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

The Role of 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in the Diagnosis of Left-sided Endocarditis: Native vs Prosthetic Valves Endocarditis

BACKGROUND

18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) has emerged as a useful diagnostic tool for suspected infective endocarditis (IE) in patients with prosthetic valves or implantable devices. However, there is limited evidence regarding use of 18F-FDG-PET/CT for the diagnosis of native valve endocarditis (NVE).

METHODS

Between 2014 and 2017, 303 episodes of left-sided suspected IE (188 prosthetic valves/ascending aortic prosthesis and 115 native valves) were studied. 18F-FDG-PET/CT accuracy was determined in the subgroups of patients with NVE and prosthetic valve endocarditis (PVE)/ascending aortic prosthesis infection (AAPI). Associations between inflammatory infiltrate patterns and 18F-FDG-PET/CT uptake were investigated in an exploratory ad hoc histological analysis.

RESULTS

Among 188 patients with PVE/AAPI, the sensitivity, specificity, and positive and negative predictive values of 18F-FDG-PET/CT focal uptake were 93%, 90%, 89%, and 94%, respectively, while among 115 patients with NVE, the corresponding values were 22%, 100%, 100%, and 66%. The inclusion of abnormal 18F-FDG cardiac uptake as a major criterion at admission enabled a recategorization of 76% (47/62) of PVE/AAPI cases initially classified as "possible" to "definite" IE. In the histopathological analysis, a predominance of polymorphonuclear cell inflammatory infiltrate and a reduced extent of fibrosis were observed in the PVE group only.

CONCLUSIONS

Use of 18F-FDG-PET/CT at the initial presentation of patients with suspected PVE increases the diagnostic capability of the modified Duke criteria. In patients who present with suspected NVE, the use of 18F-FDG-PET/CT is less accurate and could only be considered a complementary diagnostic tool for a specific population of patients with NVE.

State of the art of 18F-FDG PET/CT application in inflammation and infection: a guide for image acquisition and interpretation

AIM

The diagnosis, severity and extent of a sterile inflammation or a septic infection could be challenging since there is not one single test able to achieve an accurate diagnosis. The clinical use of 18F-fluorodeoxyglucose ([¹⁸F]FDG) positron emission tomography/computed tomography (PET/CT) imaging in the assessment of inflammation and infection is increasing worldwide. The purpose of this paper is to achieve an Italian consensus document on [¹⁸F]FDG PET/CT or PET/MRI in inflammatory and infectious diseases, such as osteomyelitis (OM), prosthetic joint infections (PJI), infective endocarditis (IE), prosthetic valve endocarditis (PVE), cardiac implantable electronic device infections (CIEDI), systemic and cardiac sarcoidosis (SS/CS), diabetic foot (DF), fungal infections (FI), tuberculosis (TBC), fever and inflammation of unknown origin (FUO/IUO), pediatric infections (PI), inflammatory bowel diseases (IBD), spine infections (SI), vascular graft infections (VGI), large vessel vasculitis (LVV), retroperitoneal fibrosis (RF) and COVID-19 infections.

METHODS

In September 2020, the inflammatory and infectious diseases focus group (IIFG) of the Italian Association of Nuclear Medicine (AIMN) proposed to realize a procedural paper about the clinical applications of [¹⁸F]FDG PET/CT or PET/MRI in inflammatory and infectious diseases. The project was carried out thanks to the collaboration of 13 Italian nuclear medicine centers, with a consolidate experience in this field. With the endorsement of AIMN, IIFG contacted each center, and the pediatric diseases focus group (PDFC). IIFG provided for each team involved, a draft with essential information regarding the execution of [¹⁸F]FDG PET/CT or PET/MRI scan (i.e., indications, patient preparation, standard or specific acquisition modalities, interpretation criteria, reporting methods, pitfalls and artifacts), by limiting the literature research to the last 20 years. Moreover, some clinical cases were required from each center, to underline the teaching points. Time for the collection of each report was from October to December 2020.

RESULTS

Overall, we summarized 291 scientific papers and guidelines published between 1998 and 2021. Papers were divided in several sub-topics and summarized in the following paragraphs: clinical indications, image interpretation criteria, future perspectivess and new trends (for each single disease), while patient preparation, image acquisition, possible pitfalls and reporting modalities were described afterwards. Moreover, a specific section was dedicated to pediatric and PET/MRI indications. A collection of images was described for each indication.

CONCLUSIONS

Currently, [¹⁸F]FDG PET/CT in oncology is globally accepted and standardized in main diagnostic algorithms for neoplasms. In recent years, the ever-closer collaboration among different European associations has tried to overcome the absence of a standardization also in the field of inflammation and infections. The collaboration of several nuclear medicine centers with a long experience in this field, as well as among different AIMN focus groups represents a further attempt in this direction. We hope that this document will be the basis for a "common nuclear physicians' language" throughout all the country.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40336-021-00445-w.

Prevention and management of endocarditis after transcatheter pulmonary valve replacement: current status and future prospects

Introduction: Transcatheter pulmonary valve replacement (TPVR) has become an important tool in the management of congenital heart disease with abnormalities of the right ventricular outflow tract. Endocarditis is one of the most serious adverse long-term outcomes and among the leading causes of death in patients with congenital heart disease and after (TPVR).Areas covered: This review discusses the current state knowledge about the risk factors for and outcomes of endocarditis after transcatheter pulmonary valve replacement in patients with congenital and acquired heart disease. It also addresses practical measures for mitigating endocarditis risk, as well as diagnosing and managing endocarditis when it does occur.Expert opinion: With increasing understanding of the risk factors for and management and outcomes of endocarditis in patients who have undergone TPVR, we continue to learn how to utilize TPVR most effectively in this complex population of patients.

Diagnosis and Image-guided Therapy of Cardiac Left Ventricular Assist Device Infections

Due to limited availability of donor hearts, more and more end stage heart failure patients are dependent on left ventricular assist device (LVAD) as their destination therapy rather than the original intended use as a bridge for heart transplantation. While LVADs improve life expectancy in these patients, infection emerges as one of the major adverse events. Early and accurate localization of LVAD infection is critical, as it can significantly influence clinical management decisions and ultimately impact patient outcome. Although the International Society of Heart and Lung Transplantation has defined 3 categories for LVAD infection: (1) LVAD-specific infection, (2) LVAD-related infection, and (3) non-LVAD infection, there is still lack of standardized criteria for diagnosing these 3 types of LVAD infections. Morphologically based imaging tools such as transesophageal echocardiogram and cardiac computed tomography (CT) or CT angiogram have limited roles in diagnosing LVAD infections due to their nonspecific findings, often affected by significant streaking and beam hardening artifacts from the metal device. In contrast, ¹⁸F-fluorodeoxyglucose (FDG) Positron Emission Tomography (PET)/CT has repeatedly shown a high sensitivity and specificity for LVAD infection diagnosis, albeit in small number of subjects. Beyond its accuracy for detecting infection, FDG PET/CT can predict clinical outcome based on the location of LVAD infection. As a functional imaging tool, FDG PET/CT can demonstrate the extent and severity of LVAD infection, as well as infectious embolism and potential extra-cardiac source of infection, which are all critical for providing optimal patient care, justifying its judicious and precise use in the workup of LVAD infection.

