2.2 TAVR Durability: What Is It Now and What Do We Need?

These proceedings summarize the educational activity of the 16th Biennial Meeting of the International Andreas Gruentzig Society held January 31-February 3, 2022 in Punta Cana, Dominican Republic

Faculty Disclosures     Vendor Acknowledgments

2022 IAGS Summary Document

Statement of the problem or issue

The first accurate drawings of human cardiac valves were made by Leonardo DaVinci in 1512 and are captured in his notebooks (Figure 1). Leonardo also used wax injections to take molds of the aortic valve of an ox’s heart. Discovering that immediately above the aortic valve leaflets is a widening of the root of the aorta (the sinus of Valsalva), Leonardo made a glass model of that section. He noted he could “see in the glass what the blood does in the heart when it closes the little doors of the heart.” By pumping water with a suspension of grass seeds through the glass model, Leonardo observed turbulent eddies in the sinus, which he concluded were responsible for opening out the cusps when blood flow through the valve ceased after each heartbeat.^1,2

Despite this impressive early understanding, it wasn’t until 1954 that Lilliehei performed the first aortic valve replacement using a mechanical prosthesis, and not until the 1970s that the first bioprosthetic valve replacement was performed. Of course, in 2002 the history of aortic valve replacement changed forever when the first human clinical transcatheter aortic valve replacement (TAVR) procedure was performed (Figure 2).

Generally, in the early phase of its clinical application, TAVR was performed only in high-risk patients, which meant older patients with moderate life expectancy. In the past 2 decades it was learned that lower- and intermediate-risk patients also benefit from TAVR, and this meant younger-aged patients with longer life expectancy (Figure 3). This has led to a large need to identify methods to make TAVR valves last a lifetime for patients, ie, become more durable.³

Gaps in knowledge

Data from several sources reveal that TAVR, as well as surgical valves, deteriorate beyond 5 years, and so, the question remains, what can be done about it?⁴

Possible solutions and future directions

Possibilities to improve valve durability come from 2 primary areas: tissue science and valve design (Figure 4).

Tissue science has seen very little progress until recently. The Resilia valve from Edwards Lifesciences has removed most of the glutaraldehyde from the tissue, a known factor in valve leaflet calcification.⁵ Additionally, Anteris Technologies has developed a new TAVR using an engineered collagen tissue (called ADAPT) that is free of glutaraldehyde as well as DNA, both significant factors in leaflet calcification. Novel polymers such as synthetic PTFE are used in Foldax’s new TAVR valve.

In the other primary area, there is much room for growth and evolution in valve design. Will supra-annular valves be more durable than standard intra-annular valves? Will designs that increase sinus washout enhance durability? How can stent frame geometry be optimized to further enhance valve durability? Are there ways to modify leaflet design to reduce mechanical stress?

As the focus on lifetime management of valve patients grows, we can hope that these and other innovations will help us treat our patients more effectively for much longer ­periods—even a lifetime.

References

1. Keele K, Pedretti C. Leonardo da Vinci: Corpus of the Anatomical Drawings in the Collection of Her Majesty the Queen at Windsor Castle, 2 vols & facsimiles, London 1979-80 – RL 19082 Royal Collection Trust. Accessed June 22, 2022. https://www.rct.uk/collection/919082/the-aortic-valve

2. Philippa Roxby. What Leonardo taught us about the heart. BBC Health: Updated June 28, 2014. Accessed June 22, 2022.https://www.bbc.com/news/health-28054468

3. Bagur R, Pibarot P, Otto CM. Importance of the valve durability-life expectancy ratio in selection of a prosthetic aortic valve. Heart. 2017;103(22):1756-1759. Epub 2017 Sep 13. doi:10.1136/heartjnl-2017-312348

4. Thyregod HGH, Ihlemann N, Jørgensen TH, et al. Five-year clinical and echocardiographic outcomes from the Nordic Aortic Valve Intervention (NOTION) randomized clinical trial in lower surgical risk patients. Circulation. 2019;139:2714-2723. doi:10.1161/CIRCULATIONAHA.118.036606

5. Bartus K, Litwinowicz R, Bilewska A, et al. Intermediate-term outcomes after aortic valve replacement with a novel RESILIA™ tissue bioprosthesis. J Thorac Dis. 2019;11(7):3039-3046. doi:10.21037/jtd.2019.07.33