Results of the SMART trial, comparing the use of two widely deployed transcatheter aortic valve implantation (TAVI) systems in patients with small aortic annuli, has found that the use of a supra-annular self-expanding valve resulted in similar clinical outcomes and superior valve performance at one year compared with a balloon-expandable valve.
The SMART randomised trial compared the supra-annular self-expanding Evolut (Medtronic) family of TAVI valves, which includes the Evolut PRO, PRO+ and FX iterations of the system, and the balloon-expandable Sapien 3 and Sapien 3 Ultra (Edwards Lifesciences). The trial is the first to focus specifically on informing device selection for patients with small aortic annuli, a patient group that is primarily women and has been underrepresented in previous clinical trials for TAVI.
“We think it’s important to study this population, which represents up to 40% of all patients getting TAVI, and it’s important to study women, who make up the majority of the small annulus population,” said trial investigator Howard Herrmann (Perelman School of Medicine at the University of Pennsylvania, Philadelphia, USA) , the study’s lead author, who presented the results at the American College of Cardiology (ACC) 2024 scientific session (6–8 April, Atlanta, USA). “There was a huge difference— 32.2 percentage points—in one-year bioprosthetic valve dysfunction favouring the Evolut platform. The magnitude of the haemodynamics difference was larger than we expected.”
The trial enrolled 716 patients who underwent TAVI at 83 international sites in North America, Europe and the Middle East. Patients had a valve annulus of 430mm2 or less and anatomy suitable for either the Evolut or the Sapien 3 devices. Eighty-seven percent of study participants were women and participants were considered to face a low to intermediate risk of serious cardiac events in a baseline risk assessment.
Half of the participants were randomly assigned to receive the self-expanding Evolut valve, which is constructed using porcine tissue and materials that allow the valve to expand to full size when it reaches body temperature. The other half of participants received the balloon-expandable Sapien valve, which is made from bovine tissue and inserted inside the heart valve by using a balloon to expand to full size.
At one year, the trial met both primary endpoints. Researchers found no significant difference between groups in terms of a composite of death, disabling stroke or rehospitalisation for heart failure—which occurred in 9.4% of patients who received the Evolut valve and 10.6% of those receiving the SAPIEN valve.
In addition, the researchers report that the Evolut valve was found to be superior in terms of valve function, defined in terms of a composite of structural and non-structural valve deterioration, blood clotting around the valve, infection of the valve and aortic valve reintervention. This composite valve function endpoint occurred in 9.4% of patients who received the Evolut valve and 41.6% of those receiving the Sapien valve.
All pre-specified secondary endpoints were statistically significant in favour of the self-expanding valve, including the blood pressure across the valve and the size of the valve opening. Herrmann said that the supra-annular design of the self-expanding valve likely accounts for the superior haemodynamics observed in the study, since it allowed for implantation of valves with a larger opening than the balloon-expandable platform.
Researchers said the results are reassuring in terms of the clinical outcomes of both valve types and noted that further follow-up could help to shed light on how the two devices perform in this patient population in the long-term when the difference in valve function may affect how long the valve lasts. Researchers will continue to track outcomes over the next five years.
“The fact that we had similar clinical outcomes at one year is an important finding because a lot of people think one valve is better than the other, and here in a randomised trial, at least at one year in a subset of patients, the clinical differences weren’t different,” Herrmann said. “The trial gives us a tonne of information. Clinically, at one year, either valve is reasonable, and the results are pretty similar, although mild valve leaks and some measures of quality of life were better with Evolut. Furthermore, this is the first time we get to identify differences between the devices that might impact later patient outcomes.”
Similar results were seen across all sub-groups, although the researchers plan to analyse additional subgroups to determine whether valve performance or clinical outcomes may vary among people in different age groups or among people with different comorbidities or annulus size. They also plan to assess measures of valve durability over time, which Herrmann said is becoming more important as younger patients are increasingly undergoing TAVI.
Relfecting on the results, Herrmann told Cardiovascular News: “This should prompt TAVI operators to strongly consider the Evolut prosthesis for all patients with a small aortic annulus, the great majority of whom are women in order to obtain the best valve performance without compromising clinical outcomes in the short run (one year) and potentially also improve long term outcomes and valve durability. This latter point is why we are planning to follow the patients for five years.”
“SMART was launched to better understand how the two most commonly used TAVI systems perform in patients with small aortic annuli, and particularly in women who tend to have smaller heart valves,” said Nina Goodheart, senior vice president and president, Structural Heart & Aortic, which is part of the Cardiovascular Portfolio at Medtronic said in a press release issued by the company. “We continue to develop evidence to better understand the benefits of our Evolut TAVI technology in all patients, including patient populations that are underrepresented, under-diagnosed and under-treated. The results from the SMART trial demonstrate these benefits in a large patient population and reinforce our commitment to driving health equity and engineering the best technology to solve unmet patient needs.”
The results were simultaneously published online in the New England Journal of Medicine at the time of presentation.
