Positron emission tomography/computed tomography for diagnosis of prosthetic valve endocarditis: increased valvular 18F-fluorodeoxyglucose uptake as a novel major criterion

Contemporary Role of Positron Emission Tomography (PET) in Endocarditis: A Narrative Review

Endocarditis, a serious infectious disease, remains a diagnostic challenge in contemporary clinical practice. The advent of advanced imaging modalities has contributed significantly to the improved understanding and management of this complex disease. 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) imaging has shown remarkable potential in improving the diagnostic accuracy of endocarditis. In the update of the Modified Duke Criteria, in 2023, The International Society for Cardiovascular Infectious Diseases (ISCVID) Working Group recognized specific 18F-FDG PET/CT findings as a major diagnostic criterion, particularly in patient with prosthetic valve endocarditis. The ability of PET to visualize metabolic activity allows for the identification of infective foci and could differentiate between infective and non-infective processes. This review examines the clinical utility of PET in differentiating infective endocarditis from other cardiovascular pathologies, highlighting its sensitivity and specificity in detecting native and prosthetic valve infections, including patients with transcatheter aortic valve implantation (TAVI), cardiac implantable devices (CIEDs), and left ventricular assistance devices (LVAD). Also, practical aspects and indications are illustrated to optimize the quality of imaging and reduce potential false positive results. In conclusion, the current use of PET in endocarditis has become a valuable diagnostic tool; as technological advances continue, PET will play an increasingly important role in the multidisciplinary approach to the management of endocarditis.

Infection of Transcatheter Valvular Devices

PURPOSE OF REVIEW

This review explores the epidemiology, clinical traits, and diagnosis of Transcatheter Aortic Valve Replacement-Associated Infective Endocarditis (TAVR-IE) and mitral transcatheter edge-to-edge repair infective endocarditis (TEER-IE), focusing on a multimodal imaging approach. It addresses the rising prevalence of TAVR and TEER, emphasizing the need to understand long-term complications and clinical consequences, which poses significant challenges despite advancements in valve technology.

RECENT FINDINGS

Studies report a variable incidence of TAVR-IE and TEER-IE influenced by diverse patient risk profiles and procedural factors. Younger age, male gender, and certain comorbidities emerge as patient-related risk factors. Procedure-related factors include intervention location, valve type, and technical aspects. Microbiologically, Staphylococcus aureus, Viridans Group Streptococcus, and Enterococcus are frequently encountered pathogens. TAVR-IE and TEER-IE diagnosis involves a multimodal imaging approach due to limitations in echocardiography. Blood cultures and imaging aid identification, with Fluorescence in situ hybridization is showing promise. Treatment encompasses medical management with antibiotics and, when necessary, surgical intervention. The management approach requires a multidisciplinary "Endocarditis Team." This review underscores the need for continued research to refine risk prediction, enhance diagnostic accuracy, and optimize management strategies for TAVR-IE, considering the evolving landscape of transcatheter interventions.

Role of multimodality imaging in infective endocarditis: A comparison of the major society guidelines in the United States and Europe

Infective endocarditis (IE) is a life-threatening condition, and early diagnosis and management are critical. There is emerging evidence on the role of advanced imaging modalities including dedicated cardiac computed tomography (CCT), and 18F-fluorodeoxyglucose positron emission tomography (PET). The updated 2023 European Society of Cardiology (ESC) guidelines have emphasized increased utilization of multimodality imaging in the diagnosis and management of IE. In this review, we elaborate on recent recommendations from the updated 2023 ESC guidelines, with comparisons to the current American College of Cardiology (ACC)/American Heart Association (AHA) guidelines, focusing on multimodality imaging in IE.

Dual-Time-Point 18F-FDG PET/CT in Infective Endocarditis: Impact of Delayed Imaging in the Definitive Diagnosis of Endocarditis

Infective endocarditis (IE) is a major public health condition due to the associated high morbidity and mortality. Our objective was to evaluate the utility of dual-time 2-deoxy-2-[18F] fluoro-D-glucose (18F-FDG) Positron Emission Tomography/Computed Tomography (PET/CT) imaging in the diagnosis of active IE in patients with suspected native valve endocarditis (NVE) and prosthetic valve endocarditis (PVE). For this purpose, a retrospective study was carried out, including patients suspicious of NVE or PVE who underwent a dual-time-point 18F-FDG PET/CT. A final diagnosis was established by the Endocarditis Team after patient follow-up using all the available findings. Sixty-nine patients were assessed. A final diagnosis of NVE was established in 3 patients of the 34 by 18F-FDG PET/CT and in the case of PVE was established in 20 patients of the 35. A statistically significant association was found when evaluating the association between PET diagnosis at early acquisition and final diagnosis of IE (χ2 = 30.198, p < 0.001) and PET diagnosis at delayed acquisition for final diagnosis of IE (χ2 = 9.412, p = 0.002). Delayed PET/CT imaging determined the IE diagnosis in 16/58 of the studies. In conclusion, delayed 18F-FDG PET/CT imaging seems to be useful in improving the definitive diagnosis of IE.

PET-scan in diagnosis of non-bacterial thrombotic endocarditis: a case report

BACKGROUND

Non-bacterial thrombotic endocarditis (NBTE), also known as marantic endocarditis or Libman-Sacks endocarditis, is a rare non-infectious condition affecting mostly the left-sided heart valves of patients who, most often, suffer from malignancies and connective tissue disorders. Herein, we present a case of a male patient with marantic endocarditis due to occult lung adenocarcinoma.

CASE PRESENTATION

The patient fulfilled the modified Duke's criteria of possible bacterial endocarditis of the aortic valve; however, multiple blood cultures and serological tests were negative. In addition, the patient's clinical course was constantly deteriorating. Thus, a fluorodeoxyglucose-positron emission tomography (FDG-PET) scan was conducted. This examination revealed multiple positive thoracic lymph node groups, as well as a positive lung lesion. The patient underwent aortic valve replacement and lymph biopsies during the operation established the diagnosis of solid/micropapillary lung adenocarcinoma and consequently of the non-bacterial thrombotic endocarditis.

CONCLUSIONS

Advanced imaging techniques may be needed to diagnose NBTE and should be kept in mind when the Duke criteria are not definite. Clinical suspicion is key to implement these premises. However, the exact role of the PET-scan has yet to be specified.

Novel Diagnostic Methods for Infective Endocarditis

Infective endocarditis (IE) remains a dangerous disease and continues to have a high mortality rate. Unfortunately, despite continuous improvements in diagnostic methods, in many cases, blood cultures remain negative, and the pathogen causing endocarditis is unknown. This makes targeted therapy and the selection of appropriate antibiotics impossible. Therefore, we present what methods can be used to identify the pathogen in infective endocarditis. These are mainly molecular methods, including PCR and MGS, as well as imaging methods using radiotracers, which offer more possibilities for diagnosing IE. However, they are still not widely used in the diagnosis of IE. The article summarizes in which cases we should choose them and what we are most hopeful about in further research into the diagnosis of IE. In addition, registered clinical trials that are currently underway for the diagnosis of IE are also presented.

