiary care hospital with suspected CIED infection were prospectively recruited, undergoing a thorough diagnostic work-up that included blood cultures extraction, transthoracic (TTE) and transoesophageal echocardiography (TEE) and a PET/CT. When device explantation was required, material from the pocket, generator and leads were also cultured. The gold standard for the diagnosis of CIED-IE was a positive lead culture in the absence of PI when percutaneous extraction was performed or a positive culture from a surgically removed lead. In spite of negative lead cultures, the presence of typical TEE images of vegetations in a clinical context of positive blood cultures was also considered as CIED-IE.
After the whole diagnostic process, 14 (22.2%) cases corresponded to isolated PI and 13 (20.6%) were categorized as CIED-IE. Considering radionuclide uptake in the intracardiac portion of the lead, values of sensitivity, specificity and global diagnostic accuracy of PET/CT for CIED-IE were 38.5%, 98.0% and 85.7%, respectively. Positive and negative likelihood ratio values, 19.2 and 0.6 respectively, suggest that a positive PET/CT is much more probable to correspond to a patient with CIED-IE, whereas it is not possible to exclude this diagnosis in case of a negative result. In the case of PI, fair sensitivity (72.2%) and good specificity values (95.6%) were obtained. Extracardiac lead SUVmax and SUVratio in PI were good, with an area under the ROC curve (AUC) of 0.870 and 0.879, respectively. However, semiquantitative analysis was not useful for the diagnosis of CIED-IE.
In patients with suspected CIED infection, the yield of 18F-FDG PET/CT differs depending on the site of infection, showing a very high specificity but poor sensitivity in CIED-IE; so negative studies must be interpreted with caution if the suspicion of CIED-IE is high.
ROC curves SUVmax and SUV ratio for PI
Type of funding source: None
