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

Abstract

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.

Keywords: CT; Echo; PET; diagnostic and prognostic application; infection; valvular heart disease.

Figure 1

Diagnostic imaging-in-endocarditis-flowchart. Reprinted from The Lancet Infectious Diseases, 17(1), Gomes A, Glaudemans AW, Touw DJ, van Melle JP, Willems TP, Maass AH et al., Diagnostic value of imaging in infective endocarditis: a systematic review, e1–e14, Copyright (2017), with permission from Elsevier

Figure 2

Flow of patients. BSAC, British Society for Antimicrobial Chemotherapy; ICD, implantable cardioverter defibrillator; IE, infective endocarditis; MDCTA, multi-detector computed tomography angiography; PET, ¹⁸F-fluorodeoxyglucose positron emission tomography/low-dose CT; PM, pacemaker; RIE, right-sided endocarditis; TEE, transesophageal; TTE, transthoracic echocardiography

Figure 3

True positive (A)/negative (B) imaging. Figure shows that maximum sensitivity is reached with all techniques combined, but at the cost of decreased specificity. CTA, MDCTA; Echo, (transthoracic and transesophageal) echocardiography; PET, FDG-PET/CT

Figure 4

Illustration of the complementary information provided by different imaging techniques. Data shown for a 73-year-old male with Enterococcus faecalis endocarditis of his biological prosthetic aortic valve and native mitral valve (Table 4 nr. 23, study nr. 10000246): A transthoracic echocardiography, two chamber view, showing the mitral valve with vegetation; B transesophageal echocardiography, mitral commissural 60° view, showing the mitral valve with vegetation; C contrast-enhanced ECG-triggered MDCTA-scan, four chamber view, showing the mitral valve with vegetation; D fused FDG-PET/CT-scan, sagittal and horizontal views, showing FDG-uptake equivocal at the aortic valve (circular) and increased focal at the mitral valve (spot)