Key result
Doppler transvalvular pressure gradients measure ~41% higher than catheter gradients across balloon-expandable and self-expanding valves.
Why the study?
It remains uncertain whether and to what extent transvalvular pressure gradients differ by THV type (BE vs SE) and measurement method (Doppler echocardiography vs cardiac catheterization).
Does Doppler echocardiography overestimate transvalvular pressure gradients compared to cardiac catheterization in balloon-expandable and self-expanding transcatheter heart valves in an in vitro model?
Does Doppler echocardiography overestimate transvalvular pressure gradients compared to cardiac catheterization in balloon-expandable and self-expanding transcatheter heart valves in an in vitro model?
Effect estimate: 40.5% higher
Absolute Event Rate: 9.5% vs 6.3%
p-value: p=<0.001
Doppler echocardiography systematically overestimates transvalvular pressure gradients by approximately 40% compared to catheterization in both balloon-expandable and self-expanding transcatheter heart valves in an in vitro model.
Doppler may overestimate TPGs versus catheterization in THV models; leaves open clinical relevance pending in vivo validation.
OBJECTIVES: The objective of this in vitro study was to compare Doppler versus catheter transvalvular pressure gradients (TPG) in third generations balloon-expandable (BE) versus self-expanding (SE) transcatheter heart valves (THV). BACKGROUND: TPG is a key parameter to assess and follow valve hemodynamic function following transcatheter aortic valve implantation (TAVI). It remains uncertain and debated whether, and to which extent, TPGs differ according to the type of THV, that is, BE versus SE and to the method used for TPG measurement, that is, Doppler echocardiography versus cardiac catheterization. METHODS: The CoreValve EVOLUT PRO 26 mm and the SAPIEN 3 23 mm THVs were tested in a left heart simulator using a 21 mm aortic annulus under following conditions: heart rate: 70 bpm, mean aortic pressure: 100 mmHg, stroke volume: 30, 70 and 100 ml. Mean TPGs were measured by continuous-wave Doppler and by micro-tip pressure catheters positioned in the left ventricle and at 50 mm downstream to the tip of the THV leaflets. RESULTS: Doppler TPGs (9.5 ± 3.9 mmHg) were on average 40.5 ± 13.9% higher (p < 0.001) than catheter TPGs (6.3 ± 3.4 mmHg). Both Doppler and catheter TPGs were lower (p = 0.003) in the SE versus BE THVs (Doppler: 8.7 ± 3.5 vs. 10.7 ± 4.6; catheter: 5.0 ± 1.7 mmHg vs. 7.1 ± 2.2). The Doppler versus catheter difference in TPG increased with the higher flow conditions. The Doppler versus catheter difference in TPG was similar in BE versus SE THVs (3.6 ± 1.1 vs. 3.7 ± 1.4 mmHg or 42 ± 9 vs. 47 ± 9%; p = 0.58) overall and in each flow conditions. CONCLUSION: The Doppler TPGs are, on average, 40% higher than the catheter TPGs for both BE and SE THVs. The SE THV had lower Doppler and catheter TPGs compared to the BE THV, at normal and high flow states. The absolute and percent differences between Doppler versus catheter TPGs were similar in BE versus SE THVs.
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Stanová et al. (2021) studied Transcatheter aortic valve implantation. Doppler echocardiography vs. Cardiac catheterization was evaluated on Mean transvalvular pressure gradients (TPG) (40.5% higher, p=<0.001). Doppler transvalvular pressure gradients (9.5 ± 3.9 mmHg) were on average 40.5% higher than catheter gradients (6.3 ± 3.4 mmHg; p < 0.001) across both balloon-expandable and self-expanding valves.
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