A narrative review of the interpretation of guidelines for the treatment of infective endocarditis

The recommendations of the current guidelines and the position papers of professional societies from the European Society of Cardiology/European Society of Cardiothoracic Surgeons (ESC), the American College of Cardiology/American Heart Association/Society of Thoracic Surgeon (ACC/AHA/STS) and American Association of Thoracic Surgeon (AATS) regarding management of patients with valvular heart endocarditis were updated over the past decade. However, some of the recommendations appear to contradict one another. Given the changing paradigms on how the disease manifests, our aim was to review the respective guidelines and highlight these differences whilst drawing attention to the subsequent studies from which they were derived. In particular, concerns regarding antibiotic prophylaxis and therapy, imaging modality for diagnosis and follow-up, cerebrovascular sequalae and timing of surgery are appraised in detail. We also identified the novel techniques used such as transcatheter therapies and advances in imaging modalities used for diagnosis and treatment of this condition. The lack of randomised control trials (RCTs) does raise several issues regarding applicability of findings in day-to-day practice. Therefore, the focus of upcoming studies should be on clearly defined multicenter RCTs to provide more robust evidence for the management and treatment of infective endocarditis as future guidelines will be based on the outcomes of these trials.

Feasibility of 18FDG PET in the cardiac inflammation

The aim of the study was to assess the feasibility of ¹⁸FDG PET in cardiac inflammation with a particular focus on the delayed scan. Thirty-five consecutive ¹⁸FDG PET scans of patients with suspected or confirmed cardiac inflammation were retrospectively reviewed. The patients were referred for PET because of endocarditis (n = 16) or sarcoidosis (n = 19). Among them four patients had two consecutive for follow up and treatment control (two patients with sarcoidosis, two with endocarditis). In all of the cases a standard head to mid-thigh scan was performed 45–60 min after ¹⁸FDG injection as well as a delayed heart scan 1 h after the standard imaging was performed. ¹⁸FDG PET confirmed active inflammation in 10 out of 35 scans. Delayed scans in positive cases showed SUVmax value increase, but did not have an impact on the result, neither they did in negative cases—no significant differences between standard and delayed scan were found. Interestingly in 5 out of 14 cases with suspected endocarditis PET revealed the extracardiac inflammation focus, thus changing initial diagnosis. ¹⁸FDG PET also indicated which prosthesis caused inflammation if there were many. In the sarcoidosis group the aim was to confirm or exclude heart involvement (13 scans) or to assess the response to the steroid therapy (6 scans) in patients with previously confirmed sarcoidosis. PET revealed active heart disease in 3 initial scans, and 1 follow up scan. ¹⁸FDG PET is a valuable imaging method for the cardiac inflammation assessment. It adequately localises the active inflammation site. Also, since it is a whole-body scan it may detect the extracardiac inflammation foci, which in some cases may change the initial diagnosis. In our study the delayed scans showed no added value.

F-18 fluorodeoxyglucose positron emission tomography/computed tomography in the infection of heart

Infections involving the heart are becoming increasingly common, and a timely diagnosis of utmost importance, despite its challenges. F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is a recently introduced diagnostic tool in cardiology. This review focuses on the current evidence for the use of FDG PET/CT in the diagnosis of infective endocarditis, cardiac implantable device infection, left ventricular assist device infection, and secondary complications. The author discusses considerations when using FDG PET/CT in routine clinical practice, patient preparation for reducing physiologic myocardial uptake, acquisition of images, and interpretation of PET/CT findings. This review also functions to highlight the need for a standardized acquisition protocol.

Temporal changes in the incidence of infective endocarditis in Denmark 1997-2017: A nationwide study

BACKGROUND

Infective endocarditis (IE) remains a life-threatening disease, yet substantial variation in reported incidences of the disease exist. We aimed to conduct a contemporary, nationwide study of the temporal changes in incidence of IE.

METHODS

We included all Danish cases of first-time IE (1997-2017) using nationwide registries. Patients were grouped into three seven-year intervals (1997-2003, 2004-2010, 2011-2017). Crude annual incidence rates (IR) per 100,000 person-years (PY) were examined overall and per subgroups: age, sex, patients without prior prosthetic heart valve or a cardiac implantable electronic device (CIED). Incidence rate ratios (IRR) were calculated adjusting for age-group, sex and diabetes.

RESULTS

We identified 8675 patients with IE. Over time, patients were older at diagnosis with a median age of 66.2 years (interquartile range, IQR: 51.5-76.5) and 72.2 years (IQR 62.2-79.9) in 1997-2003 and 2011-2017, respectively. The overall IR increased from 5.0/100,000 PY (95% CI: 4.4-5.6) to 10.5/100,000 PY (95% CI: 9.6-11.3) from 1997 to 2017. IR for patients without prior prosthetic heart valve or a CIED increased from 4.9/100,000 PY (95% CI: 4.3-5.5) to 6.4/100,000 PY (95% CI: 5.8-7.1) (P ≤ 0.0001 for interaction). The IR in males increased from 5.6/100,000 PY (95% CI: 4.7-6.5) to 14.2/100,000 PY (95% CI: 12.9-15.6). The IR in females increased from 4.3/100,000 PY (95% CI: 3.6-5.2) to 6.7/100,000 PY (95% CI: 5.8-7.7). IRR (adjusted for age-groups, sex and diabetes) increased over time (IRR = 1.60 (1.39-1.85) in 2017 vs 1997).

CONCLUSION

The incidence of IE more than doubled during the study period. The increase was mainly seen among men and elderly patients only partly explained by the increase in patients with prior heart valve prosthesis or a CIED.

Clinical presentation, aetiology and outcome of infective endocarditis. Results of the ESC-EORP EURO-ENDO (European infective endocarditis) registry: a prospective cohort study

AIMS

The EURO-ENDO registry aimed to study the management and outcomes of patients with infective endocarditis (IE).

