|Year : 2016 | Volume
| Issue : 1 | Page : 1-4
Multimodality imaging of infective endocarditis in 2015 European Society of Cardiology Guidelines
Enrico Cecchi, Silvia Ferro, Davide Forno, Massimo Imazio
Department of Cardiology, Maria Vittoria Hospital, ASL TO2, Torino, Italy
|Date of Web Publication||10-Mar-2016|
Department of Cardiology, Maria Vittoria Hospital, ASL \TO2, Torino
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Cecchi E, Ferro S, Forno D, Imazio M. Multimodality imaging of infective endocarditis in 2015 European Society of Cardiology Guidelines. J Cardiovasc Echography 2016;26:1-4
|How to cite this URL:|
Cecchi E, Ferro S, Forno D, Imazio M. Multimodality imaging of infective endocarditis in 2015 European Society of Cardiology Guidelines. J Cardiovasc Echography [serial online] 2016 [cited 2020 Nov 28];26:1-4. Available from: https://www.jcecho.org/text.asp?2016/26/1/1/178471
The recent guidelines  on infective endocarditis (IE) of the European Society of Cardiology (ESC) have updated the 2009 ESC guidelines, providing some important changes for imaging experts, especially on the role of multimodality imaging and the role of the “endocarditis team.”
| Endocarditis Team|| |
IE may involve multiple organs and systems with a variable modality of presentation and evolution, on this basis, in clinical practice; the experience of the different specialists participating in the care of a patient with IE (cardiologist, neurologist, rheumatologist, and infectious disease expert) may be limited. Moreover, a high level of experience and technical competence is required for this management. Imaging has a great importance starting from echocardiography but also computed tomography (CT), magnetic resonance, and nuclear imaging (positron emission tomography [PET] and scintigraphy).
Starting from the experience of the French group from Marseille  and the role of the heart team in valvular diseases, current guidelines recommend the management of complicated cases of IE in referral centers with an “endocarditis team” defined according to specific features mentioned in a dedicated table. Referral centers, that should be considered according to functional principles in our view, should allow the immediate access to imaging and cardiac surgery. Several specialists should compose the team including cardiologists, cardiac surgeons, infectious diseases specialists, microbiology experts, anesthetists, subspecialties experts in congenital heart diseases and valvular heart diseases, experts on echocardiography and other imaging techniques, and electrophysiologists with expertise in device explantation.
The “endocarditis team” should have regular meetings to discuss cases, surgical indications, hospital and outpatient management, antibiotic therapies according to standardized protocols, and should provide data and results for registries as well as national and international protocols.
However, the ideal world must deal with the real one, and the debate is currently worldwide.,,
In our opinion, the proposal of a multidisciplinary team of experts that would discuss cases according to strict organizational and therapeutical protocols (according to Marseille experience) is shareable, but difficult to apply for a disease that should be recognized and diagnosed in peripheral centers. On this basis, a network is speculated with spoke and hub centers as for myocardial infarction and this network in countries like Italy is a reality and should be used. Resources of the Cardiothoracic Centers alone would not be sufficient to treat a long-term illness such as IE. However, many Cardiology centers could be referral centers if provided of skill in IE, optimal echocardiographic imaging, and hemodynamic units for primary percutaneous transluminal coronary angioplasty (PTCA), also if cardiac surgery is readily available in the surrounding area.
In fact in our opinion, being a rare disease but with well-distributed cases, it seems appropriate to consider the “endocarditis team” as a functional entity in the Italian reality, with the involvement of expert centers, potentially the hub centers for primary PTCA, that may have specific expertise and technical facilities available on demand when needed. Basically, endocarditis team should include a cardiologist with expertise in imaging, an infectious disease specialist and a cardiac surgeon, other specialist on demand; structures and equipment should be readily available, not necessarily in the same hospital; the ready availability could be inserted in the network of myocardial infarction. The Italian Society of Echocardiography established a commission to search for the best solution and drive this important evolution of IE management.
| Diagnosis Echocardiography Andother Imaging Techniques|| |
At present, IE diagnosis is still difficult and is based on clinical data that give rise to the clinical suspicion of the disease, laboratory data, but especially microbiology results with blood cultures, serology, and molecular biology data, and imaging data. A significant novelty is that additional imaging techniques beyond echocardiography are mentioned including CT, nuclear medicine with PET, and scintigraphy to assess septic vascular events but also for the imaging of cardiac damage and involvement.
