The following are key points to remember from this state-of-the-art review on best practices for imaging cardiac device–related infections and endocarditis:

1. Echocardiography is regarded as the first-line imaging modality for patients with suspected prosthetic valve endocarditis (PVE) or cardiac implantable electronic device (CIED)–related infection, as it is widely available, rapid, comprehensive, and relatively inexpensive. This modality can identify structural abnormalities, such as vegetations and abscesses, and functional consequences, such as valvular regurgitation or stenosis, fistulas, and secondary pulmonary hypertension. Though transthoracic echocardiography (TTE) is often performed first because it is noninvasive and safe, transesophageal echocardiography (TEE) is usually required for patients with prosthetic devices or CIEDs when clinical suspicion for endocarditis exists.
2. TEE has a sensitivity of 90% or higher for prosthetic valve vegetations, abscesses, and device lead infections. Entities that may be difficult to identify on TEE include anterior prosthetic ring abscesses and vegetations on distal portions of right ventricular leads.
3. False-negative TEE interpretations may occur in the setting of early abscesses (which may appear hyperechoic rather than hypoechoic), mechanical valves (which can make small vegetations difficult to see), and recent valve surgery (when postoperative changes can be difficult to differentiate from abscess). Conversely, false-positive TEE interpretations may occur when noninfectious thrombi, fibrin strands, or pannus are mistaken for vegetations. Echodensities on CIED leads can be seen in up to 14% of TEEs done for reasons other than suspected endocarditis, and most of these are not infectious.
4. Cardiac computed tomography (CT) can provide information that is complementary to echocardiography in specific scenarios. In patients with prosthetic valves, CT can detect periannular complications such as abscess and can assess precise anatomic relations to other structures, such as the coronary arteries. The role of CT in evaluating CIED infections is limited, in part because of metal artifacts. However, CT can be useful for identifying left ventricular assist device (LVAD) driveline infections and larger abscesses around LVAD components. CT must be protocolled to address the specific clinical scenario, with appropriate contrast timing, gated acquisitions, and use of image reconstruction algorithms.
5. Because immune cell migration occurs early in infectious processes, ¹⁸F-fluoro-2-deoxyglucose positron emission tomography with CT (FDG-PET/CT) is highly sensitive for early cardiac device infection. In the setting of nonspecific morphologic changes on TEE or CT, such as wall thickening, FDG-PET/CT can confirm or refute a diagnosis of endocarditis.
6. For CIED infection, a meta-analysis showed that FDG-PET/CT had pooled sensitivity and specificity of 87% and 94%, respectively. For PVE, sensitivity and specificity were 73-100% and 71-100%, respectively. Based on a recent systematic review, FDG-PET/CT has high sensitivity but variable specificity for LVAD infection. Adding FDG-PET/CT to the modified Duke criteria increases the diagnostic sensitivity from 52-70% to 91-97% without compromising specificity. Thus, FDG-PET/CT may be useful in reclassifying possible endocarditis to definite endocarditis.
7. FDG-PET/CT, as a whole-body scan, is useful for identifying extracardiac infectious emboli.
8. Differentiating infection from inflammation can be challenging, depending upon the clinical scenario. Generally, FDG uptake is focal at an infection site and homogenous in an inflammatory area. The bacteria-specific PET radiotracer ¹⁸F-fluoro-maltohexose appears promising in an experimental model, but clinical data are needed to determine its usefulness in real-world settings.
9. Prior to FDG-PET/CT, meticulous patient preparation is essential to obtain high-quality diagnostic images. A high-fat, low-carbohydrate diet facilitates myocardial fatty acid use and decreases glucose uptake. Though dietary protocols are not well-standardized, for an early morning scan, the panel recommends a high-fat, low-carbohydrate diet starting the evening prior to the scan (or earlier), followed by an overnight fast.

Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Diabetes and Cardiometabolic Disease, Dyslipidemia, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Pulmonary Hypertension and Venous Thromboembolism, Valvular Heart Disease, Vascular Medicine, Implantable Devices, SCD/Ventricular Arrhythmias, Cardiac Surgery and Arrhythmias, Cardiac Surgery and Heart Failure, Cardiac Surgery and VHD, Lipid Metabolism, Mechanical Circulatory Support, Pulmonary Hypertension, Interventions and Imaging, Interventions and Structural Heart Disease, Interventions and Vascular Medicine, Computed Tomography, Echocardiography/Ultrasound, Nuclear Imaging, Diet, Hypertension

Keywords: Abscess, Defibrillators, Implantable, Diagnostic Imaging, Diet, Carbohydrate-Restricted, Echocardiography, Transesophageal, Endocarditis, Endocarditis, Bacterial, Fatty Acids, Fluorodeoxyglucose F18, Heart Valve Diseases, Heart Valve Prosthesis, Heart-Assist Devices, Hypertension, Pulmonary, Image Processing, Computer-Assisted, Positron Emission Tomography Computed Tomography, Whole Body Imaging

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