METHODS AND RESULTS

Prospective cohort of 3116 adult patients (2470 from Europe, 646 from non-ESC countries), admitted to 156 hospitals in 40 countries between January 2016 and March 2018 with a diagnosis of IE based on ESC 2015 diagnostic criteria. Clinical, biological, microbiological, and imaging [echocardiography, computed tomography (CT) scan, 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT)] data were collected. Infective endocarditis was native (NVE) in 1764 (56.6%) patients, prosthetic (PVIE) in 939 (30.1%), and device-related (CDRIE) in 308 (9.9%). Infective endocarditis was community-acquired in 2046 (65.66%) patients. Microorganisms involved were staphylococci in 1085 (44.1%) patients, oral streptococci in 304 (12.3%), enterococci in 390 (15.8%), and Streptococcus gallolyticus in 162 (6.6%). 18F-fluorodeoxyglucose positron emission tomography/computed tomography was performed in 518 (16.6%) patients and presented with cardiac uptake (major criterion) in 222 (42.9%) patients, with a better sensitivity in PVIE (66.8%) than in NVE (28.0%) and CDRIE (16.3%). Embolic events occurred in 20.6% of patients, and were significantly associated with tricuspid or pulmonary IE, presence of a vegetation and Staphylococcus aureus IE. According to ESC guidelines, cardiac surgery was indicated in 2160 (69.3%) patients, but finally performed in only 1596 (73.9%) of them. In-hospital death occurred in 532 (17.1%) patients and was more frequent in PVIE. Independent predictors of mortality were Charlson index, creatinine > 2 mg/dL, congestive heart failure, vegetation length > 10 mm, cerebral complications, abscess, and failure to undertake surgery when indicated.

CONCLUSION

Infective endocarditis is still a life-threatening disease with frequent lethal outcome despite profound changes in its clinical, microbiological, imaging, and therapeutic profiles.

Diagnostic Performance of 18F-FDG PET/CT in Native Valve Endocarditis: Systematic Review and Bivariate Meta-Analysis

BACKGROUND

Infectious endocarditis is a life-threatening disease, requiring prompt and accurate diagnosis. The aim of this article is to perform a systematic review and meta-analysis of the literature to estimate the performance of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) for the diagnosis of native valve endocarditis (NVE).

METHODS

Selected articles evaluating the diagnostic accuracy of 18F-FDG PET/CT in patients with suspected NVE, resulting from a comprehensive literature search through the PubMed/MEDLINE and Cochrane library databases until April 2020, were included for the systematic review and meta-analysis.

RESULTS

Seven studies (351 episodes of suspected NVE) were included. 18F-FDG PET/CT yielded a pooled sensitivity of 36.3% and a pooled specificity of 99.1% for the diagnosis of NVE. The pooled positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 8.3, 0.6, and 15.3, respectively. The sensitivity increased using contemporary PET/CT device with state-of-the-art patient preparation as well as innovative image acquisitions or adding the results of 18F-FDG PET/CT in a multimodality strategy.

CONCLUSIONS

In our systematic review and meta-analysis, 18F-FDG PET/CT yielded a poor pooled sensitivity with an otherwise excellent pooled specificity for the diagnosis of NVE; however, several factors may increase the sensitivity without affecting the specificity and these factors should be better evaluated in future studies.

Risk-benefit Assessment of Systematic Thoracoabdominal-pelvic Computed Tomography in Infective Endocarditis

BACKGROUND

In the management of infective endocarditis (IE), the presence of extracardiac complications has an influence on both diagnosis and treatment. Current guidelines suggest that systematic thoracoabdominal-pelvic computed tomography (TAP-CT) may be helpful. Our objective was to describe how systematic TAP-CT affects the diagnosis and the management of IE.

METHODS

In this multicenter cohort study, between January 2013 and July 2016 we included consecutive patients who had definite or possible IE according to the Duke modified criteria, validated by endocarditis teams. We analyzed whether the Duke classification and therapeutic management were modified regarding the presence or the absence of IE-related lesion on CT and investigated the tolerance of this examination.

RESULTS

Of the 522 patients included in this study, 217 (41.6%) had 1 or more IE-related lesions. On the basis of CT results in asymptomatic patients, diagnostic classification was upgraded from possible endocarditis to definite endocarditis for only 4 cases (0.8%). The presence of IE-related lesions on CT did not modify the duration of antibiotic treatment (P = .55), nor the decision of surgical treatment (P = .39). Specific treatment of the lesion was necessary in 42 patients (8.0%), but only 9 of these lesions (1.9%) were asymptomatic and diagnosed only on the TAP-CT. Acute kidney injury (AKI) within 5 days of CT was observed in 78 patients (14.9%).

CONCLUSIONS

The TAP-CT findings slightly affected diagnosis and treatment of IE in a very small proportion of asymptomatic patients. Furthermore, contrast media should be used with caution because of the high risk of AKI.

Fluorodeoxyglucose Applications in Cardiac PET: Viability, Inflammation, Infection, and Beyond

With its high temporal and spatial resolution and relatively low radiation exposure, positron emission tomography (PET) is increasingly being used in the management of cardiac patients, particularly those with inflammatory cardiomyopathies such as sarcoidosis. This review discusses the role of PET imaging in assessing myocardial viability, inflammatory cardiomyopathies, and endocarditis; describes the different protocols needed to acquire images for specific imaging tests; and examines imaging interpretation for each image dataset-including identification of the mismatch defect in viability imaging, which is associated with significant improvement in LV function after revascularization. We also review the role of fluorodeoxyglucose PET in cardiac sarcoidosis diagnosis, the complementary role of magnetic resonance imaging in inflammatory cardiomyopathy, and the emerging use of cardiac PET in prosthetic valve endocarditis.

Fever without a source in children with congenital heart disease

Two paediatric congenital heart disease patients presented with a brief history of low-grade fever without any focal symptoms. Their clinical features and laboratory tests were unremarkable; however, their blood cultures were positive that prompted further work-up. Infective endocarditis should be considered in any paediatric congenital heart disease patient who presents with fever without any other associated clinical features.