The Role of the 18F-FDG PET/CT in the Management of Patients Suspected of Cardiac Implantable Electronic Devices' Infection

Background: Infection of Cardiac Implantable Electronic Devices (CIEDI) is a real public health problem. The main aim of this study was to determine the diagnostic performance of 18F-FDG PET/CT in the diagnosis of CIEDI. Methods: A total of 48 patients, who performed 18F-FDG PET/CT for the clinical suspicion of CIEDI were retrospectively analyzed; all patients were provided with a model with procedural recommendations before the exam. Sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy (DA) of 18F-FDG PET/CT were calculated; the reproducibility of qualitative analysis was assessed with Cohen's κ test. The semi-quantitative parameters (SUVmax, SQR and TBR) were evaluated in CIEDI+ and CIEDI- patients using the Student' t-test; ROC curves were elaborated to detect cut-off values. The trend of image quality with regards to procedural recommendation adherence was evaluated. Results: Se, Sp, PPV, NPV and DA were respectively 96.2%, 81.8%, 86.2%, 94.7% and 89.6%. The reproducibility of qualitative analysis was excellent (K = 0.89). Semiquantitative parameters resulted statistically different in CIEDI+ and CIEDI- patients. Cut-off values were SUVmax = 2.625, SQR = 3.766 and TBR = 1.29. Trend curves showed increasing image quality due to adherence to procedural recommendations. Conclusions:18F-FDG-PET/CT is a valid tool in the management of patients suspected of CIEDI and adherence to procedural recommendations improves its image quality.

Current status and perspectives of nuclear cardiology

Nuclear cardiology has long been used to identify myocardial ischemia for appropriate treatment strategies for stable coronary artery disease (CAD). After the Ischemia Trial, it is time to reevaluate the significance of ischemia assessment. Functional imaging continues to play pivotal role in detecting microcirculatory disturbances. PET provides a clear image of blood flow distribution and is useful for the quantitative evaluation of myocardial flow reserve (MFR), which plays an important role in predicting treatment strategies and improving prognosis in CAD. Heart failure has become a major area of focus in cardiovascular medicine. Radionuclide imaging has been widely applied in this field. FDG PET is useful in identifying cardiac sarcoidosis and active inflammation. Clinical values of I-123 MIBG and BMIPP SPECT have been reported worldwide from Japan. Additionally, clinical experiences of Tc-99m pyrophosphate imaging have recently gained attention for assessing cardiac amyloidosis. Cardiac PET/CT and PET/MR imaging permit combined assessment of metabolic/functional/structural analyses of various cardiac diseases. While other non-invasive imaging modalities have rapidly been developed, the roles of radionuclide imaging remain to be valuable for early and accurate diagnosis and patient management in most cases of chronic CAD and various cardiovascular diseases.

Multimodality Imaging Diagnosis in Infective Endocarditis

Imaging is an important tool in the diagnosis and management of infective endocarditis (IE). Echocardiography is an essential examination, especially in native valve endocarditis (NVE), but its diagnostic accuracy is reduced in prosthetic valve endocarditis (PVE). The diagnostic ability is superior for transoesophageal echocardiography (TEE), but a negative test cannot exclude PVE. Both transthoracic echocardiography (TTE) and TEE can provide normal or inconclusive findings in up to 30% of cases, especially in patients with prosthetic devices. New advanced non-invasive imaging tests are increasingly used in the diagnosis of IE. Nuclear medicine imaging techniques have demonstrated their superiority over TEE for the diagnosis of PVE and cardiac implantable electronic device infective endocarditis (CIED-IE). Cardiac computed tomography angiography imaging is useful in PVE cases with inconclusive TTE and TEE investigations and for the evaluation of paravalvular complications. In the present review, imaging tools are described with their values and limitations for improving diagnosis in NVE, PVE and CIED-IE. Current knowledge about multimodality imaging approaches in IE and imaging methods to assess the local and distant complications of IE is also reviewed. Furthermore, a potential diagnostic work-up for different clinical scenarios is described. However, further studies are essential for refining diagnostic and management approaches in infective endocarditis, addressing limitations and optimizing advanced imaging techniques across different clinical scenarios.

The Role of Multimodality Imaging in Patients with Congenital Heart Disease and Infective Endocarditis

Infective endocarditis (IE) represents an important medical challenge, particularly in patients with congenital heart diseases (CHD). Its early and accurate diagnosis is crucial for effective management to improve patient outcomes. Multimodality imaging is emerging as a powerful tool in the diagnosis and management of IE in CHD patients, offering a comprehensive and integrated approach that enhances diagnostic accuracy and guides therapeutic strategies. This review illustrates the utilities of each single multimodality imaging, including transthoracic and transoesophageal echocardiography, cardiac computed tomography (CCT), cardiovascular magnetic resonance imaging (CMR), and nuclear imaging modalities, in the diagnosis of IE in CHD patients. These imaging techniques provide crucial information about valvular and intracardiac structures, vegetation size and location, abscess formation, and associated complications, helping clinicians make timely and informed decisions. However, each one does have limitations that influence its applicability.

Prognosis and follow-up of patients with prosthetic valve endocarditis treated conservatively in relation to WBC-SPECT imaging

BACKGROUND

Our objective was to evaluate in patients with prosthetic valve endocarditis (PVE) treated conservatively, the prognostic value of white blood cell (WBC) signal intensity on SPECT and to describe the evolution of the WBC signal under antibiotics.

METHODS

Patients with PVE treated conservatively and positive WBC-SPECT imaging were identified retrospectively. Signal intensity was classified as intense if equal to or higher, or mild if lower, than the liver signal. Clinical, biological, imaging and follow-up information were collected from medical files.

RESULTS

Among 47 patients, WBC signal was classified as intense in 10 patients and as mild, in 37. The incidence of the primary composite endpoint (death, late cardiac surgery, or relapse) was significantly higher in patients with intense vs. mild signal (90% vs. 11%). Twenty-five patients underwent a second WBC-SPECT imaging during follow-up. The prevalence of WBC signal decreased progressively from 89% between 3 and 6 weeks to 42% between 6 and 9 weeks and 8% more than 9 weeks after initiation of antibiotics.

CONCLUSIONS

In patients with PVE treated conservatively, intense WBC signal was associated with poor outcome. WBC-SPECT imaging appears as an interesting tool for risk stratification and to monitor locally the efficacy of antibiotic treatment.

Role of molecular imaging in the diagnosis of prosthetic aortic valve endocarditis by Bacillus licheniformis: a case report

Background

Infective endocarditis is a challenging diagnosis that usually requires cardiovascular image confirmation as part of the approach. 18F-Fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) is an imaging technique more sensible for the diagnosis of prosthetic valve endocarditis (PVE) when echocardiography is inconclusive.

