333018F-Fluorodeoxyglucose Positron Emission Tomography Computed Tomography (PET/CT) for the diagnosis of prosthetic valve infective endocarditis (PVIE): a prospective multicenter study

Background and objectives

18F-FDG PET/CT has recently been added as a major criterion in the ESC 2015 infective endocarditis (IE) guidelines, but the value of this new diagnostic algorithm has never been prospectively assessed.

Purposes

1. Primary objective: to assess the value of the new ESC criteria including 18F-FDG PET/CT in prosthetic valve infective endocarditis (PVIE).

2. Secondary objectives: to determine the reproducibility of 18F-FDG PET/CT; to assess its ability to predict embolic events.

Methods

Between 2014 and 2017, 175 patients with suspected PVIE were prospectively included in 3 French centers. After exclusion of patients with uninterpretable or not feasible PET/CT,115 patients were finally included in the analysis, including 91 definite IE and 24 rejected IE, as defined by an expert Consensus of Endocarditis Team after 3-month follow-up as Gold Standard

Nuclear data were blindly analyzed by two independent nuclear medicine physicians.

Patients follow-up was scheduled at one and three months after hospitalization

Results

Significant cardiac uptake by PET/CT (major criterion) was observed in 67 among 91 patients with definite PVIE and 6 patients with rejected IE (sensitivity 73.6%, specificity 75%, positive predictive value 91%, negative predictive value 42%). Considering cardiac uptake as a major criterion, the ESC 2015 classification increased the sensitivity of Duke criteria from 57 to 84% (p<0.001) but decreased its specificity from 84 to 70% (p<0.001).

Intraobserver reproducibility of cardiac uptake evaluation was good (kappa = 0.84) but inter observer reproductibility was less satisfactory (kappa = 0.63).

Embolic events occurred in 31 patients (27%) and were correlated with vegetation size by ECHO (p<0.001), Staphylococcus infection (p=0.003), and PET/CT cardiac uptake (p=0.02).

Conclusion

1. the value of PET CT and ESC criteria is confirmed and may allow earlier diagnosis of PVIE

2. PET CT is associated with an increased risk of false positive results probably related to the technical improvements

3. Reproducibility of nuclear measurements seems unsatisfactory, justifying efforts to standardize PET studies interpretation

4. Our study describes for the first time a positive correlation between a positive PET/Ct and occurrence of embolic events, warranting additional studies.