Infective Endocarditis After Surgical and Transcatheter Aortic Valve Replacement: A State of the Art Review

Prosthetic valve endocarditis (PVE) after surgical aortic valve replacement and transcatheter aortic valve replacement (TAVR) carries significant morbidity/mortality. Our review aims to compare incidence, predisposing factors, microbiology, diagnosis, management, and outcomes of PVE in surgical aortic valve replacement/TAVR patients. We searched PubMed and Embase to identify published studies from January 1, 2015 to March 13, 2020. Key words were indexed for original reports, clinical studies, and reviews. Reports were evaluated by 2 authors against a priori inclusion/exclusion criteria. Studies were included if they reported incidence and outcomes related to surgical aortic valve replacement/TAVR PVE and excluded if they were published pre-2015 or included a small population. We followed the Cochrane methodology and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for all stages of the design and implementation. Study quality was based on the Newcastle-Ottawa Scale. Thirty-three studies with 311 to 41 025 patients contained relevant information. The majority found no significant difference in incidence of surgical aortic valve replacement/TAVR PVE (reported as 0.3%-1.2% per patient-year versus 0.6%-3.4%), but there were key differences in pathogenesis. TAVR has a specific set of infection risks related to entry site, procedure, and device, including nonstandardized protocols for infection control, valve crimping injury, paravalvular leak, neo-leaflet stress, intact/calcified native leaflets, and intracardiac hardware. With the expansion of TAVR to lower risk and younger patients, a better understanding of pathogenesis, patient presentation, and guideline-directed treatment is paramount. When operative intervention is necessary, mortality remains high at 20% to 30%. Unique TAVR infection risks present opportunities for PVE prevention, therefore, further investigation is imperative.

Detachment of a prosthetic valve due to infective endocarditis caused by Streptococcus pneumoniae

The incidence of infective endocarditis (IE) due to S pneumoniae has decreased, thanks to antibiotics. However, when it does occur, it can be lethal. The present case provides a reminder of the potential lethality of this postoperative infection.

Usefulness of 18F-FDG PET/CT in Patients with Cardiac Implantable Electronic Device Suspected of Late Infection

The presence of a cardiovascular implantable electronic device (CIED) can be burdened by complications such as late infections that are associated with significant morbidity and mortality and require immediate and effective treatment. The aim of this study was to evaluate the role of ¹⁸F-fluorodeoxyglucose positron-emission tomography/computed tomography (¹⁸F-FDG PET/CT) in patients with suspected CIED infection. Fifteen patients who performed a ¹⁸F-FDG PET/CT for suspicion of CIED infection were retrospectively analyzed; 15 patients, with CIED, that underwent ¹⁸F-FDG PET/CT for oncological reasons, were also evaluated. Visual qualitative analysis and semi-quantitative analysis were performed. All patients underwent standard clinical management regardless ¹⁸F-FDG PET/CT results. Sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) resulted as 90.91%, 75%, 86.67%, 90.91% and 75% respectively. Maximum standardized uptake values (SUV_max) and semi-quantitative ratio (SQR) were collected and showed differences statistically significant between CIED infected patients and those who were not. Exploratory cut-off values were derived from receiver operating characteristic (ROC) curves for SUV_max (2.56) and SQR (4.15). This study suggests the clinical usefulness of ¹⁸F-FDG PET/CT in patients with CIED infection due to its high sensitivity, repeatability and non-invasiveness. It can help the clinicians in decision making, especially in patients with doubtful clinical presentation. Future large-scale and multicentric studies should be conducted to establish precise protocols about ¹⁸F-FDG PET/CT performance.

Detection of Native and Prosthetic Valve Endocarditis: Incremental Attributes of Functional FDG PET/CT over Morphologic Imaging

PURPOSE OF REVIEW

The clinical and incremental value of functional imaging with ¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG PET/CT) for the diagnosis and management of patients with suspected native and prosthetic valve infective endocarditis (IE).

RECENT FINDINGS

The diagnosis of IE is challenging because of the highly variable clinical presentations, especially in the case of prosthetic valve endocarditis (PVE). FDG PET/CT has been shown to play an important role for the diagnosis of PVE as a major Duke criterion. Whether FDG PET/CT could play a similar role in patients with suspected native valve endocarditis (NVE) is less well established. It is increasingly recognized that IE is a multisystem disorder, and identification of extra-cardiac manifestations on whole-body FDG PET/CT impacts management and prognosis of patients with IE. Finally, FDG PET/CT provides incremental prognostic value over other clinical and para-clinical parameters, enabling prediction of in-hospital mortality, IE recurrence, hospitalization, and new onset heart failure and embolic events. FDG PET/CT plays a key role in the investigation of patients with suspected IE, enabling detection of valvular infection and extra-cardiac manifestations of the infection which has important prognostic implications.

Optimizing outcomes in infective endocarditis: A comprehensive literature review

BACKGROUND

Despite being rare, infective endocarditis (IE) is a life-threatening disease with poor prognosis. New diagnostic and therapeutic strategies are emerging; however, predisposing factors and microbiology of the disease are also changing with time. Because of this, there has been a lack of reduction in the disease's incidence and new challenges for clinicians have arisen such as an increasingly aging population and growing antimicrobial resistance.

AIMS

In this paper, we aim to provide an overview of the changing trends in IE, current diagnosis, and management strategies, as well as the emerging role of the infective endocarditis teams in the care of patients with this disease.

MATERIALS & METHODS

A comprehensive electronic search was done utilizing PubMed, Ovid, SCOPUS, Embase and google scholar. The search terms included 'Endocarditis', 'IE', 'Infection', 'Vegetation', 'Duke criteria', 'native valve infection', 'prosthetic valve', 'valve infection', 'endocarditis outcome' and 'endocarditis bacteriology'. The references of the identified articles were then searched for any potential articles that can be included. The inclusion criteria were any article that discussed the evidence behind incidence and management of IE including the role of endocarditis team. The exclusion criteria were case reports, expert opinion, and editorials.

RESULTS

All the relevant findings are summarized in specified tables and within appropriate sections.

DISCUSSION

It is vital to determine the current trends in the epidemiology and microbiology of the condition so that the diagnostic threshold can be adapted, to identify new at-risk groups and achieve an accelerated evaluation strategy that allows for earlier diagnosis and treatment.

CONCLUSION

Management of IE can benefit from the input of different specialties, such as cardiology, cardiothoracic surgery, infectious disease, and microbiology. Therefore, adopting a multidisciplinary approach towards treatment is crucial to reduce morbidity and mortality from preventable complications of this pathology.

Comparison Between ESC and Duke Criteria for the Diagnosis of Prosthetic Valve Infective Endocarditis

OBJECTIVES

The primary objective was to assess the value of the European Society of Cardiology (ESC) criteria, including ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT) in prosthetic valve infective endocarditis (PVE). Secondary objectives were: 1) to assess the reproducibility of ¹⁸F-FDG-PET/CT; 2) to compare its diagnostic value with that of echocardiography; and 3) to assess the diagnostic value of the presence of a diffuse splenic uptake BACKGROUND: ¹⁸F-FDG PET/CT has been added as a major criterion in the ESC 2015 infective endocarditis (IE) guidelines, but the benefit of the ESC criteria has not been prospectively compared with the conventional Duke criteria.