Case summary

We present the case of a 35-year-old man who had a previous Bentall-De Bono procedure 4 years prior that included biological, national institute of cardiology (INC)-type, locally manufactured aortic valve replacement and woven Dacron tube graft implantation in the ascending aorta. He was admitted because of dyspnoea, oedema, fever, and syncope. A complete auriculoventricular blockade was diagnosed, requiring cardiac pacing. Also, infective endocarditis (IE) was suspected. Blood cultures showed the isolation of Bacillus licheniformis. Transthoracic echocardiography, transoesophageal echocardiography, and CT angiography were inconclusive for IE. Treatment was initiated with intravenous (IV) antibiotic therapy, and an extensive protocol for IE, including molecular imaging modalities, was ordered. 99mTc-Ubiquicidin scintigraphy was acquired without abnormal findings. Images of 18F-FDG-PET/CT revealed abnormally intense heterogeneous uptake in the prosthetic aortic annulus in a classic pattern. Applying the modified 2015 Duke criteria for PET/CT, PVE was confirmed.

Discussion

Although the other imaging modalities were negative, the high clinical suspicion made it mandatory to continue the study protocol, remarking on the utility of 18F-FDG-PET/CT on patients categorized as having 'possible' endocarditis, as in our patient.

Real world experience of therapeutic monitoring of medically treated prosthetic valve infective endocarditis by 18F-FDG-PET/CT

INTRODUCTION

18F-FDG-PET/CT is recommended to improve the diagnosis of prosthetic valve infective endocarditis (PVIE) and is a major criterion in the ESC-2015 classification. However, there is little evidence for its usefulness in the follow-up of medically treated PVIE patients.

METHODS

A monocentric retrospective analysis of patients hospitalized for PVIE between January 2013 and December 2019 who were not treated with surgery and who had at least two 18F-FDG-PET/CT examinations during their medical management.

RESULTS

Among 170 patients with PVIE, 117 were treated with antibiotic therapy but no surgery. Of these, 36 (31%) had at least two 18F-FDG-PET/CT examinations. At initial imaging, 28 patients had heterogeneous FDG uptake on their prosthetic valve and eight on their associated aortic graft. Hypermetabolism of spleen and bone marrow (HSBM) was observed in 18 and 19 patients, respectively. At the first follow-up 18F-FDG-PET/CT, 21 (58%) patients still had heterogeneous uptake, indicating persistent active endocarditis. HSBM was still present at the last follow-up imaging in four of the six patients with recurrent PVIE.

CONCLUSION

18F-FDG-PET/CT monitoring of medically treated patients with PVIE provides valuable additional information and prospective multicentric study should be conducted to assess its usefulness.

Contemporary Features and Management of Endocarditis

Infective endocarditis is a rare but devastating disease. Morbidity and mortality rates have failed to improve despite new technological advances. The disease has evolved over time with new significant populations at risk-most notably those with prosthetic valves or implantable cardiovascular devices. These devices pose new challenges for achieving a timely and accurate diagnosis of infection. While the modified Duke criteria is accepted as the gold standard for diagnosing native valve endocarditis, it has been shown to have significantly inferior sensitivity when it comes to identifying infections related to right-heart endocarditis, prosthetic valves, and indwelling cardiac devices. Additionally, prosthetic valves and cardiovascular implantable electronic devices can exhibit shadowing and artifact, rendering transthoracic echocardiography and transesophageal echocardiography results inconclusive or even normal. Having a keen awareness of the varying clinical presentations, as well as emerging valvular imaging modalities such as F-fluorodeoxyglucose cardiac positron-emission tomography plus computed tomography, promises to improve the evaluation and diagnosis of infective endocarditis. However, indications for appropriate use of these studies and guidance on modern clinical management are still needed.

Meta-analysis assessing the sensitivity and specificity of 18F-FDG PET/CT for the diagnosis of prosthetic valve endocarditis (PVE) using individual patient data (IPD)

IMPORTANCE

The use of ¹⁸F-FDG PET/CT in diagnostic algorithms for PVE has increased since publication of studies and guidelines advocating its use. The assessment of test accuracy has been limited by small study sizes. We undertook a systematic review using individual patient data (IPD) meta-analysis techniques.

OBJECTIVE

To estimate the summary sensitivity and specificity of ¹⁸F-FDG PET/CT in diagnosing PVE. We also assessed the effect of patient factors on test accuracy as defined by changes in the odds ratios associated with each factor. The effect of the PET/CT study on the final diagnosis was also assessed when compared to the preliminary Duke classification to determine in which patient group ¹⁸F-FDG PET/CT had the greatest utility.

STUDY SELECTION

Studies were included if PET/CT was performed for suspicion of PVE and IPD of both the PET/CT result and final diagnosis defined by a gold-standard assessment was available. There were 3 possible final diagnoses ("definite PVE," "possible PVE," and "rejected PVE").

RESULTS

Seventeen studies were included with IPD available for 537 patients (from 538 scans). The summary sensitivity and specificity were 85% (95% CI 74.2%-91.8%) and 86.5% (95% CI 75.8%-92.9%) respectively when patients with final diagnosis of "possible PVE" were classified as positive for PVE. When this group was classified as negative for PVE, sensitivity was 87.4% (95% CI 80.4%-92.1%) and specificity was 84.9% (95% CI 71.5%-92.6%). Patients with a known pathogen (especially coagulase negative staphylococcal species), elevated CRP, a biological or aortic valve infection appeared more likely to have an accurate PET/CT diagnosis. Those with a mechanical valve, prior antibiotic treatment or a transcatheter aortic valve replacement valve were less likely to have an accurate test. Time since valve implantation and the presence of surgical adhesive did not appear to affect test accuracy. Of the patients with a preliminary Duke classification of "possible PVE," 84% received a more conclusive final diagnosis of "definite" or "rejected" PVE after the PET/CT study.

CONCLUSIONS AND RELEVANCE

¹⁸F-FDG PET/CT has high sensitivity and specificity in diagnosing PVE and the diagnostic utility is greatest in patients with a preliminary Duke classification of "possible PVE." Some patient factors appear to affect test accuracy, though these results should be interpreted with caution given low patient numbers for subgroup analyses.

Contemporary management of infective endocarditis in pregnancy

INTRODUCTION

Infective endocarditis (IE) during pregnancy is a rare condition that is associated with a high level of morbidity and mortality. The epidemiology, diagnosis, treatment, and prognosis have changed significantly in the last two decades. The declining incidence of rheumatic heart disease, improved life expectancy with congenital heart disease, advances in cardiac surgery and cardiac devices, rise in resistant microorganisms, complications of the opioid epidemic, and increasing maternal age are some of the many factors contributing to these changes.

AREAS COVERED

This article explores existing literature on the topic including case reports, case series, registry data, and clinical guidelines. The focus of this article is the evolving epidemiology, predisposing factors and preventative measures, clinical presentation, investigation, management, and potential complications of IE in pregnancy.

