Diagnostic value of imaging in infective endocarditis: a systematic review

The [99mTc]Tc-HMPAO-labelled white blood cell SPECT/CT as a novel criterion for infective endocarditis diagnosis

AIMS

Infective endocarditis (IE) poses a significant clinical challenge, necessitating nuanced diagnostic tools for early and accurate detection. The diagnostic role of the hybrid technique of single-photon emission tomography-computed tomography with technetium-99 m-hexamethylpropyleneamine oxime-labelled leukocytes ([99mTc]Tc-HMPAO-SPECT/CT) has evolved in recent years. This single-center study assessed whether the recent inclusion in the 2023 European Society of Cardiology modified diagnostic criteria of IE (2023 ESC) of infectious lesions detected with [99mTc]Tc-HMPAO-SPECT/CT affects their diagnostic performance.

METHODS AND RESULTS

Between 2015 and 2019, we enrolled 205 consecutive adults with suspected IE. All participants underwent [99mTc]Tc-HMPAO-SPECT/CT scans (370-740 MBq). Scans were deemed positive in the presence of intracardiac abnormal tracer uptake and/or within the cardiac implantable electronic device. Patients were prospectively followed-up for 12 ± 10 months. Local device infection (LDI) or IE was diagnosed in 75 (36.6 %) patients, while 72 (35.1 %) [99mTc]Tc-HMPAO-SPECT/CT results returned positive. Moreover, extracardiac infectious foci were detected in 25 % of [99mTc]Tc-HMPAO-SPECT/CT scans. The inclusion of both intracardiac and extracardiac lesions detected with [99mTc]Tc-HMPAO-SPECT/CT yields significantly higher sensitivity (p = 0.003) and negative predictive value (NPV) (p = 0.009).

CONCLUSION

The inclusion of [99mTc]Tc-HMPAO-SPECT/CT into the IE diagnostic work-up improves the appropriate classification of patients. For patients with IE, the extended inclusion of lesions detected with [99mTc]Tc-HMPAO-SPECT/CT in the ESC 2023 diagnostic criteria significantly improves sensitivity and NPV while reducing potential IE misdiagnoses. This pioneering imaging modality is poised to become an integral component of clinical practice, promising to advance IE diagnosis and management.

Evidence-Based Data on the Diagnostic Role and Clinical Usefulness of [18F]FDG PET/CT in Endocarditis and Cardiac Device Infections

Infective endocarditis and infection of cardiac devices are conditions characterized by high morbidity and mortality, thus requiring a prompt diagnosis. Advanced imaging modalities are often required in the management of infectious endocarditis according to guidelines. The aim of this review is to collect and describe evidence-based knowledge about the diagnostic role and clinical usefulness of [18F]FDG PET/CT in endocarditis and cardiac device infections based on published systematic reviews and meta-analyses on this topic and on recent guidelines. [18F]FDG PET/CT is recommended only in selected cases. This imaging method has good diagnostic accuracy in detecting prosthetic valve endocarditis and cardiac device infection. Furthermore, it can identify extra-cardiac infectious foci changing the clinical management in a significant percentage of cases.

Cardiac computed tomography in infective endocarditis: "bridging the detection gap"

Infective Endocarditis (IE) remains a significant health challenge. Despite an increasing awareness, mortality is high and has remained largely unchanged over recent decades. Early diagnosis of IE is imperative and to assist clinicians several diagnostic criteria have been proposed. The best known are the Duke criteria. Originally published in 1994, these criteria have undergone significant modifications. This manuscript provides a timeline of the successive changes that have been made over the last 30 years. Changes which to a large degree have reflected both the evolving epidemiology of IE and the proliferation and increasing availability of advanced multi-modality imaging. Importantly, many of these changes now form part of societal guidelines for the diagnosis of IE. To provide validation for the incorporation of cardiac computed tomography (CT) in current guidelines, the manuscript demonstrates a spectrum of pictorial case studies that re-enforce the utility and growing importance of early cardiac CT in the diagnosis and treatment of suspected IE.

Transcatheter Aortic Valve-in-Valve Implantation in a Patient Due to the Degeneratation of the Biointegral Valve Conduit as a Result of Previous Infectious Endocarditis

Graft infection, fistula, and mediastinitis are reported among the serious cardiovascular complications after a Bentall procedure. Surgery associated with antimicrobial treatment is usually recommended but not easily feasible in most cases. In this report, we describe a case of successful valve-in-valve (ViV) transcatheter aortic valve replacement (TAVR) in a patient with a degenerated bioconduit from a previously healed infectious endocarditis (IE). The TAVR procedure has been demonstrated to be a therapeutic option in selected cases with a previous history of IE who have been fully treated with antimicrobial therapy and who present a low risk of local re-infection and are deemed at prohibitive or high risk for surgical replacement. Data on TAVR on a bioconduit after a Bentall procedure are scarce. The present case underlines that a long follow-up and individualized treatment could improve the prognosis in patients with a history of prosthetic valve and aortic graft infection and severe valve dysfunction who cannot undergo surgical treatment. The 18F-labeled fluoro-2-deoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) result could be successfully employed in the decision algorithm. Long-term antibiotic treatment, which could be lifelong in some instances, could be a reasonable choice when the risk of recurrence is associated with the risk for the patient's life.

Value of Time-Resolved Cardiac CT in Children and Young Adults with Congenital Heart Disease and Infective Endocarditis

BACKGROUND

Diagnosis of infective endocarditis (IE) can be challenging due to negative blood cultures and diagnostic limitations of various imaging modalities. Transesophageal echocardiography (TEE) is the gold standard imaging modality for visualization of valvular vegetations. However, due to the anterior location of the pulmonary valve, post-surgical changes, and sedation requirement, TEE can be challenging in the pediatric population. The aim of this study was to assess the value of Cardiac CT (CCT) for diagnosis of IE in children and young adults with congenital heart disease (CHD).

