Role of PET to identify Cardiac implantable electronic device (CIED) infection and infective endocarditis

Objectives: Cardiac implantable electronic devices (CIED) involves Pacemakers, Implantable cardioverter defibrillators, cardiac resynchronization therapy (CRT) devices. With the advances in technology these has been an increase in the utilization of these devices. Infection is an extremely serious complication requiring removal of the infected device. They have an enormous impact on mortality, length of stay and financial burden to the health care system. CIED infections can occur by two pathways, direct contamination of the devices or by hematogenous seeding of the device from a distant source. The pathogens form a biofilm along the devices, making it very difficult to eradicate with antibiotics and necessitates device removal. Echocardiography (ECHO) is the initial diagnostic modality that is used, but its value is less when there is no vegetation seen along the device leads. Hence, newer imaging techniques like FDG-PET/CT can play a role in diagnosis of CIED infections and infective endocarditis. A positive blood culture alone is insufficient to warrant medical intervention when the remaining workup including echocardiogram is negative. In such scenarios, PET/CT may prove useful in identifying device infections that were previously not found on ECHO and prevent unnecessary removal of the devices. FDG-PET/CT should be strongly considered when there is a negative work up but strong clinical suspicion or have no other alternative diagnosis. It is important to consider PET scan in high risk patients with severe sepsis as it is crucial to find the source of infection and prompt removal can lead to improved morbidity and mortality. There have been studies which have shown a good correlation with positive PET/CT findings and clinical/microbiologic findings. FDG-PET/CT can play a crucial role in early diagnosis of such infections to assess patients who require device extraction from those who need to be managed with antibiotics. Diagnostic accuracy of the test is dependent on proper cardiac preparation and appropriate use of antibiotics prior to the imaging procedure as bacterium from the septic foci may utilise the FDG. It can also identify septic emboli to distant sources that are often difficult to identify, such as spondylodiscitis that resulted from bacterial seeding in such patients. Early utilisation of FDG-PET/CT is important as it may help guide management on length of antibiotic therapy or the need for device extraction. In this educational exhibit, we will review the following: 1. Role of PET in CIED infections and IE 2. Role of PET in detection of distant septic emboli 3. Early utilization of PET in high risk groups 4. Future utility of PET in infections 5. Role of PET in guiding management of IE