EXPERT OPINION

Robust prospective data on the management of IE in pregnancy is lacking, and obtaining these data will be very challenging. It is imperative that international registries are used to provide data on best clinical practices and inform future clinical guidelines. Multimodal imaging should be incorporated in the investigation of complicated cases. A multidisciplinary approach to the management of this rare and life-threatening condition is essential to ensure the best outcomes for both the mother and the fetus.

Utility of Intracardiac Echocardiography for Infective Endocarditis and Cardiovascular Device-Related Endocarditis: A Contemporary Systematic Review

The diagnosis of infective endocarditis (IE) can pose a significant challenge, particularly in cases of prosthetic valve endocarditis (PVE) or cardiac device-related endocarditis (CDIE) (1). While echocardiography remains a crucial diagnostic tool for identifying IE, including PVE and CDIE, there are certain circumstances where transesophageal echocardiography (TEE) may not be conclusive or practically feasible (2). Recently, intracardiac echocardiography (ICE) has emerged as a promising alternative for diagnosing IE and evaluating intracardiac infections, especially in cases where transthoracic echocardiography (TTE) has not been revealing, and TEE has been contraindicated. Furthermore, ICE has been found to be useful in guiding transvenous lead extractions in infected implantable cardiac devices (3). This systematic review aims to comprehensively explore the various applications of ICE in the diagnosis of IE and assess its efficacy in comparison to traditional diagnostic methods.

Hot spot imaging in cardiovascular diseases: an information statement from SNMMI, ASNC, and EANM

This information statement from the Society of Nuclear Medicine and Molecular Imaging, American Society of Nuclear Cardiology, and European Association of Nuclear Medicine describes the performance, interpretation, and reporting of hot spot imaging in nuclear cardiology. The field of nuclear cardiology has historically focused on cold spot imaging for the interpretation of myocardial ischemia and infarction. Hot spot imaging has been an important part of nuclear medicine, particularly for oncology or infection indications, and the use of hot spot imaging in nuclear cardiology continues to expand. This document focuses on image acquisition and processing, methods of quantification, indications, protocols, and reporting of hot spot imaging. Indications discussed include myocardial viability, myocardial inflammation, device or valve infection, large vessel vasculitis, valve calcification and vulnerable plaques, and cardiac amyloidosis. This document contextualizes the foundations of image quantification and highlights reporting in each indication for the cardiac nuclear imager.

Utility of nuclear cardiovascular imaging in the cardiac intensive care unit

The contemporary Cardiac Intensive Care Unit (CICU) has evolved into a complex unit that admits a heterogeneous mix of patients with a wide range of acute cardiovascular diseases often complicated by multi-organ failure. Although electrocardiography (ECG) and echocardiography are well-established as first-line diagnostic modalities for assessing patients in the CICU, nuclear cardiology imaging has emerged as a useful adjunctive diagnostic modality. The versatility, safety and accuracy of nuclear imaging (e.g., perfusion, metabolism, inflammation) for the assessment of patient with coronary artery disease, ventricular arrhythmias, infiltrative cardiomyopathies, infective endocarditis and inflammatory aortopathies has been proven useful and now often incorporated into the best practices for the management of critically ill cardiac patients. Thus, clinicians must familiarize themselves with the value and current and future applications of nuclear imaging in the management of the cardiac patient in the CICU.

18F-FDG-Based Radiomics and Machine Learning: Useful Help for Aortic Prosthetic Valve Infective Endocarditis Diagnosis?

BACKGROUND

Fluorine-18 fluorodeoxyglucose (¹⁸F-FDG)-positron emission tomography (PET)/computed tomography (CT) results in better sensitivity for prosthetic valve endocarditis (PVE) diagnosis, but visual image analysis results in relatively weak specificity and significant interobserver variability.

OBJECTIVES

The primary objective of this study was to evaluate the performance of a radiomics and machine learning-based analysis of ¹⁸F-FDG PET/CT (PET-ML) as a major criterion for the European Society of Cardiology score using machine learning as a major imaging criterion (ESC-ML) in PVE diagnosis. The secondary objective was to assess performance of PET-ML as a standalone examination.

METHODS

All ¹⁸F-FDG-PET/CT scans performed for suspected aortic PVE at a single center from 2015 to 2021 were retrospectively included. The gold standard was expert consensus after at least 3 months' follow-up. The machine learning (ML) method consisted of manually segmenting each prosthetic valve, extracting 31 radiomics features from the segmented region, and training a ridge logistic regressor to predict PVE. Training and hyperparameter tuning were done with a cross-validation approach, followed by an evaluation on an independent test database.

RESULTS

A total of 108 patients were included, regardless of myocardial uptake, and were divided into training (n = 68) and test (n = 40) cohorts. Considering the latter, PET-ML findings were positive for 13 of 22 definite PVE cases and 3 of 18 rejected PVE cases (59% sensitivity, 83% specificity), thus leading to an ESC-ML sensitivity of 72% and a specificity of 83%.

CONCLUSIONS

The use of ML for analyzing ¹⁸F-FDG-PET/CT images in PVE diagnosis was feasible and beneficial, particularly when ML was included in the ESC 2015 criteria. Despite some limitations and the need for future developments, this approach seems promising to optimize the role of ¹⁸F-FDG PET/CT in PVE diagnosis.

Radionuclide Imaging of Infective Endocarditis

Infective endocarditis (IE) is associated with high morbidity and mortality. Early diagnosis is crucial for adequate patient management. Due to difficulties in the diagnosis, a multidisciplinary discussion in addition to the integration of clinical signs, microbiology data, and imaging data is used. Imaging, including echocardiography, molecular imaging techniques, and coronary CT angiography (CTA) is central to detect infections involving heart valves and implanted cardiovascular devices, also allowing for early detection of septic emboli and metastatic. This article describes the main clinical application of white blood cell SPECT/CT and [¹⁸F]FDG-PET/CT and CTA in IE and infections associated with cardiovascular implantable electronic devices.

Infective Endocarditis After Transcatheter Aortic Valve Implantation: A Systematic Review

Infective endocarditis (IE) after transcatheter aortic valve implantation (TAVI) is a rare but potentially fatal event. In this systematic review, we searched PubMed and Embase for large TAVI studies and registries to identify the incidence, presentation, microbiology, risk factors, and outcomes of IE in this population. After application of the selection criteria and quality assessment, 8 studies representing 255,310 TAVR cases and 4218 cases of IE qualified for this review. IE following TAVI is uncommon with an incidence of 0.87 to 1.7 events per 100 person-years. Most events occur in the first year following valve implantation. Staphylococcus , Enterococcus , and Streptococcus species are the most common pathogens. Risk factors include age, sex, concomitant comorbidities, and procedural factors. Outcomes are dismal, and surgical intervention is rare in this population.

Imaging of Endocarditis and Cardiac Device-Related Infections: An Update

IE is a deadly disease requiring prompt diagnosis for adequate patient's management. The diagnosis requires the integration of clinical signs, microbiology data and imaging data and proper discussion within a multidisciplinary team, the endocarditis team. Since the introduction of ¹⁸F-FDG-PET/CT and WBC SPECT/CT in the diagnostic algorithm of PVE the nuclear medicine imaging specialists is active part of the Endocarditis Team, requiring proper knowledge of dedicated imaging acquisition protocols, expertise for imaging reading and interpretations to select the best test or combination of tests for each specific clinical situation. In this manuscript, we will review the main technical aspects of each imaging procedure, the most recent literature with specific regards to special challenging populations and provide clinical examples.