METHODS

This is a single-center retrospective study of pediatric patients with CHD and diagnosis of IE who underwent CCT from 2018 to 2022. Data collected included age, gender, cardiac diagnosis, clinical presentation, echocardiographic/CCT findings, and blood culture results. In addition, modified Duke criteria (MDC) for the diagnosis of IE were applied with and without CCT findings as the diagnostic imaging criterion.

RESULTS

Fourteen patients were included in this study with a median age of 11 years old. Nine patients were female. Ten patients had IE of the RV-PA conduit and four patients had IE of the aortic valve. Using MDC, 4 patients had definite IE. After including CCT findings, 11 patients (79%) met MDC for definite IE. Blood cultures were positive in 12 patients. CCT revealed the following complications: thromboembolic findings/pseudoaneurysms in 5 patients each and prosthetic valve perforation/prosthetic valve leak in one patient each.

CONCLUSIONS

This study reinforces the complimentary role of CCT to echocardiography in the work-up and diagnosis of IE in patients with CHD. With further improvement in lowering radiation exposure, CCT may have a key role in the diagnostic work-up of endocarditis and could be implemented in the diagnostic criteria of IE.

Native Infective Endocarditis: A State-of-the-Art-Review

Native valve infective endocarditis (NVE) is a global phenomenon, defined by infection of a native heart valve and involving the endocardial surface. The causes and epidemiology of the disease have evolved in recent decades, with a doubling of the average patient age. A higher incidence was observed in patients with implanted cardiac devices that can result in right-sided infection of the tricuspid valve. The microbiology of the disease has also changed. Previously, staphylococci, which are most often associated with health-care contact and invasive procedures, were the most common cause of the disease. This has now been superseded by streptococci. While innovative diagnostic and therapeutic strategies have emerged, mortality rates have not improved and remain at 30%, which is higher than that for many cancer diagnoses. The lack of randomized trials and logistical constraints impede clinical management, and long-standing controversies such as the use of antibiotic prophylaxis persist. This state of the art review addresses clinical practice, controversies, and strategies to combat this potentially devastating disease. A multidisciplinary team will be established to provide care for patients with presumptive NVE. The composition of the team will include specialists in cardiology, cardiovascular surgery, and infectious disease. The prompt administration of combination antimicrobial therapy is essential for effective NVE treatment. Additionally, a meticulous evaluation of each patient is necessary in order to identify any indications for immediate valve surgery. With the intention of promoting a more comprehensive understanding of the procedural management of native infective endocarditis and to furnish clinicians with a reference, the current evidence for the utilization of distinct strategies for the diagnosis and treatment of NVE are presented.

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.

Imaging in Infective Endocarditis-Current Opinions and Trends in Cardiac Computed Tomography

Infective endocarditis is a rare disease with an increasing incidence and an unaltered high mortality rate, despite medical development. Imaging plays an integrative part in the diagnosis of infective endocarditis, with echocardiography as the initial diagnostic test. Research data in the utility of cardiac computed tomography (CCT) in the diagnostic algorithm of IE are rising, which indicates its importance in detection of IE-related lesion along with the exclusion of coronary artery disease. The latest 2023 European Society of Cardiology Guidelines in the management of IE classified CCT as class of recommendation I and level of evidence B in detection of both valvular and paravalvular lesions in native and prosthetic valve endocarditis. This review article provides a comprehensive and contemporary review of the role of CCT in the diagnosis of IE, the optimization of acquisition protocols, the morphology characteristics of IE-related lesions, the published data of the diagnostic performance of CCT in comparison to echocardiography as the state-of-art method, as well as the limitations and future possibilities.

18F-FDG PET/CT and Radiolabeled Leukocyte SPECT/CT Imaging for the Evaluation of Cardiovascular Infection in the Multimodality Context: ASNC Imaging Indications (ASNC I2) Series Expert Consensus Recommendations From ASNC, AATS, ACC, AHA, ASE, EANM, HRS, IDSA, SCCT, SNMMI, and STS

This document on cardiovascular infection, including infective endocarditis, is the first in the American Society of Nuclear Cardiology Imaging Indications (ASNC I2) series to assess the role of radionuclide imaging in the multimodality context for the evaluation of complex systemic diseases with multisocietal involvement including pertinent disciplines. A rigorous modified Delphi approach was used to determine consensus clinical indications, diagnostic criteria, and an algorithmic approach to diagnosis of cardiovascular infection including infective endocarditis. Cardiovascular infection incidence is increasing and is associated with high morbidity and mortality. Current strategies based on clinical criteria and an initial echocardiographic imaging approach are effective but often insufficient in complicated cardiovascular infection. Radionuclide imaging with fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (CT) and single photon emission computed tomography/CT leukocyte scintigraphy can enhance the evaluation of suspected cardiovascular infection by increasing diagnostic accuracy, identifying extracardiac involvement, and assessing cardiac implanted device pockets, leads, and all portions of ventricular assist devices. This advanced imaging can aid in key medical and surgical considerations. Consensus diagnostic features include focal/multifocal or diffuse heterogenous intense 18F-FDG uptake on valvular and prosthetic material, perivalvular areas, device pockets and leads, and ventricular assist device hardware persisting on non-attenuation corrected images. There are numerous clinical indications with a larger role in prosthetic valves, and cardiac devices particularly with possible infective endocarditis or in the setting of prior equivocal or non-diagnostic imaging. Illustrative cases incorporating these consensus recommendations provide additional clarification. Future research is necessary to refine application of these advanced imaging tools for surgical planning, to identify treatment response, and more.