METHODS

Between 2014 and 2017, 175 patients with suspected PVE were prospectively included in 3 French centers. After exclusion of patients with uninterpretable ¹⁸F-FDG PET/CT, 115 patients were evaluated, including 91 definite and 24 rejected IE, as defined by an expert consensus.

RESULTS

Cardiac uptake by ¹⁸F-FDG PET/CT was observed in 67 of 91 patients with definite PVE and 6 with rejected IE (sensitivity 73.6% [95% confidence interval (CI): 63.3% to 82.3%], specificity 75% [95% CI: 53.3% to 90.2%]). The ESC 2015 classification increased the sensitivity of Duke criteria from 57.1% (95% CI: 46.3% to 67.5%) to 83.5% (95% CI: 74.3% to 90.5%) (p < 0.001), but decreased its specificity from 95.8% (95% CI: 78.9% to 99.9%) to 70.8% (95% CI: 48.9% to 87.4%). Intraobserver reproducibility of ¹⁸F-FDG PET/CT was good (kappa = 0.84) but interobserver reproducibility was less satisfactory (kappa = 0.63). A diffuse splenic uptake was observed in 24 (20.3%) patients, including 23 (25.3%) of definite PVE, and only 1 (4.2%) rejected PVE (p = 0.024).

CONCLUSIONS

¹⁸F-FDG PET/CT is a useful diagnostic tool in suspected PVE, and explains the greater sensitivity of ESC criteria than Duke criteria. However, ¹⁸F-FDG PET/CT also presents with important limitations concerning its feasibility, specificity, and reproducibility. Our study describes for the first time a new endocarditis criterion, that is, the presence of a diffuse splenic uptake on ¹⁸F-FDG PET/CT.

Diagnostic imaging in infective endocarditis: a contemporary perspective

INTRODUCTION

Infective endocarditis (IE) remains a diagnostic challenge. Prompt diagnosis is essential for accurate risk stratification and appropriate therapeutic decisions and surgical management. In recent years, the use of multimodal imaging has had a transformative effect on the diagnostic approach of IE in selected patients.

AREAS COVERED

This review assesses published literature on different imaging modalities for the diagnosis of IE published between 1 January 2009 and 1 February 2020. We illustrate the diagnostic approach to IE with three clinical cases.

EXPERT OPINION

Novel approaches to imaging for cardiac and extracardiac complications improve and individualize diagnosis, management, and prognosis in patients with suspected IE. The use of multimodal imaging should be guided by a multidisciplinary group of medical providers that includes infectious disease specialists, radiologists, cardiologists, and cardiothoracic surgeons.

Diagnosis of Infective Endocarditis by Subtype Using 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography: A Contemporary Meta-Analysis

Background Infective endocarditis (IE) remains a difficult to diagnose condition associated with high mortality. ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) has recently emerged as another IE imaging modality, although diagnostic accuracy varies across observational studies and types of IE. This meta-analysis assessed the diagnostic performance of ¹⁸F-FDG PET/CT for IE and its subtypes. Methods We searched Pubmed, Cochrane, and Embase from January 1980 to September 2019 for studies reporting both sensitivity and specificity of ¹⁸F-FDG PET/CT for IE. Meta-Disc 1.4 was used to pool data for all cases of IE and its subgroups of native valve IE, prosthetic valve IE, and cardiac implantable electronic devices IE. Results We screened 2566 records from the search, assessed 52 full-text articles, and included 26 studies totaling 1358 patients (509 IE cases). Pooled sensitivity and specificity (95% CI, inconsistency I-square statistic) were 0.74 (0.70-0.77, 71.5%) and 0.88 (0.86-0.91, 78.5%) for all cases of endocarditis. Corresponding parameters for native valve IE were sensitivity 0.31 (0.21-0.41, 29.4%) and specificity 0.98 (0.95-0.99, 34.4%); for prosthetic valve IE: sensitivity 0.86 (0.81-0.89, 60.0%) and specificity 0.84 (0.79-0.88, 75.2%); and for cardiac implantable electronic devices IE: sensitivity 0.72 (0.61-0.81, 76.2%) and specificity 0.83 (0.75-0.89, 83.6%). Pooled sensitivities and specificities were higher for the 17 studies since 2015 than the 9 studies published before 2015. Conclusions ¹⁸F-FDG PET/CT had high specificity for all IE subtypes; however, sensitivity was markedly lower for native valve IE than prosthetic valve IE and cardiac implantable electronic devices IE. It is, therefore, a useful adjunct modality for assessing endocarditis, especially in the challenging scenarios of prosthetic valve IE and cardiac implantable electronic devices IE, with improving performance over time, related to advances in ¹⁸F-FDG PET/CT techniques.

Infective endocarditis in the Netherlands: current epidemiological profile and mortality : An analysis based on partial ESC EORP collected data

Introduction

Infective endocarditis (IE) is associated with a high in-hospital and long term mortality. Although progress has been made in diagnostic approach and management of IE, morbidity and mortality of IE remain high. In the latest European guidelines, the importance of the multi-modality imaging in diagnosis and follow up of IE is emphasized.

Aim

The aim was to provide information regarding mortality and adverse events of IE, to determine IE characteristics and to assess current use of imaging in the diagnostic workup of IE.

Methods

This is a prospective observational cohort study. We used data from the EURO-ENDO registry. Seven hospitals in the Netherlands have participated and included patients with IE between April 2016 and April 2018.

Results

A total of 139 IE patients were included. Prosthetic valve endocarditis constituted 32.4% of the cases, cardiac device related IE 7.2% and aortic root prosthesis IE 3.6%. In-hospital mortality was 14.4% (20 patients) and one-year mortality was 21.6% (30 patients). The incidence of embolic events under treatment was 16.5%, while congestive heart failure or cardiogenic shock occurred in 15.1% of the patients. Transthoracic and transoesophageal echocardiography were performed most frequently (97.8%; 81.3%) and within 3 days after IE suspicion, followed by ¹⁸F‑fluorodeoxyglucose positron emission tomography/computed tomography (45.3%) within 6 days and multi-slice computed tomography (42.4%) within 7 days.

Conclusion

We observed a high percentage of prosthetic valve endocarditis, rapid and extensive use of imaging and a relatively low in-hospital and one-year mortality of IE in the Netherlands. Limitations include possible selection bias.

Electronic supplementary material

The online version of this article (10.1007/s12471-020-01431-z) contains supplementary material, which is available to authorized users. A complete list of the EURO-ENDO Investigators Group and of the EURO-ENDO National Coordinators is provided in the ESM.

Clinical outcomes for congenital heart disease patients presenting with infective endocarditis

INTRODUCTION

Infective endocarditis (IE) is a life-threatening adverse event for patients with congenital heart disease (CHD). Its incidence has changed little over time despite progress in techniques for diagnosis and treatment, and guidelines for prophylaxis.