Risk factors for Gram-negative bacterial infection of cardiovascular implantable electronic devices: multicentre observational study (CarDINe Study)

BACKGROUND

Infections of cardiovascular implantable electronic devices (CIED) are mainly due to Gram-positive bacteria (GPB). Data about Gram-negative bacteria CIED (GNB-CIED) infections are limited. This study aimed to investigate risk factors, clinical and diagnostic characteristics, and outcome of patients with GNB-CIED.

METHODS

A multicentre, international, retrospective, case-control-control study was performed on patients undergoing CIED implantation from 2015 to 2019 in 17 centres across Europe. For each patient diagnosed with GNB-CIED, one matching control with GPB-CIED infection and two matching controls without infection were selected.

RESULTS

A total of 236 patients were enrolled: 59 with GNB-CIED infection, 59 with GPB-CIED infection and 118 without infection. No between-group differences were found regarding clinical presentation, diagnostic and therapeutic management. A trend toward a higher rate of fluorodeoxyglucose positron emission computed tomography (FDG PET/CT) positivity was observed among patients with GNB than in those with GPB-CIED infection (85.7% vs. 66.7%; P = 0.208). Risk factors for GNB-CIED infection were Charlson Comorbidity Index Score (relative risk reduction, RRR = 1.211; P = 0.011), obesity (RRR = 5.122; P = 0.008), ventricular-pacing ventricular-sensing inhibited-response pacemaker implantation (RRR = 3.027; P = 0.006) and right subclavian vein site of implantation (RRR = 5.014; P = 0.004). At 180-day survival analysis, GNB-CIED infection was associated with increased mortality risk (HR = 1.842; P = 0.067).

CONCLUSIONS

Obesity, high number of comorbidities and right subclavian vein implantation site were associated with increased risk of GNB-CIED infection. A prompt therapeutic intervention that may be guided using FDG PET/CT is suggested in patients with GNB-CIED infection, considering the poorer outcome observed in this group.

PET/MR imaging of inflammation in atherosclerosis

Myocardial infarction, stroke, mental disorders, neurodegenerative processes, autoimmune diseases, cancer and the human immunodeficiency virus impact the haematopoietic system, which through immunity and inflammation may aggravate pre-existing atherosclerosis. The interplay between the haematopoietic system and its modulation of atherosclerosis has been studied by imaging the cardiovascular system and the activation of haematopoietic organs via scanners integrating positron emission tomography and resonance imaging (PET/MRI). In this Perspective, we review the applicability of integrated whole-body PET/MRI for the study of immune-mediated phenomena associated with haematopoietic activity and cardiovascular disease, and discuss the translational opportunities and challenges of the technology.

Contemporary Review of Multi-Modality Cardiac Imaging Evaluation of Infective Endocarditis

Infective endocarditis (IE) remains to be a heterogeneous disease with high morbidity and mortality rates, which can affect native valves, prosthetic valves, and intra-cardiac devices, in addition to causing systemic complications. The combination of clinical, laboratory, and cardiac imaging evaluation is critical for early diagnosis and risk stratification of IE. This can facilitate timely medical and surgical management to improve patient outcomes. Key imaging findings for IE include vegetations, valve perforation, prosthetic valve dehiscence, pseudoaneurysms, abscesses, and fistulae. Transthoracic echocardiography continues to be the first-line imaging modality of choice, while transesophageal echocardiography subsequently provides an improved structural assessment and characterization of lesions to facilitate management decision in IE. Recent advances in other imaging modalities, especially cardiac computed tomography and 18F-fluorodeox-yglucose positron emission tomography, and to a lesser extent cardiac magnetic resonance imaging and other nuclear imaging techniques, have demonstrated important roles in providing complementary IE diagnostic and prognostic information. This review aims to discuss the individual and integrated utilities of contemporary multi-modality cardiac imaging for the assessment and treatment guidance of IE.

Advances in Molecular Imaging in Infective Endocarditis

Infective endocarditis (IE) is a growing epidemiological challenge. Appropriate diagnosis remains difficult due to heterogenous etiopathogenesis and clinical presentation. The disease may be followed by increased mortality and numerous diverse complications. Developing molecular imaging modalities may provide additional insights into ongoing infection and support an accurate diagnosis. We present the current evidence for the diagnostic performance and indications for utilization in current guidelines of the hybrid modalities: single photon emission tomography with technetium99m-hexamethylpropyleneamine oxime-labeled autologous leukocytes (^99mTc-HMPAO-SPECT/CT) along with positron emission tomography with fluorodeoxyglucose (¹⁸F-FDG PET/CT). The role of molecular imaging in IE diagnostic work-up has been constantly growing due to technical improvements and the increasing evidence supporting its added diagnostic and prognostic value. The various underlying molecular processes of ^99mTc-HMPAO-SPECT/CT as well as ¹⁸F-FDG PET/CT translate to different imaging properties, which should be considered in clinical practice. Both techniques provide additional diagnostic value in the assessment of patients at risk of IE. Nuclear imaging should be considered in the IE diagnostic algorithm, not only for the insights gained into ongoing infection at a molecular level, but also for the determination of the optimal clinical therapeutic strategies.

Infective Endocarditis after Transcatheter Aortic Valve Replacement: Challenges in the Diagnosis and Management

Although initially conceived for high-risk patients who are ineligible for surgical aortic valve replacement (SAVR), transcatheter aortic valve replacement (TAVR) is now recommended in a wider spectrum of indications, including among young patients. However, similar to SAVR, TAVR is also associated with a risk of infectious complications, namely, prosthetic valve endocarditis (PVE). As the number of performed TAVR procedures increases, and despite the low incidence of PVE post-TAVR, clinicians should be familiar with its associated risk factors and clinical presentation. Whereas the diagnosis of native valve endocarditis can be achieved straightforwardly by applying the modified Duke criteria, the diagnosis of PVE is more challenging given its atypical symptoms, the lower sensitivity of the criteria involved, and the low diagnostic yield of conventional echocardiography. Delay in proper management can be associated with increased morbidity and mortality. Therefore, clinicians should have a high index of suspicion and initiate proper work-up according to the severity of the illness, the underlying host, and the local epidemiology of the causative organisms. The most common causative pathogens are Gram-positive bacteria such as Staphylococcus aureus, coagulase-negative staphylococci, Enterococcus spp., and Streptococcus spp. (particularly the viridans group), while less-likely causative pathogens include Gram-negative and fungal pathogens. The high prevalence of antimicrobial resistance complicates the choice of therapy. There remain controversies regarding the optimal management strategies including indications for surgical interventions. Surgical assessment is recommended early in the course of illness and surgical intervention should be considered in selected patients. As in other PVE, the duration of therapy depends on the isolated pathogen, the host, and the clinical response. Since TAVR is a relatively new procedure, the outcome of TAVR-PVE is yet to be fully understood.