PET/CT Imaging of Infectious Diseases: Overview of Novel Radiopharmaceuticals

Infectious diseases represent one of the most common causes of hospital admission worldwide. The diagnostic work-up requires a complex clinical approach, including laboratory data, CT and MRI, other imaging tools, and microbiologic cultures. PET/CT with 18F-FDG can support the clinical diagnosis, allowing visualization of increased glucose metabolism in activated macrophages and monocytes; this tracer presents limits in differentiating between aseptic inflammation and infection. Novel PET radiopharmaceuticals have been developed to overcome these limits; 11C/18F-labeled bacterial agents, several 68Ga-labeled molecules, and white blood cells labeled with 18F-FDG are emerging PET tracers under study, showing interesting preliminary results. The best choice among these tracers can be unclear. This overview aims to discuss the most common diagnostic applications of 18F-FDG PET/CT in infectious diseases and, as a counterpoint, to describe and debate the advantages and peculiarities of the latest PET radiopharmaceuticals in the field of infectious diseases, which will probably improve the diagnosis and prognostic stratification of patients with active infectious diseases.

Role of echocardiography in the diagnosis and clinical management of infective endocarditis

Infective endocarditis (IE) is a deadly disease, constituting both diagnostic and treatment challenges. A positive outcome requires rapid and accurate diagnosis, and for that, echocardiography unequivocally remains the cornerstone. Transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) have complementary roles and have been markedly improved during the last decades. The transthoracic modality is the recommended first-line approach but may only be sufficient in patients where the probability of IE is low and/or with clear acoustic windows, especially in patients with right-sided IE. The transesophageal modality is superior to TTE in most aspects and is recommended for all other patients. Both TTE and TEE may delineate vegetation location and size, assess for paravalvular extension of infection, and have the added advantage of defining the hemodynamic effects of valvular or device infection. However, echocardiography still has significant limitations, and novel imaging techniques are increasingly being exploited to improve diagnostic potential. Cardiac computed tomography (CT) performs better than TEE in the detection of abscess or pseudoaneurysm, while magnetic resonance imaging (MRI) has limited value in the diagnostic phase of IE but adds knowledge to the evaluation of extracardiac events. Nuclear molecular techniques are evolving as key supplementary methods in difficult-to-diagnose cases. Although newer imaging modalities are undergoing preliminary evaluation and multimodal imaging will play an increasing role in IE, echocardiography will continue to be pivotal in patients with IE for the foreseeable future.

18F-FDG PET/CT and radiolabeled leukocyte SPECT/CT imaging for the evaluation of cardiovascular infection in the multimodality context: ASNC Imaging Indications (ASNC I2) Series Expert Consensus Recommendations from ASNC, AATS, ACC, AHA, ASE, EANM, HRS, IDSA, SCCT, SNMMI, and STS

This document on cardiovascular infection, including infective endocarditis, is the first in the American Society of Nuclear Cardiology Imaging Indications (ASNC I2) series to assess the role of radionuclide imaging in the multimodality context for the evaluation of complex systemic diseases with multi-societal involvement including pertinent disciplines. A rigorous modified Delphi approach was used to determine consensus clinical indications, diagnostic criteria, and an algorithmic approach to diagnosis of cardiovascular infection including infective endocarditis. Cardiovascular infection incidence is increasing and is associated with high morbidity and mortality. Current strategies based on clinical criteria and an initial echocardiographic imaging approach are effective but often insufficient in complicated cardiovascular infection. Radionuclide imaging with 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (CT) and single photon emission computed tomography/CT leukocyte scintigraphy can enhance the evaluation of suspected cardiovascular infection by increasing diagnostic accuracy, identifying extracardiac involvement, and assessing cardiac implanted device pockets, leads, and all portions of ventricular assist devices. This advanced imaging can aid in key medical and surgical considerations. Consensus diagnostic features include focal/multi-focal or diffuse heterogenous intense 18F-FDG uptake on valvular and prosthetic material, perivalvular areas, device pockets and leads, and ventricular assist device hardware persisting on non-attenuation corrected images. There are numerous clinical indications with a larger role in prosthetic valves, and cardiac devices particularly with possible infective endocarditis or in the setting of prior equivocal or non-diagnostic imaging. Illustrative cases incorporating these consensus recommendations provide additional clarification. Future research is necessary to refine application of these advanced imaging tools for surgical planning, to identify treatment response, and more.

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.

The Clinical Challenge of Prosthetic Valve Endocarditis: JACC Focus Seminar 3/4

During the past 6 decades, there have been numerous changes in prosthetic valve endocarditis (PVE), currently affecting an older population and increasing in incidence in patients with transcatheter-implanted valves. Significant microbiologic (molecular biology) and imaging diagnostic (fluorine-18 fluorodeoxyglucose-positron emission tomography/computed tomography) advances have been incorporated into the 2023 Duke-International Society for Cardiovascular Infectious Diseases infective endocarditis diagnostic criteria, thus increasing the diagnostic sensitivity for PVE without sacrificing specificity in validation studies. PVE is a life-threatening disease requiring management by multidisciplinary endocarditis teams in cardiac centers to improve outcomes. Novel surgical options are now available, and an increasing set of patients may avoid surgical intervention despite indication. Selected patients may complete parenteral or oral antimicrobial treatment at home. Finally, patients with prosthetic valves implanted surgically or by the transcatheter approach are candidates for antibiotic prophylaxis before invasive dental procedures.

Recent Insights Into Native Valve Infective Endocarditis: JACC Focus Seminar 4/4

This focused review highlights the latest issues in native valve infective endocarditis. Native valve disease moderately increases the risk of developing infective endocarditis. In 2023, new diagnostic criteria were published by the Duke-International Society of Cardiovascular Infectious Diseases group. New pathogens were designated as typical, and findings on computed tomography imaging were included as diagnostic criteria. It is now recognized that a multidisciplinary approach to care is vital, and the role of an "endocarditis team" is highlighted. Recent studies have suggested that a transition from intravenous to oral antibiotics in selected patients may be reasonable, and the role of long-acting antibiotics is discussed. It is also now clear that an aggressive surgical approach can be life-saving in some patients. Finally, results of several recent studies have suggested there is an association between dental and other invasive procedures and an increased risk of developing infective endocarditis. Moreover, data indicate that antibiotic prophylaxis may be effective in some scenarios.

