18F-Sodium fluoride PET/CT detects transcatheter aortic valve degeneration

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This work was supported by the British Heart Foundation, London, United Kingdom Background Early detection of transcatheter aortic valve implantation (TAVI) degeneration is challenging and only feasible when advanced haemodynamic valve dysfunction is apparent. Purpose We tested whether 18F-sodium fluoride (18F-NaF) positron emission tomography and computed tomography (PET/CT) could detect structural TAVI degeneration and haemodynamic valve dysfunction. Methods After TAVI implantation, patients underwent baseline echocardiography, CT angiography and 18F-NaF PET/CT (Figure). We assessed for morphological changes, stenosis or regurgitation on Doppler echocardiography, CT (hypoattenuated leaflet thickening [HALT] or spotty calcification) and PET (18F-NaF uptake; maximum target-to-background ratio, TBRmax). We categorised structural valve degeneration (SVD) according to the standardised definition for surgical and transcatheter bioprosthetic valves, as proposed in a recent consensus statement. Results We recruited 47 patients (81 ± 6 years old, 79% male) 1 month (n = 9), 2 years (n = 22) or 5 years (n = 16) after TAVI: 25 (53%) had received a balloon expanded bioprosthesis and 22 (47%) a self-expanding valve. There was moderate valve dysfunction on Doppler echocardiography in 3 (6%) patients, HALT on CT in 6 (13%) patients, spotty calcification in one patient and 18F-NaF uptake in 7 patients (15%) (TBRmax range: 1.59-5.88); all enrolled 5 years post-TAVI. All patients with increased 18F-NaF uptake (TBRmax ≥1.59) demonstrated either SVD without haemodynamic valve dysfunction (stage 1, n = 4) or structural valve dysfunction with moderate valve dysfunction and mean transprosthetic pressure gradients >20 mmHg (stage 2, n = 3). In patients without increased 18F-NaF uptake there was no evidence of structural valve degeneration (n = 40). Within the increased 18F-NaF uptake (n = 7) group, patients with stage 2 SVD (n = 3) demonstrated higher uptake compared to patients with stage 1 SVD (TBRmax 4.3 [3.02-5.88] versus 1.8 [1.59-2.28]). Patients with stage 2 SVD (n = 3) had over 3 times higher TBRmax than those without SVD (n = 40) (4.30 [3.02, 5.88] versus 1.31 [1.21, 1.46]; p < 0.001); Figure). Conclusion 18F-NaF PET/CT detects patients with SVD and potentially identifies those at risk of valve failure. Abstract Figure.