The Emerging Role of FDG PET/CT in Diagnosing Endocarditis and Cardiac Device Infection

Infective endocarditis and cardiac implantable electronic device infection (CIEDI) have witnessed an increasing incidence in clinical practice and associated with increasing health care expenditure. Expanding indications of CIED in various cardiovascular conditions have also contributed to the surge of these infections. Early diagnosis of these infections is associated with a favorable prognosis. Given the lack of a single definitive diagnostic method and the limitations of echocardiography, which is considered a central diagnostic imaging modality, additional imaging modalities are required. Recent studies have highlighted the diagnostic utility of FDG PET and CT. In this review article, we discuss the existing limitations of echocardiography, acquisition protocols of PET/CT, and indications of these advanced imaging modalities in infective endocarditis and CIEDI diagnosis.

To what extent does prior antimicrobial therapy affect the diagnostic performance of radiolabeled leukocyte scintigraphy in infective endocarditis?

AIMS

This prospective, single-center study sought to assess to what extent there is interference between the hybrid technique of single-photon emission tomography-computed tomography with technetium99m-hexamethylpropyleneamine oxime-labeled leukocytes (99mTc-HMPAO-SPECT/CT) and antimicrobial therapy in patients with infective endocarditis (IE).

METHODS AND RESULTS

During the years 2015-2019, we enrolled 205 consecutive adults with suspected IE, all underwent 99mTc-HMPAO-SPECT/CT. The study population was divided into those who had received antimicrobial therapy up to 30 days prior to 99mTc-HMPAO-SPECT/CT (group 1, n = 96) and those who had not (group 2, n = 109). Patients were prospectively observed for 12 ± 10 months. Group 1 presented higher positive predictive values (91.89% vs. 60.00%, = 0.001), and decreased negative predictive values (77.97% vs. 90.54%, P = 0.04). Patients treated with antimicrobial therapy displayed false-negative 99mTc-HMPAO-SPECT/CT results more often [odds ratio (OR), 4.63; 95% confidence interval (CI), 1.41-15.23, P = .01], particularly when intravenous (OR 5.37; 95% CI 1.73-16.62, P = .004), definite (OR 9.43; 95% CI 2.65-33.51, P = .001), and combination antibiotic regimens (OR 8.1; 95% CI 2.57-25.64, P = .001) had been administered.

CONCLUSION

Prior antibiotic therapy affects 99mTc-HMPAO-SPECT/CT diagnostic properties. Patients treated with antimicrobial therapy display false-negative 99mTc-HMPAO-SPECT/CT results more often, especially if intravenous, definite, or combination regimens are administered.

Molecular Imaging of Valvular Diseases and Cardiac Device Infection

The use of positron emission tomography imaging with 18F-fluorodeoxyglucose in the diagnostic workup of patients with suspected prosthetic valve endocarditis and cardiac device infection (implantable electronic device and left ventricular assist device) is gaining momentum in clinical practice. However, in the absence of prospective randomized trials, guideline recommendations about 18F-fluorodeoxyglucose positron emission tomography in this setting are currently largely based on expert opinion. Measurement of aortic valve microcalcification occurring as a healing response to valvular inflammation using 18F-sodium fluoride positron emission tomography represents another promising clinical approach, which is associated with both the risk of native valve stenosis progression and bioprosthetic valve degeneration in research trials. In this review, we consider the role of molecular imaging in cardiac valvular diseases, including aortic stenosis and valvular endocarditis, as well as cardiac device infections.

Infective Endocarditis: Predictive Factors for Diagnosis and Mortality in Surgically Treated Patients

Background: Diagnosis of infective endocarditis (IE) often is challenging, and mortality is high in such patients. Our goal was to characterize common diagnostic tools to enable a rapid and accurate diagnosis and to correlate these tools with mortality outcomes. Methods: Because of the possibility of including perioperative diagnostics, only surgically treated patients with suspected left-sided IE were included in this retrospective, monocentric study. A clinical committee confirmed the diagnosis of IE. Results: 201 consecutive patients (age 64 ± 13 years, 74% male) were finally diagnosed with IE, and 14 patients turned out IE-negative. Preoperative tests with the highest sensitivity for IE were positive blood cultures (89.0%) and transesophageal echocardiography (87.5%). In receiver operating characteristics, vegetation size revealed high predictive power for IE (AUC 0.800, p < 0.001) with an optimal cut-off value of 11.5 mm. Systemic embolism was associated with mortality, and N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) had predictive power for mortality. Conclusion: If diagnostic standard tools remain inconclusive, we suggest employing novel cut-off values to increase diagnostic accuracy and accelerate diagnosis. Patients with embolism or elevated NT-proBNP deserve a closer follow-up.

18F-FDG PET/MRI Imaging in a Preclinical Rat Model of Cardiorenal Syndrome-An Exploratory Study

Cardiorenal syndrome (CRS) denotes the bidirectional interaction of chronic kidney disease and heart failure with an adverse prognosis but with a limited understanding of its pathogenesis. This study correlates biochemical blood markers, histopathological and immunohistochemistry features, and 2-deoxy-2-fluoro-D-glucose positron emission tomography (¹⁸F-FDG PET) metabolic data in low-dose doxorubicin-induced heart failure, cardiorenal syndrome, and renocardiac syndrome induced on Wistar male rats. To our knowledge, this is the first study that investigates the underlying mechanisms for CRS progression in rats using ¹⁸F-FDG PET. Clinical, metabolic cage monitoring, biochemistry, histopathology, and immunohistochemistry combined with PET/MRI (magnetic resonance imaging) data acquisition at distinct points in the disease progression were employed for this study in order to elucidate the available evidence of organ crosstalk between the heart and kidneys. In our CRS model, we found that chronic treatment with low-dose doxorubicin followed by acute 5/6 nephrectomy incurred the highest mortality among the study groups, while the model for renocardiac syndrome resulted in moderate-to-high mortality. ¹⁸F-FDG PET imaging evidenced the doxorubicin cardiotoxicity with vascular alterations, normal kidney development damage, and impaired function. Given the fact that standard clinical markers were insensitive to early renal injury, we believe that the decreasing values of the ¹⁸F-FDG PET-derived renal marker across the groups and, compared with their age-matched controls, along with the uniform distribution seen in healthy developing rats, could have a potential diagnostic and prognostic yield in cardiorenal syndrome.

Value of 18F-FDG pet/CT for prognostic assessment in patients with infective endocarditis

BACKGROUND

¹⁸F-FDG PET/CT is a valuable diagnostic tool in infective endocarditis (IE). However, the prognostic value is unclear. This study aims to evaluate the prognostic performance of ¹⁸F-FDG PET/CT in native valve endocarditis (NVE) and prosthetic valve endocarditis (PVE).