18F-FDG PET/CT and radiolabeled leukocyte SPECT/CT imaging for the evaluation of cardiovascular infection in the multimodality context: ASNC Imaging Indications (ASNC I2) Series Expert Consensus Recommendations from ASNC, AATS, ACC, AHA, ASE, EANM, HRS, IDSA, SCCT, SNMMI, and STS

This document on cardiovascular infection, including infective endocarditis, is the first in the American Society of Nuclear Cardiology Imaging Indications (ASNC I2) series to assess the role of radionuclide imaging in the multimodality context for the evaluation of complex systemic diseases with multi-societal involvement including pertinent disciplines. A rigorous modified Delphi approach was used to determine consensus clinical indications, diagnostic criteria, and an algorithmic approach to diagnosis of cardiovascular infection including infective endocarditis. Cardiovascular infection incidence is increasing and is associated with high morbidity and mortality. Current strategies based on clinical criteria and an initial echocardiographic imaging approach are effective but often insufficient in complicated cardiovascular infection. Radionuclide imaging with 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (CT) and single photon emission computed tomography/CT leukocyte scintigraphy can enhance the evaluation of suspected cardiovascular infection by increasing diagnostic accuracy, identifying extracardiac involvement, and assessing cardiac implanted device pockets, leads, and all portions of ventricular assist devices. This advanced imaging can aid in key medical and surgical considerations. Consensus diagnostic features include focal/multi-focal or diffuse heterogenous intense 18F-FDG uptake on valvular and prosthetic material, perivalvular areas, device pockets and leads, and ventricular assist device hardware persisting on non-attenuation corrected images. There are numerous clinical indications with a larger role in prosthetic valves, and cardiac devices particularly with possible infective endocarditis or in the setting of prior equivocal or non-diagnostic imaging. Illustrative cases incorporating these consensus recommendations provide additional clarification. Future research is necessary to refine application of these advanced imaging tools for surgical planning, to identify treatment response, and more.

18F-FDG PET/CT and radiolabeled leukocyte SPECT/CT imaging for the evaluation of cardiovascular infection in the multimodality context: ASNC Imaging Indications (ASNC I2) Series Expert Consensus Recommendations from ASNC, AATS, ACC, AHA, ASE, EANM, HRS, IDSA, SCCT, SNMMI, and STS

This document on cardiovascular infection, including infective endocarditis, is the first in the American Society of Nuclear Cardiology Imaging Indications (ASNC I2) series to assess the role of radionuclide imaging in the multimodality context for the evaluation of complex systemic diseases with multi-societal involvement including pertinent disciplines. A rigorous modified Delphi approach was used to determine consensus clinical indications, diagnostic criteria, and an algorithmic approach to diagnosis of cardiovascular infection including infective endocarditis. Cardiovascular infection incidence is increasing and is associated with high morbidity and mortality. Current strategies based on clinical criteria and an initial echocardiographic imaging approach are effective but often insufficient in complicated cardiovascular infection. Radionuclide imaging with 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and single photon emission computed tomography/CT leukocyte scintigraphy can enhance the evaluation of suspected cardiovascular infection by increasing diagnostic accuracy, identifying extracardiac involvement, and assessing cardiac implanted device pockets, leads, and all portions of ventricular assist devices. This advanced imaging can aid in key medical and surgical considerations. Consensus diagnostic features include focal/multi-focal or diffuse heterogenous intense 18F-FDG uptake on valvular and prosthetic material, perivalvular areas, device pockets and leads, and ventricular assist device hardware persisting on non-attenuation corrected images. There are numerous clinical indications with a larger role in prosthetic valves, and cardiac devices particularly with possible infective endocarditis or in the setting of prior equivocal or non-diagnostic imaging. Illustrative cases incorporating these consensus recommendations provide additional clarification. Future research is necessary to refine application of these advanced imaging tools for surgical planning, to identify treatment response, and more.

Total-Body PET/CT Applications in Cardiovascular Diseases: A Perspective Document of the SNMMI Cardiovascular Council

Digital PET/CT systems with a long axial field of view have become available and are emerging as the current state of the art. These new camera systems provide wider anatomic coverage, leading to major increases in system sensitivity. Preliminary results have demonstrated improvements in image quality and quantification, as well as substantial advantages in tracer kinetic modeling from dynamic imaging. These systems also potentially allow for low-dose examinations and major reductions in acquisition time. Thereby, they hold great promise to improve PET-based interrogation of cardiac physiology and biology. Additionally, the whole-body coverage enables simultaneous assessment of multiple organs and the large vascular structures of the body, opening new opportunities for imaging systemic mechanisms, disorders, or treatments and their interactions with the cardiovascular system as a whole. The aim of this perspective document is to debate the potential applications, challenges, opportunities, and remaining challenges of applying PET/CT with a long axial field of view to the field of cardiovascular disease.

Case report: accidental finding of mobile pacemaker lead structures

We present a case of a 79-year-old man on apixaban for atrial fibrillation who suffered multiple ischaemic strokes and was found to have mobile structures attached to his pacemaker lead on transesophageal echocardiography. Based on the Modified Duke Criteria, there was no evidence of infectious endocarditis. Since there were no signs of a patent foramen ovale or arteriovenous malformations in the lungs, the mobile structures probably were not the cause of the ischaemic strokes. After the visualisation of the mobile structures, apixaban was switched to dabigatran with a clear decrease in the size of the structures. Blood cultures remained negative and there was no fever or increase in inflammatory parameters. It was therefore suspected that the structures were thrombus material rather than vegetations of infectious endocarditis.There is uncertainty surrounding the clinical relevance and indication for treatment of incidentally found mobile structures on pacemaker leads. Multiple studies with different imaging modalities show a significant difference in the prevalence of thrombi. More studies with longer follow-ups are needed to investigate the prevalence and need for treatment of these incidentally found structures on pacemaker leads.