Imaging techniques are also important in the management of the disease. Echocardiography has a relevant role for the prognostic stratification, follow-up during medical therapy, before and after cardiac surgery, and for the evaluation of the cardioembolic risk. Transesophageal echocardiography (TOE) is important before and after cardiac surgery and during the operation. Nevertheless, echocardiographic data may be integrated with data from other imaging techniques.
| Echocardiography|| |
The prevalent role of echocardiography is unchanged from previous 2009 ESC guidelines although some aspects have been better clarified. For instance, it has given a recommendation of Class I, LOE B for the use of TOE in suspected IE in the presence of valvular prosthesis or intracardiac device; a recommendation of Class IIa is given to echocardiography (type to be determined according to the disease probability) in sepsis by Staphylococcusaureus. It is not necessary to perform a TOE when a positive transthoracic echocardiography (TTE) is obtained in case of IE on a native valve in the right chambers. It is unchanged the diagnostic algorithm for the use of echocardiography. Among the echocardiographic data that are major diagnostic criteria, a pseudoaneurysm is defined as a pulsatile perivalvular echo-free space with color Doppler flow detected [Figure 1]. Anatomically, it is also defined as a perivalvular cavity communicating with the cardiovascular lumen. Furthermore, valvular perforation or aneurysm and intracardiac fistula have been considered major echocardiographic criteria.
|Figure 1: Typical pseudoaneurysm: Pulsatile perivalvular echo-free space with color Doppler fl ow detected|
Click here to view
Sensitivity and sensibility of echocardiography are <100% also with the use of TOE. Echocardiographic data should be interpreted in the clinical context also taking into account other laboratory and imaging data from other available techniques.
Compared with 2009 ESC guidelines, it is clearer when to repeat an echocardiogram in case of persistent clinical suspicion of IE. In cases with an initially negative examination, repeat TTE/TOE must be performed 5-7 days; later, if the clinical level of suspicion is still high, or even earlier in the case of S.aureus infection.
The potentiality of real-time three-dimensional (3D) echocardiography, especially TOE is underlined. Real-time 3D TOE allows a better analysis of vegetation morphology and size, a better prediction of its embolic risk, a better evaluation of perivalvular extension of the infection, prosthetic valve dehiscence, and valve perforation. Although in clinical practice 3D TOE is increasingly performed along with conventional TOE in many centers, at present, 3D TOE should still be regarded as a supplement to standard echocardiography in most cases. Traditional TOE is a main-stay as diagnostic tool.
| Multislice Computed Tomography|| |
La multislice computed tomography (MSCT) should be considered for the evaluation of coronary artery disease in patients with IE to avoid the potential risks of vegetation embolization and/or hemodynamic decompensation during coronary angiography.
MSCT can be used to detect abscesses/pseudoaneurysms with a diagnostic accuracy similar to TOE, and is possibly superior in the provision of tridimensional informations regarding the extent and consequences of any perivalvular extension, including the anatomy of pseudoaneurysms, abscesses, and fistulae. In aortic IE, this technique may provide additional data on the size, anatomy and calcification of the aorta, which may be very useful for surgical planning. In pulmonary/right-sided endocarditis, CT is useful to study concomitant pulmonary disease, including abscesses and infarcts.
In the evaluation of vegetations, abscesses, pseudoaneurysms, and prosthetic dysfunction, CT is considered comparable to echocardiography. However, this statement should be judged with caution since there is only one study for the evaluation of vegetations, and comparisons are lacking with TOE that should be considered the method of choice for the study and characterization of vegetations.
Magnetic resonance imaging (MRI) has a higher sensitivity compared with CT for the detection of cerebral lesions also in the context of IE. However, in the critically ill patient, CT may be more feasible and practical and is an acceptable alternative when MRI is not available.
MSCT angiography allows complete visualization of the intracranial vascular tree and carries a lower contrast burden and risk of permanent neurological damage than conventional digital subtraction angiography, with a sensitivity of 90% and specificity of 86%. After a subarachnoid and/or intraparenchymal hemorrhage, other vascular imaging (i.e. angiography) is required to diagnose or exclude a mycotic aneurysm if not detected on CT.
Contrast-enhanced MSCT allows making the diagnosis of splenic and other abscesses with a high diagnostic accuracy; however, the differentiation with infarction can be challenging. MSCT angiography provides a rapid and comprehensive exploration of the systemic arterial bed, allowing the identification of peripheral vascular complications.
| Magnetic Resonance Imaging|| |
MRI has a higher sensitivity than CT for the detection of cerebral consequences of the acute phase of IE. Studies have shown frequent lesions, in 60-80% of patients. Most abnormalities are small ischemic lesions (in 50-80% of patients), in <10% of patients parenchymal or subarachnoidal hemorrhages, abscesses, or mycotic aneurysms are found.