AREAS COVERED

The review sought for key-words: 'congenital heart disease,' 'infective endocarditis,' 'microbial diagnosis,' 'imaging diagnosis,' 'surgical techniques,' 'prognosis,' 'prophylaxis.' Objectives were to investigate epidemiology, novel techniques for imaging and microbial diagnosis, therapeutic management and prognosis, and guidelines for prophylaxis in patients with CHD. The incidence of IE is increasing in adults with CHD. Morbidity caused by a broad clinical spectrum of cardiac and extracardiac episode-related complications is high. Surgical management is increasingly required in the early phase of the disease. Despite new techniques for diagnosis and microbiological therapy, mortality rate is still up to 10-20%.

EXPERT OPINION

IE has increased in the growing cohort of adults with complex heart disease, living with residual cardiac lesions and prosthetic materials. Diagnosis is challenging for complex heart defects. Pet-scan technique can provide beneficial information to locate intracardiac lesions and embolic foci. Identification of the microbiological agents is improving. Innovative surgical techniques aim to avoid prosthetic material. Guidelines for prophylaxis currently emphasize oral and skin daily hygiene.

Prevalence of Infective Endocarditis in Enterococcus faecalis Bacteremia

BACKGROUND

Enterococcus faecalis is the third most frequent cause of infective endocarditis (IE). Despite this, no systematic prospective echocardiography studies have examined the prevalence of IE in patients with E. faecalis bacteremia.

OBJECTIVES

This study sought to determine the prevalence of IE in patients with E. faecalis bacteremia. The secondary objective was to identify predictors of IE.

METHODS

From January 1, 2014, to December 31, 2016, a prospective multicenter study was conducted with echocardiography in consecutive patients with E. faecalis bacteremia. Predictors of IE were assessed using multivariate logistic regression with backward elimination.

RESULTS

A total of 344 patients with E. faecalis bacteremia were included, all examined using echocardiography, including transesophageal echocardiography in 74% of the cases. The patients had a mean age of 74.2 years, and 73.5% were men. Definite endocarditis was diagnosed in 90 patients, resulting in a prevalence of 26.1 ± 4.6% (95% confidence interval [CI]). Risk factors for IE were prosthetic heart valve (odds ratio [OR]: 3.93; 95% CI: 1.76 to 8.77; p = 0.001), community acquisition (OR: 3.35; 95% CI: 1.74 to 6.46; p < 0.001), ≥3 positive blood culture bottles (OR: 3.69; 95% CI: 1.88 to 7.23; p < 0.001), unknown portal of entry (OR: 2.36; 95% CI: 1.26 to 4.40; p = 0.007), monomicrobial bacteremia (OR: 2.73; 95% CI: 1.23 to 6.05; p = 0.013), and immunosuppression (OR: 2.82; 95% CI: 1.20 to 6.58; p = 0.017).

CONCLUSIONS

This study revealed a high prevalence of 26% definite IE in patients with E. faecalis bacteremia, suggesting that echocardiography should be considered in all patients with E. faecalis bacteremia.

Subacute pericardial abscess after aortic valve replacement: a case report

Background

Purulent pericarditis is an infectious disease, frequently caused by gram-positive bacteria, that is rarely observed in healthy individuals, and is often associated with predisposing conditions.

Case presentation

Here, we present the case of an Escherichia coli post-surgical localized purulent pericarditis complicated by transient constrictive pericarditis and its diagnostic and therapeutic management.

Conclusions

Our case report focuses on the importance of imaging-guided treatment of purulent pericardial diseases, in particular on the emerging role of 18 F-labelled 2-fluoro-2-deoxy-D-glucose Positron Emission Tomography/Computed Tomography in pericardial diseases and on the management of transient constrictive pericarditis, often seen after thoracic surgery.

Infective Endocarditis: A Contemporary Review

Infective endocarditis (IE), initially described more than 350 years ago, involves infection of the endocardial surface of the heart. The clinical manifestations of IE can involve every organ system, and the cardiac manifestations can include valvular vegetation, abscess, periannular extension of infection, and myopericarditis. Echocardiography is crucial in the diagnosis of IE, but alternative imaging modalities are playing an increasing role in the diagnosis and management of IE. Multidisciplinary care is imperative to the management of IE, often requiring the expertise of cardiologists, cardiothoracic surgeons, infectious diseases specialists, radiologists, and neurologists. We performed a literature search of the PubMed database from January 1st, 2000, to September 30th, 2019, using the terms infective endocarditis, diagnosis, and management to find the most pertinent and highest-quality evidence. This review summarizes key aspects of IE, with a focus on emerging advances in diagnosis. We also highlight growing patient populations at risk for IE, including patients with intracardiac devices and congenital heart disease.

Imaging infective endocarditis: Adherence to a diagnostic flowchart and direct comparison of imaging techniques

BACKGROUND

Multimodality imaging is recommended to diagnose infective endocarditis. Value of additional imaging to echocardiography in patients selected by a previously proposed flowchart has not been evaluated.

METHODS

An observational single-center study was performed. Adult patients suspected of endocarditis/device infection were prospectively and consecutively enrolled from March 2016 to August 2017. Adherence to a diagnostic imaging-in-endocarditis-flowchart was evaluated in 176 patients. Imaging techniques were compared head-to-head in 46 patients receiving echocardiography (transthoracic plus transesophageal), multi-detector computed tomography angiography (MDCTA), and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET/CT).

RESULTS

69% of patients (121/176) adhered to the flowchart. Sensitivity of echocardiography, MDCTA, FDG-PET/CT in patients without prosthesis was 71%, 57%, 29% (86% when combined), while specificity was 100%, 75%, 100%, respectively. Sensitivity in patients with prosthesis was 75%, 75%, 83%, respectively (100% when combined), while specificity was 86% for all three modalities. Echocardiography performed best in the assessment of vegetations, morphological valve abnormalities/dehiscence, septum defects, and fistula formation. MDCTA performed best in the assessment of abscesses and ventricular assist device infection. FDG-PET/CT performed best in the assessment of cardiac device infection, extracardiac infectious foci, and alternative diagnoses.

CONCLUSIONS

This study demonstrates that the evaluated imaging-in-endocarditis-flowchart is applicable in daily clinical practice. Echocardiography, MDCTA, and FDG-PET/CT provide relevant complementary diagnostic information, particularly in patients with intracardiac prosthetic material.

