Steven Yakubov, MD, director of the MidWest Cardiology Research Foundation at OhioHealth Riverside Methodist Hospital, looked at overall valve performance for this study. This included structural valve deterioration, non-structural valve deterioration, thrombosis and endocarditis. Overall, surgery had more valve dysfunction than TAVR.

"We also showed in this trial, as we have in every other Evolut trial, that hemodynamics were positive for TAVR at every time point tested and there's less patient prosthetic mismatch. All these things affect mortality. So now we roll forward to our low-risk four year data. Our endpoint of all cause mortality, disabling stroke was three and a half times lower in TAVR than it was in surgery," Reardon explained. 

Key takeaways from the Evolut Low Risk trial

Reardon pointed out some of the key study findings that highlighted TAVR's superiority over surgery:

   • Overall valve performance: TAVR showed better overall valve performance compared to SAVR, considering structural valve deterioration, non-structural valve deterioration, thrombosis and endocarditis. Better valve performance was associated with improved mortality and hospitalization outcomes, Reardon said.

   • Mortality and stroke rates: The four-year data showed that all-cause mortality and disabling stroke were significantly lower in the TAVR group, with the advantage of TAVR increasing over time. The trend favored TAVR for all-cause mortality, and stroke rates remained low, likely due to low thrombosis rates with TAVR.

   • Pacemaker rates: The pacemaker rate was discussed as a point of concern in previous TAVR trials. At one year, the pacemaker rate was around 17%, but the adoption of the cusp overlap view when implanting TAVR valves helped that rate fall to less than 10%.

   • Patient characteristics: The average age of the patients in the trial was around 74 years old, with only about 23% of them being less than 70. These patients were considered low risk but slightly older, and the decision to perform TAVR or SAVR was based on guidelines that consider age, anatomy and patient preferences.

Future TAVR trends and valve durability

There has been some debate about intervening with TAVR in younger patients. While guidelines recommend SAVR for those under 65, the field is gradually moving toward using TAVR in younger patients, which may pose challenges in terms of valve durability and function over a longer timeframe. 

The new data from TCT will likely lead to more younger patients seeking TAVR as an alternative to open heart surgery. Early on durability of the valve was not a major factor because its was being implanted in very sick elderly patients who were too high risk for surgery and most were not expected to live more that five to 10 years. However, that has changed rapidly in the past decade.

"As we move the younger patients, death becomes less of a competing risk and the durability of the valve and the function of the valve become more and more important," Reardon explained.  

The original thought was that TAVR valves would wear out faster than surgical valves because they are crimped to make them small enough to be delivered via catheters, but that shorter service life has not yet been seen. Trial data, including statistics from the current 4-year low-risk results, actually show TAVR valves may have better durability than SAVR valves. 

Despite these findings, however, Reardon still thinks SAVR makes more sense for younger patients.

"In theory, you go as low as you want to go, but if you're less than 65, unless you have other things going on, we'll recommend surgery for you. Particularly if your anatomy is not just absolutely perfect for TAVR," Reardon said. He also considers extenuating circumstances in the decision making for younger patients. He had a 63-year-old man whose wife was dying and he was her primary caregiver, so for him it was more important to get the patient back home as soon as possible.

"We did a TAVR, and he understands at 63, he's going to be back," Reardon said. "But it meant something for him to be back as quickly as possible because his wife was probably only has six or eight months. So there are these extenuating circumstances that we all see in our clinical practice."

The average life span of a surgical valve is about 15 to 20 years, so most younger patients will need at least a second intervention later in life. Since TAVR is minimally invasive, it was originally envisioned for use in older, more frail patients who will not recover as well with surgery. TAVR experts have been suggesting the past few years that surgery is a better choice when patients are younger, and saving TAVR for later in life when they are more frail. But, Reardon also said durability of TAVR and some of the newer surgical valves are not known. Until more long-term data is released, it is difficult to say if TAVR should be used for a first procedure in younger patients.

TAVR is limited in that a second TAVR valve can be placed inside an existing TAVR valve, but a third would be too restrictive and limit flow, so surgical replacement would be required. However, Reardon said new, slimmer TAVR valves for valve-in-valve replacements are also being developed, so it might be possible that new technologies may better enable multiple TAVRs in a few years.

Reardon referenced the NOTION trial, from 2009, which offers ten-year data on the first-generation CoreValve TAVR device. He said the data revealed no significant difference in mortality between TAVR and SAVR, suggesting that TAVR valves can provide durable outcomes, even in older patients.