Characterization of 18-Fluorodeoxyglucose uptake pattern in infective endocarditis after transcatheter aortic valve implantation

Background 18-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (18-FDG-PET/CT) has been included in the modified Duke criteria to improve the diagnosis of prosthetic valvular endocarditis. However, accuracy of 18-FDG-PET/CT have only been validated in patients with a surgical prosthesis and limited data exist for infective endocarditis related to transcatheter aortic valve implantation (IE-TAVI). Methods The study prospectively included 45 patients who underwent 18-FDG-PET/CT after TAVI. The population was divided in two groups. The control group included 31 consecutive patients who performed a 18-FDG-PET/CT at one after TAVI implantation. The endocarditis group included 14 consecutive patients admitted for IE-TAVI suspicion. The final diagnosis of IE-TAVI was established by the Endocarditis-Team after 3-month follow-up. Results In the control group, 77% (n = 24/31) of patients did not present 18-FDG uptake at one month. 18-FDG uptake was more observed in patients with a conduction abnormality after TAVI (71% [n = 5/7] vs. 17% [n = 4/24], P = 0.01). In the endocarditis group, 18-FDG-PET/CT was positive in all definite-IE (n = 7) and one with rejected-IE (n = 7). Interestingly, the latter patient presented conduction abnormality after TAVI. The SUVmax and the SUV ratio were similar in definite-IE and positive control examinations. In contrast, all uptakes in definite-IE were focal with small spots of uptake (  50% of the aortic valve circumference) in control and rejected-IE. Conclusion Positive 18-FDG-PET/CT examination is uncommon one month after TAVI procedure and the 18-FDG uptake pattern can be easily differentiated from definite-IE. These results indicate that 18-FDG-PET/CT may be used before the 3 months after TAVI procedure to accurately identify IE-TAVI.