People with a small aortic annulus, part of the heart’s anatomy where the left ventricle meets the aorta, who underwent transcatheter aortic valve replacement (TAVR) with a supraannular self-expanding valve saw similar clinical outcomes and superior valve performance at one year compared with those who underwent balloon-expandable valve TAVR, according to research presented at the American College of Cardiology’s annual scientific session.
The SMART trial is the first randomized crossover comparison of the two most widely used TAVR devices—the hyperannular self-expandable Evolut PRO/PRO+/FX and the balloon-expandable SAPIEN 3/3 Ultra. It is also the first to specifically focus on informing device selection for patients with small aortic rings, a patient group that is predominantly female and has been underrepresented in previous TAVR clinical trials.
We believe it is important to study this population, which represents up to 40% of all patients receiving TAVR, and it is important to study women, who make up the majority of the small ring population. There was a huge difference—32.2 percentage points—in one-year bioprosthetic valve dysfunction favoring the Evolut platform. The magnitude of the hemodynamic difference was greater than we expected.”
Howard C. Herrmann, MD, John W. Bryfogle Professor of Cardiovascular Medicine at the Perelman School of Medicine at the University of Pennsylvania, chief of interventional cardiology at the Hospital of the University of Pennsylvania and lead author of the study
TAVR is a procedure to replace an aortic valve that has narrowed too much and doesn’t open fully, forcing the heart to work harder to pump blood. A new valve is inserted through a catheter passed through a blood vessel, most often in the leg, and placed in place without removing the existing valve.
The trial involved 716 patients undergoing TAVR at 83 international sites in North America, Europe and the Middle East. Patients had a valve annulus of 430 mm2 or less and anatomy suitable for either the Evolut PRO/PRO+/FX or the SAPIEN 3/3 Ultra. Eighty-seven percent of study participants were women, and participants were considered to be at low to intermediate risk of major cardiac events on a baseline risk assessment.
Half of the participants were randomly assigned to receive the self-expanding Evolut valve, which is made using pig tissue and materials that allow the valve to expand to full size when it reaches body temperature. The other half of the participants received the SAPIEN balloon-expandable valve, which is made from bovine tissue and is inserted into the heart valve using a balloon to expand to full size.
At one year, the trial met both primary endpoints. The researchers found no significant difference between the groups in the composite of death, disabling stroke or readmission to hospital for heart failure – which occurred in 9.4% of patients who received the Evolut valve and 10.6% of those who received the SAPIEN valve. In addition, the Evolut valve was found to be superior in terms of valve function, defined as a composite of structural and nonstructural valve wear, perivalve blood clotting, valve contamination, and aortic valve reoperation. This endpoint of composite valve function occurred in 9.4% of patients who received the Evolut valve and 41.6% of those who received the SAPIEN valve.
All prespecified secondary endpoints were statistically significant in favor of the self-expanding valve, including blood pressure across the valve and valve opening size. Herrmann said the hyper-annular design of the self-expanding valve likely accounted for the superior hemodynamics seen in the study, as it allowed valves with a larger opening than the balloon-expandable platform to be implanted.
The researchers said the results are reassuring in terms of the clinical outcomes of both types of valves, and noted that further follow-up could help shed light on how the two devices perform in this patient population over the long term, when the difference in function valve may affect valve life. The researchers will continue to monitor the results over the next five years.
“The fact that we had similar clinical results at one year is an important finding because many people believe that one valve is better than the other, and here in a randomized trial, at least at one year in a subgroup of patients, the clinical differences were not they were different,” Herrmann said. “The trial gives us a lot of information. Clinically, at one year, both valves are reasonable and the results are quite similar, although mild valve leaks and some measures of quality of life were better with the Evolut. Furthermore, this is the first time to identify differences between devices that may later affect patient outcomes.”
Similar results were seen in all subgroups, although the researchers plan to analyze additional subgroups to determine whether valve performance or clinical outcomes may differ among individuals of different age groups or among individuals with different comorbidities or annulus size. They also plan to assess measures of valve strength over time, which Herrmann said is becoming more important as younger patients increasingly undergo TAVR.
The study was funded by Medtronic, Inc., manufacturer of the Evolut PRO/PRO+/FX.
This study was simultaneously published online at New England Journal of Medicine at the time of presentation.
Herrmann will be available to the media at a press conference on Sunday, April 7, 2024 at 11:15 a.m. ET / 4:15 PM UTC in Room B203.
Herrmann will present the study, “Self-expandable balloon-expandable aortic valve replacement in patients with small aortic annulus: Primary results from the SMART randomized trial,” on Sunday, April 7, 2024 at 9:45 a.m. ET / 13:45 UTC.
