Long-Term Calcification of Transcatheter and Surgical Aortic Valves under Standardized Ex Vivo Condition

Background: Structural valve deterioration mainly caused by calcification is known as the Achilles heel of bioprosthetic heart valves (BHV). While clinical long-term experience of surgical aortic valve bioprostheses (SAV) exists, transcatheter heart valve (THV) requires further investigations in biological degeneration. Therefore, the aim of this in vitro study was to analyze calcification pattern of TVH and SAV under standardized conditions.

Method: THVs (Evolut PRO 26 mm and Sapien XT 23 mm) and SAVs (Hancock II, Mosaic Ultra, Perimount and Perimount Magna Ease; all 23 mm) models were calcified with a physiological buffer (pH = 7.4; KCl = 55 mM, CaCl₂ = 1.5 mM, KH₂PO₄ = 1.25 mM, Na₂HPO₄ = 0.32 mM, NaH₂PO₄ = 0.11 mM) circulating at 37°C over 157.684 million cycles in a Hi-Cycler to simulate 5 patient-years. The calcified group and one untreated prosthesis of each BHV model (control group) were analyzed (n = 12) by macroscopic evaluation, tissue thickness measurement, calcium titration, scanning electron microscopy, and histological examination. Hydrodynamic performance (mean pressure gradient (MPG) and effective orifice area (EOA)) were compared in a pulse duplicator before and after calcification.

Results: The calcified group presented hydroxyapatite crystals, tissue decentralization, loss of nucleus and elastic fibers, while the control group showed no sign of calcification. Calcium value was significant higher in all BHV after calcification (p < 0.001). The highest calcium value was found in Perimount and the lowest in Evolut PRO after calcification. MPG and EOA of all BHV changed significantly (p < 0.05) with exception of Evolut PRO (p > 0.05) after durability testing.

Conclusion: These findings suggest patient specific individualized selection of BHVs with regard to patients’ risk factors for calcification to achieve good long-term results. Further clinical evaluation is essential to confirm calcification behavior of in vivo implanted BHVs.

Prosthesis	NoncalcifiedCa (µg/cm2)	CalcifiedCa (µg/cm2)	NoncalcifiedMPG (mm Hg)	CalcifiedMPG (mm Hg)	Noncalcified EOA (cm2)	CalcifiedEOA (cm2)
Hancock II	3.1 ± 0.3	2,875 ± 89	6.4 ± 1.1	8.6 ± 1.9	1.8 ± 0.1	1.5 ± 0.1
Mosaic Ultra	4.1 ± 0.3	2,105 ± 94	10.6 ± 3.3	15.7 ± 3	1.7 ± 0.1	1.4 ± 0.1
Perimount	3.2 ± 0.2	3,528 ± 1,158	4.9 ± 0.4	16.4 ± 2.3	2.2 ± 0.4	1.0 ± 0.1
Magna Ease	4.1 ± 0.2	2,273 ± 143	3.6 ± 0.4	6.8 ± 1.4	2.3 ± 0.3	1.7 ± 0.1
Evolut PRO	2.9 ± 0.2	812 ± 67	4.1 ± 0.4	4.7 ± 0.8	2.1 ± 0.2	2.1 ± 0.2
Sapien XT	3.4 ± 0.2	769 ± 102	7.2 ± 1.3	8.2 ± 1.5	1.8 ± 0.1	1.5 ± 0.1

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Artikel online veröffentlicht:
28. Januar 2023