If a positive MRI study is considered as one minor Duke criterion in the absence of symptoms, in one study, 25% of patients presenting initially with nondefinite IE had a definite diagnosis after MRI study that thus contributed to an early diagnosis.
Cerebral microbleeds are found in 50-60% of patients with IE. Microbleeds represent small areas of hemosiderin deposits and are considered as an indicator of small vessel disease, and not embolic events. On this basis, although microbleeds are frequent in IE, microbleeds should not be considered as a minor criterion in the Duke classification.
In IE patients with neurological symptoms, MRI is frequently abnormal and has a higher sensitivity than CT in the diagnosis of the culprit lesion for stroke, transient ischemic attack, and encephalopathy.
In these patients with already one minor Duke criterion, MRI does not improve the diagnostic accuracy but may impact the therapeutic strategy.
Abdominal MRI detects lesions in one of three patients, most often affecting the spleen; nevertheless, abdominal MRI findings have no incremental diagnostic value when taking into account the findings of cerebral MRI.
| Nuclear Imaging|| |
With the introduction of hybrid equipment, single-photon emission CT (SPECT) and PET may be used with CT (SPECT/CT and PET/CT).
SPECT imaging relies on the use of autologous radiolabeled leukocytes (marked with In 111 or Tc 99m) that accumulate in late images while PET is performed after the administration of 18F-fluorodeoxyglucose, which is actively incorporated invivo by inflammatory cells (activated leukocytes, monocyte-macrophages, and CD4+ T-lymphocytes).
Several reports have shown promising results, especially for the detection of peripheral embolic events that allows transforming cases of possible IE as cases with definite IE. Limitations to the use of PET/CT are represented by localization of septic emboli in the brain, due to the high physiological uptake of this tracer in the brain cortex, and to the low sensitivity for lesions <5 mm that are the majority. Other false positive results can be found in patients who have recently undergone cardiac surgery, as well as other situations (active thrombi, soft atherosclerotic plaques, vasculitis, primary or secondary cardiac tumors, and foreign body reactions).
SPECT/CT is more specific than PET/CT, but the need for blood handling for radiopharmaceutical preparation, the duration of the procedure, and a lower spatial resolution and thus less sensitivity compared with PET/CT.
An additional promising role of PET/CT could be to monitor the response to antimicrobial treatment.
| Diagnostic Criteria|| |
Current guidelines do not overturn Duke University diagnostic criteria, but since they have a sensitivity of about 80%, that is even lower in case of prosthesis and intracardiac devices, where echocardiography is not able to well characterize about 30% of cases, the new guidelines propose new diagnostic criteria that consider the potentiality of integrated multimodality imaging. Integrated multimodality imaging is especially able to detect silent vascular phenomena as well as an endocardial lesion. The intention is to better characterize the anatomical damage with a functional evaluation. On this basis, new definitions include:
- Major criterion: The identification of paravalvular lesions by cardiac CT.
- Major criterion: In the setting of the suspicion of IE on a prosthetic valve (if the prosthesis was implanted for >3 months) the presence of abnormal activity around the site of implantation detected by PET or SPECT.
- Minor criterion: The identification of silent embolic events or infectious aneurysms by imaging.
The diagnostic algorithm is still based on blood cultures and echocardiography as major diagnostic criteria, but if IE remains “possible” or “rejected” with a high degree of clinical suspicion, blood cultures, and echocardiography should be repeated, but also integrated with the search for cardiac involvement by CT or PET or SPECT/CT and the search for peripheral embolic events (cerebral MRI, total body CT or PET/CT).
In our opinion, it is essential the search of peripheral embolic events by emerging imaging techniques as indicated in the guidelines. It is also certain the utility of CT to assess and confirm paravalvular involvement in doubtful cases with TOE and to better characterize the extension and involvement of contiguous structures. In our opinion, there are still insufficient data to support the use of PET as major criterion to assess intramyocardial damage, because of a high proportion of false positive, while SPECT may have low sensitivity for this assessment.
Regarding the new proposed diagnostic criteria, it is necessary to collect further studies to validate and support their possible incremental role, also considering the increased costs of the proposed imaging techniques.
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Conflicts of interest
There are no conflicts of interest.
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