Pulmonary Valve Endocarditis: The Potential Utility of Multimodal Imaging Prior to Surgery

BACKGROUND

The presence of echocardiographic (echo) evidence is a major criterion for the diagnosis of infective endocarditis (IE) by modified Duke criteria. Pulmonary valve (PV) IE, however, can be challenging to identify by echo. We sought to evaluate the added utility of multimodal imaging in PV IE.

METHODS

This is a single-center case series. We retrospectively analyzed demographic, laboratory, imaging, clinical, and surgical data from patients diagnosed with PV IE from 2008 to 2018.

RESULTS

A total of 23 patients were identified with definite PV IE by Duke criteria (83% male and ages 2 months to 70 years). Twenty-two patients had congenital heart disease, with 21 involving the right ventricular outflow tract (including three with transcatheter PV implant). Overall, 20 (87%) of 23 had positive blood cultures. A total of 17 (74%) of 23 patients demonstrated echo evidence of PV IE. In three cases, echo was negative (did not show vegetations) but showed new PV obstruction. In four cases with negative transthoracic echocardiogram and transesophageal echocardiogram, evidence of PV IE was subsequently seen by positron emission tomography/computed tomography (n = 2) or cardiac magnetic resonance imaging (n = 2). Pulmonary valve IE was confirmed at surgery by evaluation of pathologic samples in 20 cases.

CONCLUSIONS

Multimodal imaging improves the ability to preoperatively identify endocardial involvement in PV IE in cases where echo is negative. Consideration should be given to revise Duke criteria to include new obstruction and endocardial involvement by multimodal imaging for PV IE.

Rapidly expanding saphenous vein graft myoctic aneurysm causing ST-elevation myocardial infarction: a case report

Background 

Mycotic aneurysms of coronary vein grafts are rare and associated with high mortality. They are most commonly a result of surgical or percutaneous intervention, and present with complications including myocardial infarction (MI), infective endocarditis. A recent literature review identified 97 cases of mycotic coronary aneurysms in total.

Case summary

A 49-year-old man with a history of coronary artery bypass grafting and septic arthrithis presented with chest pain and fevers and ST elevation on electrocardiogram. Urgent angiogram showed an aneurysmal saphenous vein graft from the PL branch to PDA-no acute intervention was performed due to concern about bacteraemia. Methicillin-sensitive Staphylococcus aureus was grown in urine and blood but no focus of infection was identified. Despite treatment with antibiotics and antiplatelets, the patient returned with evidence of expansion of the SVG aneurysm requiring surgical resection.

Discussion 

This case highlights the difficulty in treating acute coronary syndromes involving mycotic aneurysms. Multimodal imaging approaches are useful to identify suspected infection, but false negatives occur. Due to high risk of rupture or haemorrhage, there are limited options for urgent reperfusion in cases of MI with mycotic aneurysm, demonstrating the need for an individualized approach and close follow-up.

Higher incidence of perivalvular abscess determines perioperative clinical outcome in patients undergoing surgery for prosthetic valve endocarditis

Background

Cardiac surgery for prosthetic valve endocarditis (PVE) is associated with substantial mortality. We aimed to analyze 30-day and 1-year outcome in patients undergoing surgery for PVE and sought to identify preoperative risk factors for mortality with special regard to perivalvular infection.

Methods

We retrospectively analyzed data of 418 patients undergoing valve surgery for infective endocarditis between January 2009 and July 2018. After 1:1 propensity matching 158 patients (79 PVE/79 NVE) were analyzed with regard to postoperative 30-day and 1-year outcomes. Univariate and multivariable analyses were performed to identify potential risk factors for mortality.

Results

315 patients (75.4%) underwent surgery for NVE and 103 (24.6%) for PVE. After propensity matching groups were comparable with regard to preoperative characteristics, clinical presentation and microbiological findings, except a higher incidence of perivalvular infection in patients with PVE (51.9%) compared to NVE (26.6%) (p = 0.001), longer cardiopulmonary bypass (166 [76–130] vs. 97 [71–125] min; p < 0.001) and crossclamp time (95 [71–125] vs. 68 [55–85] min; p < 0.001). Matched patients with PVE showed a 4-fold increased 30-day mortality (20.3%) in comparison with NVE patients (5.1%) (p = 0.004) and 2-fold increased 1-year mortality (PVE 29.1% vs. NVE 13.9%; p = 0.020). Multivariable analysis revealed perivalvular abscess, sepsis, preoperative AKI and PVE as independent risk factors for mortality. Patients with perivalvular abscess had a significantly higher 30-day mortality (17.7%) compared to patients without perivalvular abscess (8.0%) (p = 0.003) and a higher rate of perioperative complications (need for postoperative pacemaker implantation, postoperative cerebrovascular events, postoperative AKI). However, perivalvular abscess did not influence 1-year mortality (20.9% vs. 22.3%; p = 0.806), or long-term complications such as readmission rate or relapse of IE.

Conclusions

Patients undergoing surgery for PVE had a significantly higher 30-day and 1-year mortality compared to NVE. After propensity-matching 30-day mortality was still 4-fold increased in PVE compared to NVE.

Patients with perivalvular abscess showed a significantly higher 30-day mortality and perioperative complications, whereas perivalvular abscess seems to have no relevant impact on 1-year mortality, the rate of readmission or relapse of IE.

Infective endocarditis: innovations in the management of an old disease

The annual incidence of infective endocarditis (IE) is estimated to be between 15 and 80 cases per million persons in population-based studies. The incidence of IE is markedly increased in patients with valve prostheses (>4 per 1,000) or with prior IE (>10 per 1,000). The interaction between platelets, microorganisms and diseased valvular endothelium is the cause of vegetations and valvular or perivalvular tissue destruction. Owing to its complexity, the diagnosis of IE is facilitated by the use of the standardized Duke-Li classification, which combines two major criteria (microbiology and imaging) with five minor criteria. However, the sensitivity of the Duke-Li classification is suboptimal, particularly in prosthetic IE, and can be improved by the use of PET or radiolabelled leukocyte scintigraphy. Prolonged antibiotic therapy is mandatory. Indications for surgery during acute IE depend on the presence of haemodynamic, septic and embolic complications. The most urgent indications for surgery are related to heart failure. In the past decade, the prevention of IE has been reoriented, with indications for antibiotic prophylaxis now limited to patients at high risk of IE undergoing dental procedures. Guidelines now emphasize the importance of nonspecific oral and cutaneous hygiene in individual patients and during health-care procedures.