METHODS

We retrospectively included 76 patients treated for definite IE (NVE and PVE) that underwent ¹⁸F-FDG PET/CT between January 2016 and December 2018. Clinical, echocardiographic and ¹⁸F-FDG PET/CT (pathologic valvular ¹⁸F-FDG uptake, extracardiac complications (ECC)) data were collected. The primary endpoint was defined as mortality or recurrence of IE at a one-year follow-up.

RESULTS

Pathologic valvular ¹⁸F-FDG uptake was detected in 32 of 57 (56.1%) patients, 30% (9/30) in NVE and 85.2% (23/27) in PVE group. Atrial fibrillation (OR 3.90, 95% CI = 1.14-16.3), prior anticoagulation treatment (OR 6.37, 95% CI = 1.89-26.7), large vegetation (≥ 10 mm) (OR 4.05, 95% CI = 1.14-16.1), perivalvular complications (OR 7.22, 95% CI = 1.68-55.1) and abscess (OR 10.9, 95% CI = 1.84-283) were associated with positive PET/CT. Extracardiac complications were found in 27 of 76 (35.5%) patients, 42.9% (18/42) in the NVE and 26.5% (9/34) in the PVE group. Pathological valvular tracer uptake (HR 1.20, 95% CI = 0.43-3.37) or extracardiac complications (HR 0.58, 95% CI = 0.21-1.62) were not associated with the occurrence of the primary endpoint.

CONCLUSION

Our study could not demonstrate a prognostic value of ¹⁸F-FDG PET/CT in IE, but confirms high diagnostic performance, which may compromise prognostic significance by accelerated optimal treatment because of earlier diagnostic certainty.

‘TAVR Infected Pseudomonas Endocarditis’: a case report

Pseudomonas aeruginosa (P. aeruginosa) rarely causes infective endocarditis (IE), previously reported for approximately 3% of all patients with IE.¹ Most commonly, the infection occurs in intravenous drug users (IVDU) as right-sided endocarditis, noting presentations of P. aeruginosa IE without history of intravenous drug to be extremely rare, finding only a few cases reported in the literature. However there are increasing reports of cardiovascular implantable electronic device–related and prosthetic heart valve infections caused by this pathogen in non-IVDUs.² This report will focus on the clinical presentation, management, and outcome of P. aeruginosa endocarditis in an 89-year-old patient with a transcatheter aortic valve replacement (TAVR). Medical management was pursued due to the patient’s underlying comorbidities. Long-term suppressive antibiotic therapy with delafloxacin was successful in maintaining negative blood cultures, despite an allergy to levofloxacin and ciprofloxacin.

18F-FDG PET/CT improves diagnostic certainty in native and prosthetic valve Infective Endocarditis over the modified Duke Criteria

BACKGROUND

International guidance recognizes the shortcomings of the modified Duke Criteria (mDC) in diagnosing infective endocarditis (IE) when transoesophageal echocardiography (TOE) is equivocal. 18F-FDG PET/CT (PET) has proven benefit in prosthetic valve endocarditis (PVE), but is restricted to extracardiac manifestations in native disease (NVE). We investigated the incremental benefit of PET over the mDC in NVE.

METHODS

Dual-center retrospective study (2010-2018) of patients undergoing myocardial suppression PET for NVE and PVE. Cases were classified by mDC pre- and post-PET, and evaluated against discharge diagnosis. Receiver Operating Characteristic (ROC) analysis and net reclassification index (NRI) assessed diagnostic performance. Valve standardized uptake value (SUV) was recorded.

RESULTS

69/88 PET studies were evaluated across 668 patients. At discharge, 20/32 had confirmed NVE, 22/37 PVE, and 19/69 patients required surgery. PET accurately re-classified patients from possible, to definite or rejected (NRI: NVE 0.89; PVE 0.90), with significant incremental benefit in both NVE (AUC 0.883 vs 0.750) and PVE (0.877 vs 0.633). Sensitivity and specificity were 75% and 92% in NVE; 87% and 86% in PVE. Duration of antibiotics and C-reactive Protein level did not impact performance. No diagnostic SUV cut-off was identified.

CONCLUSION

PET improves diagnostic certainty when combined with mDC in NVE and PVE.

Impact of Heparin Preadministration for Detection of Prosthetic Valve Endocarditis With FDG PET/CT

ABSTRACT

A 57-year-old woman with history of aortic and mitral valves replacement was referred to FDG PET/CT before valvular prosthesis renewal surgery. First FDG PET/CT was suboptimal for interpretation due to prominent physiological myocardial FDG uptake, despite patient preparation including 12 hours of fasting and low-carbohydrate, fat-rich diet. Therefore, scan was repeated with IV heparin preadministration at another day and revealed focal FDG uptake on the region of prosthetic heart valves, suggesting endocarditis. FDG PET/CT has been proven to be a useful technique to detect endocarditis, but appropriate patient preparation for adequate suppression of physiological myocardial uptake is important. Heparin preadministration seems to be an important component of patient preparation.

FDG PET/CT in Cardiac Infection: Does It Matter? A Narrative Review

The limited performance of echocardiography in specific infectious processes involving the heart led to the search for additional diagnostic tools. Fluorodeoxyglucose positron emission tomography computed tomography (FDG PET/CT) has been proposed for its diagnostic abilities in several infectious diseases including cardiac infections. A literature review of studies evaluating FDG PET/CT in native valve infective endocarditis (IE), prosthetic valve IE, cardiac implantable electrical device (CIED) infection, and left ventricular assist device (LVAD) infection is presented, focusing on studies published in recent years. Overall, in prosthetic valve endocarditis (PVE), FDG PET/CT demonstrate high sensitivity (73-93%) and specificity (80-95%), while in native valve endocarditis (NVE) the sensitivity is very low (22-68%), with high specificity (97-100%) similar to PVE. For CIED, LVAD infection, and transcatheter aortic valve implantation associated endocarditis, data come from small studies and show good diagnostic performance of FDG PET/CT. International guidelines are increasingly recommending FDG PET/CT for the diagnosis of specific conditions of cardiac infections. Beyond the diagnostic performance ability, few studies have evaluated the added benefit of FDG PET/CT in terms of clinical outcomes of patients with suspected cardiac infection. This should be the focus in future studies.

Expanding utility of cardiac computed tomography in infective endocarditis: A contemporary review

There is increasing evidence on the utility of cardiac computed tomography (CCT) in infective endocarditis (IE) to investigate the valvular pathology, the extra-cardiac manifestations of IE and pre-operative planning. CCT can assist in the diagnosis of perivalvular complications, such as pseudoaneurysms and abscesses, and can help identify embolic events to the lungs or systemic vasculature. CCT has also been shown to be beneficial in the pre-operative planning of patients by delineating the coronary artery anatomy and the major cardiovascular structures in relation to the sternum. Finally, hybrid nuclear/computed tomography techniques have been shown to increase the diagnostic accuracy in prosthetic valve endocarditis. This manuscript aims to provide a contemporary update of the existing evidence base for the use of CCT in IE.

