¹⁸F-FDG PET/CT has 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.

To assess the value of the new ESC criteria including PET/CT in prosthetic valve infective endocarditis (PVIE). Secondary objectives: to determine the reproducibility of PET/CT and to assess its ability to predict embolic events.

Between 2014 and 2017, 175patients with suspected PVIE were prospectively included in 3French centers. After exclusion of patients with uninterpretable or not feasible PET/CT, 115patients were finally included, including 91definite IE and 24rejected IE, as defined by a Consensus of Endocarditis Team after 3-month follow-up as Gold Standard. Nuclear data were blindly analyzed by two independent nuclear medicine physicians.

Significant cardiac uptake by PET/CT was observed in 67among 91patients 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 (k=0.63). Embolic events occurred in 31 patients (27%) and were correlated with PET/CT cardiac uptake (P=0.02) among others.

The value of PET CT and ESC criteria is confirmed and may allow earlier diagnosis of PVIE. Reproducibility of nuclear measurements seems unsatisfactory, justifying efforts to standardize PET studies interpretation. Our study describes for the first time a positive correlation between a positive PET/Ct and occurrence of embolic events, warranting additional studies.