Clinical Practice Update on Infectious Endocarditis

Infectious endocarditis is a highly morbid disease with approximately 43,000 cases per year in the United States. The modified Duke Criteria have poor sensitivity; however, advances in diagnostic imaging provide new tools for clinicians to make what can be an elusive diagnosis. There are a number of risk stratification calculators that can help guide providers in medical and surgical management. Patients who inject drugs pose unique challenges for the health care system as their addiction, which is often untreated, can lead to recurrent infections after valve replacement. There is a need to increase access to medication-assisted treatment for opioid use disorders in this population. Recent studies suggest that oral and depo antibiotics may be viable alternatives to conventional intravenous therapy. Additionally, shorter courses of antibiotic therapy are potentially equally efficacious in patients who are surgically managed. Given the complexities involved with their care, patients with endocarditis are best managed by multidisciplinary teams.

Assessing the interactions between radiotherapy and antitumour immunity

Immunotherapy, specifically the introduction of immune checkpoint inhibitors, has transformed the treatment of cancer, enabling long-term tumour control even in individuals with advanced-stage disease. Unfortunately, only a small subset of patients show a response to currently available immunotherapies. Despite a growing consensus that combining immune checkpoint inhibitors with radiotherapy can increase response rates, this approach might be limited by the development of persistent radiation-induced immunosuppression. The ultimate goal of combining immunotherapy with radiotherapy is to induce a shift from an ineffective, pre-existing immune response to a long-lasting, therapy-induced immune response at all sites of disease. To achieve this goal and enable the adaptation and monitoring of individualized treatment approaches, assessment of the dynamic changes in the immune system at the patient level is essential. In this Review, we summarize the available clinical data, including forthcoming methods to assess the immune response to radiotherapy at the patient level, ranging from serum biomarkers to imaging techniques that enable investigation of immune cell dynamics in patients. Furthermore, we discuss modelling approaches that have been developed to predict the interaction of immunotherapy with radiotherapy, and highlight how they could be combined with biomarkers of antitumour immunity to optimize radiotherapy regimens and maximize their synergy with immunotherapy.

Evaluation of failed prosthetic valves in the valve-in-valve era: Potential for utilizing positron emission tomography/computed tomography to recognize infective endocarditis

Bioprosthetic valve dysfunction was treated in the past with redo open heart surgery. The need to identify occult leaflet infection was not an important requirement as all valve tissue was removed during surgery. With the dramatic growth in transcatheter aortic valve replacement (TAVR) valve-in-valve (ViV) therapy, identification of occult infection is of major significance. TAVR should be rarely performed in infected prosthetic valves and the optimal approach should include open heart surgery and removal of infected tissue. With surgical implants, it can be challenging to distinguish infection from degeneration. The use of advanced imaging modalities, including 18F-fluorodeoxyglucose positron emission tomography/computed tomography, in the diagnosis of occult infection is emerging. We report the use of this imaging modality to identify or exclude endocarditis in patients with prosthetic valves who were candidates for ViV therapy.

Microbial biofilm correlates with an increased antibiotic tolerance and poor therapeutic outcome in infective endocarditis

BACKGROUND

Infective endocarditis (IE) is associated with high rates of mortality. Prolonged treatments with high-dose intravenous antibiotics often fail to eradicate the infection, frequently leading to high-risk surgical intervention. By providing a mechanism of antibiotic tolerance, which escapes conventional antibiotic susceptibility profiling, microbial biofilm represents a key diagnostic and therapeutic challenge for clinicians. This study aims at assessing a rapid biofilm identification assay and a targeted antimicrobial susceptibility profile of biofilm-growing bacteria in patients with IE, which were unresponsive to antibiotic therapy.

RESULTS

Staphylococcus aureus was the most common isolate (50%), followed by Enterococcus faecalis (25%) and Streptococcus gallolyticus (25%). All microbial isolates were found to be capable of producing large, structured biofilms in vitro. As expected, antibiotic treatment either administered on the basis of antibiogram or chosen empirically among those considered first-line antibiotics for IE, including ceftriaxone, daptomycin, tigecycline and vancomycin, was not effective at eradicating biofilm-growing bacteria. Conversely, antimicrobial susceptibility profile of biofilm-growing bacteria indicated that teicoplanin, oxacillin and fusidic acid were most effective against S. aureus biofilm, while ampicillin was the most active against S. gallolyticus and E. faecalis biofilm, respectively.

CONCLUSIONS

This study indicates that biofilm-producing bacteria, from surgically treated IE, display a high tolerance to antibiotics, which is undetected by conventional antibiograms. The rapid identification and antimicrobial tolerance profiling of biofilm-growing bacteria in IE can provide key information for both antimicrobial therapy and prevention strategies.

The role of 99mTc-HMPAO-labelled white blood cell scintigraphy in the diagnosis of cardiac device-related infective endocarditis

Aims

The hybrid technique of single-photon emission tomography and computed tomography with technetium99m-hexamethylpropyleneamine oxime–labelled leucocytes (99mTc-HMPAO-SPECT/CT) is an emerging diagnostic technique in patients with cardiac device-related infective endocarditis (CDRIE). This prospective study assessed the 99mTc-HMPAO-SPECT/CT diagnostic profile and its added value to the modified Duke criteria (mDuke) in CDRIE diagnostic work-up.

Methods and results

The study examined 103 consecutive patients with suspected CDRIE, who underwent 99mTc-HMPAO-SPECT/CT. Diagnostic accuracy was calculated based on a final clinical CDRIE diagnosis, including microbiology, echocardiography, and a 6-month follow-up. Subsequently, we compared the diagnostic value of the initial mDuke classification with a classification including 99mTc-HMPAO-SPECT/CT positive results as an additional major CDRIE criterion: mDuke-SPECT/CT.

Overall, CDRIE was diagnosed in 31 (31%) patients, whereas 35 (34%) 99mTc-HMPAO-SPECT/CT were positive. 99mTc-HMPAO-SPECT/CT was characterized by 86% accuracy, 0.69 Cohen’s kappa coefficient, 84% sensitivity, 88% specificity, 93% negative, and 74% positive predictive values. The original mDuke displayed 83% accuracy, 0.52 kappa, whereas mDuke-SPECT/CT had 88% accuracy, and 0.73 kappa. Compared with mDuke, mDuke-SPECT/CT showed significantly higher sensitivity (87% vs. 48%, P &lt; 0.001). According to mDuke, 49.5% of patients had possible CDRIE, and after reclassification, that figure dropped to 37%. Furthermore, having assessed the diagnosis categorization improvement following the incorporation of 99mTc-HMPAO-SPECT/CT, the net reclassification index value was found to be 31.4%.

Conclusion

In patients with CDRIE, 99mTc-HMPAO-SPECT/CT provides high diagnostic accuracy, whereas a negative scan excludes CDRIE with high probability. Inclusion of 99mTc-HMPAO-SPECT/CT into mDuke diagnostic criteria yields significantly higher sensitivity and a reduction in possible CDRIE diagnoses.