Nuclear Imaging in Pediatric Cardiology: Principles and Applications

Nuclear imaging plays a unique role within diagnostic imaging since it focuses on cellular and molecular processes. Using different radiotracers and detection techniques such as the single photon emission scintigraphy or the positron emission tomography, specific parameters can be assessed: myocardial perfusion and viability, pulmonary perfusion, ventricular function, flow and shunt quantification, and detection of inflammatory processes. In pediatric and congenital cardiology, nuclear imaging can add complementary information compared to other imaging modalities such as echocardiography or magnetic resonance imaging. In this state-of-the-art paper, we appraise the different techniques in pediatric nuclear imaging, evaluate their advantages and disadvantages, and discuss the current clinical applications.

Infective Endocarditis in the Elderly: Challenges and Strategies

The specific management of infective endocarditis (IE) in elderly patients is not specifically addressed in recent guidelines despite its increasing incidence and high mortality in this population. The term "elderly" corresponds to different ages in the literature, but it is defined by considerable comorbidity and heterogeneity. Cancer incidence, specifically colorectal cancer, is increased in older patients with IE and impacts its outcome. Diagnosis of IE in elderly patients is challenging due to the atypical presentation of the disease and the lower performance of imaging studies. Enterococcal etiology is more frequent than in younger patients. Antibiotic treatment should prioritize diminishing adverse effects and drug interactions while maintaining the best efficacy, as surgical treatment is less commonly performed in this population due to the high surgical risk. The global assessment of elderly patients with IE, with particular attention to frailty and geriatric profiles, should be performed by multidisciplinary teams to improve disease management in this population.

Diagnostic value of FDG PET/CT imaging in patients with surgically managed infective endocarditis: results of a retrospective analysis at a tertiary center

BACKGROUND

We assessed the diagnostic value of FDG PET/CT in a real-world cohort of patients with surgically managed infective endocarditis (IE).

METHODS

We performed a retrospective analysis of all patients hospitalized in a tertiary IE referral medical center from January 2014 to October 2018 fulfilling the following criteria: ICD-10 code for IE and OPS code for both, heart surgery and FDG PET/CT.

RESULTS

Final analysis included 29 patients, whereof 28 patients had surgically proven IE. FDG PET/CT scan was true-positive in 15 patients (sensitivity (SEN) 56%) and false-negative in 12 patients. Combination of Duke criteria (DC) with FDG PET/CT scan resulted in gain of SEN for all patients with confirmed IE (SEN of DC 79% vs SEN of combination DC and FDG PET/CT 89%), driven by a relevant gain in PVE patients only (SEN of DC 78% vs SEN of combination DC and FDG PET/CT 94%). Interestingly, higher prosthesis age was observed in patients with false-negative scans.

CONCLUSIONS

We found a SEN of 56% for FDG PET/CT in a real-world cohort of patients with surgically proven IE which was associated with a 16% gain of IE diagnosis in patients with PVE when combined with DC.

Infective Endocarditis: Still More Challenges Than Convictions

After fourteen decades of medical and technological evolution, infective endocarditis continues to challenge physicians in its daily diagnosis and management. Its increasing incidence, demographic shifts (affecting older patients), microbiology with higher rates of Staphylococcus infection, still frequent serious complications and substantial mortality make endocarditis a very complex disease. Despite this, innovations in the diagnosis, involving microbiology and imaging, and improvements in intensive care and cardiac surgical techniques, materials and timing can impact the prognosis of this disease. Ongoing challenges persist, including rethinking prophylaxis, improving the diagnosis criteria comprising blood culture-negative endocarditis and prosthetic valve endocarditis, timing of surgical intervention, and whether to perform surgery in the presence of ischemic stroke or in intravenous drug users. A combined strategy on infective endocarditis is crucial, involving advanced clinical decisions and protocols, a multidisciplinary approach, national healthcare organization and health policies to achieve better results for our patients.

Four decades of experience of prosthetic valve endocarditis reflect a high variety of diverse pathogens

Prosthetic valve endocarditis (PVE) remains a serious condition with a high mortality rate. Precise identification of the PVE-associated pathogen/s and their virulence is essential for successful therapy, and patient survival. The commonly described PVE-associated pathogens are staphylococci, streptococci and enterococci, with Staphylococcus aureus being the most frequently diagnosed species. Furthermore, multi-drug resistance pathogens are increasing in prevalence, and continue to pose new challenges mandating a personalized approach. Blood cultures in combination with echocardiography are the most common methods to diagnose PVE, often being the only indication, it exists. In many cases, the diagnostic strategy recommended in the clinical guidelines does not identify the precise microbial agent and to frequently, false negative blood cultures are reported. Despite the fact that blood culture findings are not always a good indicator of the actual PVE agent in the valve tissue, only a minority of re-operated prostheses are subjected to microbiological diagnostic evaluation. In this review, we focus on the diversity and the complete spectrum of PVE-associated bacterial, fungal and viral pathogens in blood, and prosthetic heart valve, their possible virulence potential, and their challenges in making a microbial diagnosis. We are curious to understand if the unacceptable high mortality of PVE is associated with the high number of negative microbial findings in connection with a possible PVE. Herein, we discuss the possibilities and limits of the diagnostic methods conventionally used and make recommendations for enhanced pathogen identification. We also show possible virulence factors of the most common PVE-associated pathogens and their clinical effects. Based on blood culture, molecular biological diagnostics, and specific valve examination, better derivations for the antibiotic therapy as well as possible preventive intervention can be established in the future.

Accuracy of 18F-FDG PET/CT in patients with the suspicion of cardiac implantable electronic device infections

BACKGROUND

Utility of 18F-FDG PET/CT in diagnosing infective endocarditis (IE) associated with cardiac implantable electronic devices (CIEDs) is not well established. Current ESC guidelines recommend the use of FDG-PET imaging in patients with CIEDs and positive blood cultures, but the number of studies evaluating the diagnostic performance of FDG-PET imaging in these patients remain limited. Our objective was to assess the diagnostic yield of 18F-FDG PET/CT in patients with suspected CIED infections, differentiating between pocket infection (PI) and lead infection (CIED-IE).

METHODS AND RESULTS

From 2013 to 2018, all patients (n = 63) admitted to a hospital with suspected CIED infection were prospectively recruited, undergoing a diagnostic work-up including a PET/CT. Explanted devices and material from the pocket were cultured. 14 cases corresponded to isolated PI and 13 were categorized as CIED-IE. Considering radionuclide uptake in the intracardiac portion of the lead, sensitivity and specificity of PET/CT for CIED-IE were 38.5% and 98.0%, respectively. Positive (19.2) and negative (0.6) likelihood ratio values, 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 when negative. For PI, sensitivity and specificity were 72.2% and 95.6%, respectively.

CONCLUSIONS

The yield of 18F-FDG PET/CT for suspected CIED infections differs depending on the site of infection. Due to very high specificity but poor sensitivity, negative studies must be interpreted with caution if the suspicion of CIED-IE is high.