Update on the epidemiology, diagnosis, and management of infective endocarditis: A review

Despite advancements in the diagnosis and treatment of infective endocarditis (IE), the burden of IE has remained relatively high over the past decade. With an ageing population and an increasing proportion of healthcare-associated IE, the epidemiology of IE has undergone significant changes. Staphylococcus aureus has evolved as the most common causative microorganism, even in most low- and middle-income countries. Several imaging modalities and novel microbiological tests have emerged to facilitate the diagnosis of IE. Outpatient parenteral antibiotic treatment and oral step-down antibiotic treatment have become new trends for the management of IE. Early surgical intervention, particularly within seven days, should be considered in cases of IE with appropriate surgical indications. We comprehensively review the updated epidemiology, microbiology, diagnosis, and management of IE.

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.

Contemporary applications of multimodality imaging in infective endocarditis

INTRODUCTION

Infective endocarditis (IE) is an increasingly important condition with significant morbidity and mortality. With advancements in cardiovascular interventions including prosthetic valve implantation and utilization of intracardiac devices, the prevalence of IE is rising in the modern era. Early detection and management of this condition are critical.

AREAS COVERED

This review presents a contemporary review of the applications of multi-modality imaging in IE, taking a comparative approach of the various imaging modalities.

EXPERT OPINION

Transthoracic and transesophageal echocardiography are essential imaging modalities in establishing the diagnosis of IE, as well as evaluating for complications of IE. Other imaging modalities such as cardiac computed tomography and nuclear imaging play an important role as adjuvant imaging modalities for the evaluation of IE, particularly in prosthetic valve IE and cardiovascular implantable device associated IE. It is crucial to understand the strengths, weaknesses, and clinical application of each imaging modality, to improve the diagnosis, management, and outcomes of patients with IE.

18F- FDG PET/CT in reclassifying the probable diagnosis of IE - A review

In the diagnosis of infective endocarditis (IE), Modified Duke's criteria, coupled with clinical suspicion, serve as the guiding framework. For cases involving prosthetic valve endocarditis and infections affecting implantable devices, the use of metabolic imaging with 18 F-FDG PET/CT scans has gained prominence, as per the recommendations of the European Society of Cardiology guidelines. This imaging modality enhances sensitivity and specificity by identifying infective foci within the heart and extracardiac locations. Early utilization of these scans is crucial for confirming or ruling out IE, although caution is required to mitigate false positive responses, especially in the presence of ongoing inflammatory activity. A standardized ratio of ≥2.0 between FDG uptake around infected tissues and the blood pool has demonstrated a sensitivity of 100 % and specificity of 91 %. It is noteworthy that the sensitivity of FDG PET/CT varies, being lower for native valve and lead infections but considerably higher for prosthetic valve and pulse generator infections. This review provides a comprehensive overview of the advantages offered by FDG PET/CT in achieving a definitive diagnosis of IE.

Multimodal Cardiac Imaging in the Assessment of Patients Who Have Suffered a Cardioembolic Stroke: A Review

Cardioembolic strokes account for 20-25% of all ischaemic strokes, with their incidence increasing with age. Cardiac imaging plays a crucial role in identifying cardioembolic causes of stroke, with early and accurate identification affecting treatment, preventing recurrence, and reducing stroke incidence. Echocardiography serves as the mainstay of cardiac evaluation. Transthoracic echocardiography (TTE) is the first line in the basic evaluation of structural heart disorders, valvular disease, vegetations, and intraventricular thrombus. It can be used to measure chamber size and systolic/diastolic function. Trans-oesophageal echocardiography (TOE) yields better results in identifying potential cardioembolic sources of stroke and should be strongly considered, especially if TTE does not yield adequate results. Cardiac computed tomography and cardiac magnetic resonance imaging provide better soft tissue characterisation, high-grade anatomical information, spatial and temporal visualisation, and image reconstruction in multiple planes, especially with contrast. These techniques are useful in cases of inconclusive echocardiograms and can be used to detect and characterise valvular lesions, thrombi, fibrosis, cardiomyopathies, and aortic plaques. Nuclear imaging is not routinely used, but it can be used to assess left-ventricular perfusion, function, and dimensions and may be useful in cases of infective endocarditis. Its use should be considered on a case-by-case basis. The accuracy of each imaging modality depends on the likely source of cardioembolism, and the choice of imaging approach should be tailored to individual patients.

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.

Endocarditis after Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement (TAVR) use is gaining momentum as the mainstay for the treatment of aortic stenosis compared to surgical aortic valve replacement (SAVR). Unfortunately, TAVR-related infective endocarditis (TAVR-IE) is expected to be detected more and more as a result of the ever-expanding indications in younger patients. Given the overall poor prognosis of TAVR-IE, it is imperative that clinicians familiarize themselves with common presentations, major risk factors, diagnostic pitfalls, therapeutic approaches, and the prevention of TAVR-IE. Herein, we review all of the above in detail with the most updated available literature.

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.

Fungal Endocarditis: Pathophysiology, Epidemiology, Clinical Presentation, Diagnosis, and Management

Fungal endocarditis accounts for 1% to 3% of all infective endocarditis cases, is associated with high morbidity and mortality (>70%), and presents numerous challenges during clinical care. Candida spp. are the most common causes of fungal endocarditis, implicated in over 50% of cases, followed by Aspergillus and Histoplasma spp. Important risk factors for fungal endocarditis include prosthetic valves, prior heart surgery, and injection drug use. The signs and symptoms of fungal endocarditis are nonspecific, and a high degree of clinical suspicion coupled with the judicious use of diagnostic tests is required for diagnosis. In addition to microbiological diagnostics (e.g., blood culture for Candida spp. or galactomannan testing and PCR for Aspergillus spp.), echocardiography remains critical for evaluation of potential infective endocarditis, although radionuclide imaging modalities such as 18F-fluorodeoxyglucose positron emission tomography/computed tomography are increasingly being used. A multimodal treatment approach is necessary: surgery is usually required and should be accompanied by long-term systemic antifungal therapy, such as echinocandin therapy for Candida endocarditis or voriconazole therapy for Aspergillus endocarditis.

