Valve Durability
The durability requirement.
Transcatheter Aortic Valve Implantation (TAVI) is the biggest revolution in heart valve treatment in our lifetime because it allows for the replacement of a diseased heart valve without open-heart surgery. This new therapy has recently become the standard of care for octogenarian Aortic Stenosis (AS) patients. However, younger patients still require open-heart surgery because the durability of TAVs has not been sufficiently established compared to that of surgical aortic valves, which last 12 to 18+ years.
Initial long-term trials (> 6 years) of approved TAVs show significant signs of deterioration in 50% of surviving patients by about year 7*. Most of these trials have been on octogenarians; valve deterioration is expected to arise even earlier in younger patients because they have higher rates of calcification. For patients, this may mean a return of their AS symptoms, and even a reintervention.
To carry this revolutionary therapy forward, a more durable valve is required. The Optimum TAV, with its superior durability and hemodynamic performance, is designed to treat even younger patients.
* Source: Dvir, D. First look at long-term durability of transcatheter heart valves: Assessment of valve function up to 10 years after implantation. EuroPCR 2016.
How the Optimum TAV demonstrates superior durability
Animal Studies
The Optimum TAV demonstrates superiority to surgical valves in sheep studies, the Gold Standard preclinical durability test.
Low calcification in 5-month sheep studies is known to be highly correlated with long-term clinical durability of tissue surgical valves (TSVs). TSVs have been used for over 50 years and are known to last 12 to 18+ years in patients. Sheep studies are considered the best preclinical indicator of durability because valve degeneration primarily occurs as a result of calcification, and the young sheep used in these studies have very high rates of calcification.
In sheep studies, the Optimum TAVs exhibited less calcification than TSVs. Pressure gradients and other parameters of valve function were also extraordinary, and superior to any data published on a transcatheter aortic valve.
Accelerated Wear Test
The Optimum TAV showed NO signs of wear after completing 890 million cycles, whereas the surgical valve control developed holes and tears at only 500 million cycles.
Testing replicated the conditions of a real procedure, including: the Optimum TAVs were first crimped and deployed via catheter. ISO/FDA standards require only 200 million cycles. The valves completed 890 million cycles, simulating > 24 years of life, at ΔP ≥ 100mm Hg. They showed no signs of wear, including no holes, no tears, and no tissue disruption. The valves were then halted to conduct failure testing, and extraordinary measures were required to fail them.
A conversation on durability
Dr. Jeffrey Popma, Dr. Danny Dvir, and Dr. Mano Thubrikar discuss the durability of surgical aortic valves, transcatheter aortic valves, and the Optimum TAV at the Baim Institute for Clinical Research in Boston.