The Role of Echocardiography and Cardiac Computed Tomography in Diagnosis of Infective Endocarditis

BACKGROUND

Infective endocarditis (IE) is a rare disease with a high mortality rate and rising incidence, requiring timely and precise diagnosis in order to choose appropriate therapy. Imaging of morphologic lesions is an integrative part of diagnosis. Artifacts and the patient's habitus make echocardiography difficult to visualize advanced-form IE. Cardiac computed tomography (CCT) constantly shows an additive diagnostic value due to high resolution of cardiac anatomy. Conjecturally, joint application of both diagnostic tests improves overall sensitivity and specificity in diagnosing IE.

METHODS

Patients with definite IE underwent transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), and CCT. We analyzed valvular and paravalvular IE lesions in all three imaging methods and compared them to surgical or autopsy findings. We calculated sensitivity, specificity, diagnostic accuracy, and positive and negative predictive value of both imaging tests individually and jointly used.

RESULTS

We examined 78 patients, male to female ratio 2:1, mean age 52.29 ± 16.62. We analyzed 85 valves, 70 native valves, 13 prosthetic valves, and 2 corrected valves due to Ozaki procedure, along with a central shunt and 4 pacemaker leads. As a single test, the sensitivity and specificity of CCT, TTE, and TEE for valvular lesions were 91.6/20%, 65.5/57.9%, and 60/84%, and paravalvular lesions were 100/0%, 46/10.5%, and 14.7/100%. When combined together, sensitivity and specificity for valvular lesions rose to 96.6/0% and paravalvular lesions to 100/0%. We also analyzed the diagnostic performance for each test in single and mutual application, per specific IE lesion.

CONCLUSION

In the individual application, CCT in comparison to TTE and TEE shows better diagnostic performance in detection of valvular and paravalvular lesions. In joint application, there is a statistically significant difference in performance compared to their single use, especially in prosthetic valves and invasive forms of IE native valves.

The 2023 Duke-International Society for Cardiovascular Infectious Diseases Criteria for Infective Endocarditis: Updating the Modified Duke Criteria

The microbiology, epidemiology, diagnostics, and treatment of infective endocarditis (IE) have changed significantly since the Duke Criteria were published in 1994 and modified in 2000. The International Society for Cardiovascular Infectious Diseases (ISCVID) convened a multidisciplinary Working Group to update the diagnostic criteria for IE. The resulting 2023 Duke-ISCVID IE Criteria propose significant changes, including new microbiology diagnostics (enzyme immunoassay for Bartonella species, polymerase chain reaction, amplicon/metagenomic sequencing, in situ hybridization), imaging (positron emission computed tomography with 18F-fluorodeoxyglucose, cardiac computed tomography), and inclusion of intraoperative inspection as a new Major Clinical Criterion. The list of "typical" microorganisms causing IE was expanded and includes pathogens to be considered as typical only in the presence of intracardiac prostheses. The requirements for timing and separate venipunctures for blood cultures were removed. Last, additional predisposing conditions (transcatheter valve implants, endovascular cardiac implantable electronic devices, prior IE) were clarified. These diagnostic criteria should be updated periodically by making the Duke-ISCVID Criteria available online as a "Living Document."

Added value of semi-quantitative analysis of [18F]FDG PET/CT for the diagnosis of device-related infections in patients with a left ventricular assist device

AIMS

Left ventricular assist devices (LVADs) improve quality of life and survival in patients with advanced heart failure, but device-related infections (DRIs) remain cumbersome. We evaluated the diagnostic capability of [18F]FDG PET/CT, factors affecting its accuracy, and the additive value of semi-quantitative analysis for the diagnosis of DRI.

METHODS AND RESULTS

LVAD recipients undergoing [18F]FDG PET/CT between 2012 and 2020 for suspected DRI were retrospectively included. [18F]FDG PET/CT was performed and evaluated in accordance with EANM guidelines. The final diagnosis of DRI, based on multidisciplinary consensus and findings during surgery, whenever performed, was used as the reference for diagnosis. 41 patients were evaluated for 59 episodes of suspected DRI. The clinical evaluation established driveline infection in 32 (55%) episodes, central device infection in 6 (11%), and combined infection in 2 (4%). Visual analysis of [18F]FDG PET/CT achieved a sensitivity and specificity for driveline infections of 0.79 and 0.71, respectively, whereas semi-quantitative analysis achieved a sensitivity and specificity of 0.94 and 0.83, respectively. For central device component infection, visual analysis of [18F]FDG PET/CT achieved a sensitivity and specificity of 0.75 and 0.60, respectively. Semi-quantitative analysis using SUVratio achieved a sensitivity and specificity of 1.0 and 0.8, respectively. The increase of specificity for central component infection was statistically significant (P = 0.05).

CONCLUSIONS

[18F]FDG PET/CT reliably predicts the presence of DRI in LVAD recipients. Semi-quantitative analysis may increase the specificity of [18F]FDG PET/CT for the analysis of central device component infection and should be considered in equivocal cases after visual analysis.

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.

A New Clinical Prediction Rule for Infective Endocarditis in Emergency Department Patients With Fever: Definition and First Validation of the CREED Score

Background Infective endocarditis (IE) could be suspected in any febrile patients admitted to the emergency department (ED). This study was aimed at assessing clinical criteria predictive of IE and identifying and prospectively validating a sensible and easy-to-use clinical prediction score for the diagnosis of IE in the ED. Methods and Results We conducted a retrospective observational study, enrolling consecutive patients with fever admitted to the ED between January 2015 and December 2019 and subsequently hospitalized. Several clinical and anamnestic standardized variables were collected and evaluated for the association with IE diagnosis. We derived a multivariate prediction model by logistic regression analysis. The identified predictors were assigned a score point value to obtain the Clinical Rule for Infective Endocarditis in the Emergency Department (CREED) score. To validate the CREED score we conducted a prospective observational study between January 2020 and December 2021, enrolling consecutive febrile patients hospitalized after the ED visit, and evaluating the association between the CREED score values and the IE diagnosis. A total of 15 689 patients (median age, 71 [56-81] years; 54.1% men) were enrolled in the retrospective cohort, and IE was diagnosed in 267 (1.7%). The CREED score included 12 variables: male sex, anemia, dialysis, pacemaker, recent hospitalization, recent stroke, chest pain, specific infective diagnosis, valvular heart disease, valvular prosthesis, previous endocarditis, and clinical signs of suspect endocarditis. The CREED score identified 4 risk groups for IE diagnosis, with an area under the receiver operating characteristic curve of 0.874 (0.849-0.899). The prospective cohort included 13 163 patients, with 130 (1.0%) IE diagnoses. The CREED score had an area under the receiver operating characteristic curve of 0.881 (0.848-0.913) in the validation cohort, not significantly different from the one calculated in the retrospective cohort (P=0.578). Conclusions In this study, we propose and prospectively validate the CREED score, a clinical prediction rule for the diagnosis of IE in patients with fever admitted to the ED. Our data reflect the difficulty of creating a meaningful tool able to identify patients with IE among this general and heterogeneous population because of the complexity of the disease and its low prevalence in the ED setting.

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.

Advanced Imaging for Detection of Foci of Infection in Staphylococcus aureus Bacteremia- Can a Scan Save Lives?

Bloodstream infection or sepsis is a common cause of mortality globally. Staphylococcus aureus (S. aureus) is of particular concern, through its ability to seed metastatic infections in almost any organ after entering the bloodstream (S. aureus bacteraemia), often without localising signs. A positive blood culture for S. aureus bacteria should lead to immediate and urgent identification of the cause. Failure to detect a precise focus of infection is associated with higher mortality, sometimes despite appropriate antibiotics. This is likely due to the limited ability to effectively target therapy in occult lesions. Early detection of foci of metastatic S. aureus infection is therefore key for optimal diagnosis and subsequent therapeutic management. 18F-FDG-PET/CT and MRI offer us invaluable tools in the localisation of foci of S. aureus infection. Crucially, they may identify unexpected foci at previously unsuspected locations in the body, for example vertebral osteomyelitis in the absence of back pain. S. aureus bloodstream infections are further complicated by their microbiological recurrence; 18F-FDG-PET/CT provide a means of localising, thus enabling source control. More evidence is emerging as to the utility of 18F-FDG-PET/CT in this setting, perhaps even to the point of reducing mortality. 18 F-FDG-PET/MRI may have a similar impact. The available evidence demonstrates a need to investigate the impact of 18F-FDG-PET/CT and MRI scanning in clinical management and outcomes of S. aureus infection further in a randomised prospective clinical trial.

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.

Cardiovascular positron emission tomography: established and emerging role in cardiovascular diseases

Cardiac positron emission tomography (PET) imaging has established themselves firmly as excellent and reliable functional imaging modalities in assessment of the spectrum of coronary artery disease. With the explosion of technology advances and the dream of flow quantification now a reality, the value of PET is now well realized. Cardiac PET has proved itself as precise imaging modality that provides functional imaging of the heart in addition to anatomical imaging. It has established itself as one of the best available techniques for evaluation of myocardial viability. Hybrid PET/computed tomography provides simultaneous integration of coronary anatomy and function with myocardial perfusion and metabolism, thereby improving characterization of the dysfunctional area and chronic coronary artery disease. The availability of quantitative myocardial blood flow evaluation with PET provides additional prognostic information and increases diagnostic accuracy in the management of patients with coronary artery disease. Hybrid imaging seems to hold immense potential in optimizing management of cardiovascular diseases and furthering clinical research.

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.

Imaging glucose metabolism to reveal tumor progression

Purpose: To analyze and review the progress of glucose metabolism-based molecular imaging in detecting tumors to guide clinicians for new management strategies. Summary: When metabolic abnormalities occur, termed the Warburg effect, it simultaneously enables excessive cell proliferation and inhibits cell apoptosis. Molecular imaging technology combines molecular biology and cell probe technology to visualize, characterize, and quantify processes at cellular and subcellular levels in vivo. Modern instruments, including molecular biochemistry, data processing, nanotechnology, and image processing, use molecular probes to perform real-time, non-invasive imaging of molecular and cellular events in living organisms. Conclusion: Molecular imaging is a non-invasive method for live detection, dynamic observation, and quantitative assessment of tumor glucose metabolism. It enables in-depth examination of the connection between the tumor microenvironment and tumor growth, providing a reliable assessment technique for scientific and clinical research. This new technique will facilitate the translation of fundamental research into clinical practice.

Incidence and mortality of infective endocarditis in the last decade: a single center study

BACKGROUND

Infective endocarditis (IE) is a significant disease characterized by high mortality and complications. The aim of this study was to evaluate the incidence/100 000 inhabitants and the in-hospital mortality/100 000 inhabitants of IE during the last 10 years in the province of Ravenna.

METHODS AND RESULTS

We reviewed the public hospitals discharge database from January 2010 to December 2020 using the international classification of disease codification (ICD-9) for IE. We used the Italian national statistical institute (ISTAT) archive to estimate the number of Ravenna inhabitants/year. In 10 years, we identified a total of 407 patients with diagnosis of IE.The incidence of IE increased significantly from 6.29 cases/100 000 inhabitants in 2010 to 19.58 cases/100 000 inhabitants in 2020 ( P  < 0.001). Also, the in-hospital mortality from IE increased over the same number of years, from 1.8 deaths/100 000 inhabitants in 2010 to 4.4 deaths/100 000 inhabitants in 2020 ( P  < 0.001). The mortality rate (%) of IE over the years did not increase ( P = 0.565). Also, over the years there was no difference in the site of infection ( P  = 0.372), irrespective of the valve localization or type, native valve ( P  = 0.347) or prosthetic valve ( P  = 0.145). On logistic regression analysis, age was the only predictor of in-hospital mortality (odds ratio 1.045, 95% confidence interval: 1.015; 1.075, P  = 0.003).

CONCLUSIONS

Ravenna-based data on IE showed increased disease incidence but unchanged mortality rate over 10 years of follow-up. Age remains the sole predictor of population-based mortality, irrespective of the nature of the valve, native or substitute, and the organism detected on microbiology.

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.

"Vascular inflammation and cardiovascular disease: review about the role of PET imaging"

Inflammation characterizes all stages of atherothrombosis and provides a critical pathophysiological link between plaque formation and its acute rupture, leading to coronary occlusion and heart attack. In the last 20 years the possibility of quantifying the degree of inflammation of atherosclerotic plaques and, therefore, also of vascular inflammation aroused much interest. ¹⁸Fluoro-deoxy-glucose photon-emissions-tomography (¹⁸F-FDG-PET) is widely used in oncology for staging and searching metastases; in cardiology, the absorption of ¹⁸F-FDG into the arterial wall was observed for the first time incidentally in the aorta of patients undergoing PET imaging for cancer staging. PET/CT imaging with ¹⁸F-FDG and ¹⁸F-sodium fluoride (¹⁸F-NaF) has been shown to assess atherosclerotic disease in its molecular phase, when the process may still be reversible. This approach has several limitations in the clinical practice, due to lack of prospective data to justify their use routinely, but it's desirable to develop further scientific evidence to confirm this technique to detect high-risk patients for cardiovascular events.

Nuclear Methods for Immune Cell Imaging: Bridging Molecular Imaging and Individualized Medicine

Inflammation is a key mechanistic contributor to the progression of cardiovascular disease, from atherosclerosis through ischemic injury and overt heart failure. Recent evidence has identified specific roles of immune cell subpopulations in cardiac pathogenesis that diverges between individual patients. Nuclear imaging approaches facilitate noninvasive and serial quantification of inflammation severity, offering the opportunity to predict eventual outcome, stratify patient risk, and guide novel targeted molecular therapies against specific leukocyte subpopulations. Here, we will discuss the established and emerging nuclear imaging methods to label and track exogenous and endogenous immune cells, with a particular focus on clinical situations in which targeted molecular inflammation imaging would be advantageous. The expanding options for imaging inflammation provide the foundation to bridge between molecular imaging and individual therapy.

Emerging role of positron emission tomography (PET) imaging in cardiac surgery

Historically, structural and anatomical imaging has been the mainstay in the diagnosis and management of cardiovascular diseases. In recent years there has been a shift toward increased use of functional imaging studies, including positron emission tomography (PET). PET is a noninvasive nuclear medicine-imaging technique that uses radiotracers to generate images of a radionucleotide distribution by detecting the physiologic substrates that emit positron radionuclides. This article will focus on the applications of PET imaging for the cardiac surgeon and highlight the collaborative nature of using PET imaging for the management of complex heart disease. We present cases that demonstrate the value of using PET imaging in the diagnosis of coronary artery disease and management of complex endocarditis, and in targeted cardiovascular therapies.

Value of diagnosing immunological phenomena in patients with suspected endocarditis

Purpose

Immunological phenomena are a minor criteria in the modified Duke Criteria for endocarditis. Given the changes in epidemiology and diagnostics, the added value of determining these phenomena in today’s patients with suspected endocarditis is unknown.

Methods

In a retrospective cohort study of all patients with suspected endocarditis admitted to our hospital and discussed in our endocarditis team, we determined the proportion of patients classified as definite endocarditis because of either positive IgM rheumatoid factor (IgM RF), haematuria, or Roth’s spots on ophthalmology consultation. We also determined diagnostic accuracy of each of these immunological phenomena separately and combined.

Results

Of 285 patients included, 138 (48%) had definite endocarditis and at least one immunological test was performed in 222 patients (78%). Elevated IgM RF was found in 22 of 126 patients tested (17%), haematuria in 78 of 196 tested (40%) and Roth’s spots in six of 120 tested (5%). Eighteen of 138 patients with definite IE (13%) were classified as such because of a positive IgM RF, haematuria or Roth’s spots. Haematuria had the highest sensitivity: 50.5% (95% CI 40.4–60.6) and Roth’s spots the highest specificity: 98.3% (95% CI 90.8–99.9). The diagnostic accuracy results were robust in a sensitivity analysis aimed at avoiding incorporation bias.

Conclusion

Among patients with a clinical suspicion of endocarditis, recommended systematic testing for immunological phenomena helped classify more patients as definite IE and is useful to confirm the diagnosis of endocarditis.

Native valve, prosthetic valve, and cardiac device-related infective endocarditis: A review and update on current innovative diagnostic and therapeutic strategies

Infective endocarditis (IE) is a life-threatening microbial infection of native and prosthetic heart valves, endocardial surface, and/or indwelling cardiac device. Prevalence of IE is increasing and mortality has not significantly improved despite technological advances. This review provides an updated overview using recent literature on the clinical presentation, diagnosis, imaging, causative pathogens, treatment, and outcomes in native valve, prosthetic valve, and cardiac device-related IE. In addition, the experimental approaches used in IE research to improve the understanding of disease mechanisms and the current diagnostic pipelines are discussed, as well as potential innovative diagnostic and therapeutic strategies. This will ultimately help towards deriving better diagnostic tools and treatments to improve IE patient outcomes.

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.