In small aortic annuli, self-expanding TAVR valve may be preferred for hemodynamics
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Key takeaways:
- In patients with small aortic annuli requiring TAVR, self-expanding valves had better hemodynamic results than balloon-expandable valves at 1 year.
- 87% of participants enrolled were women.
ATLANTA — In patients with severe aortic stenosis and a small aortic annulus undergoing transcatheter aortic valve replacement, hemodynamic parameters were best with a self-expanding valve, according to data from the SMART trial.
Results presented at the American College of Cardiology Scientific Session and simultaneously published in The New England Journal of Medicine showed no differences at 1 year in clinical outcomes between patients assigned a self-expanding TAVR valve (Evolut Pro, Evolut Pro+ or Evolut FX, Medtronic) and those assigned a balloon-expandable valve (Sapien 3/3 Ultra, Edwards Lifesciences).
In addition, “this is the first trial in the TAVR space to enroll primarily women,” Howard C. Herrmann, MD, section chief of interventional cardiology at the Hospital of the University of Pennsylvania and system director of interventional cardiology, the John Winthrop Bryfogle Professor of Cardiovascular Diseases and professor of medicine in surgery at Penn Medicine, said during the late-breaking clinical trial presentation.
Understanding the differences
Over years of experience with TAVR valves, “it became obvious to me as well as many other investigators that the hemodynamics of the Evolut valve were better than the Sapien valve,” Herrmann told Healio. “It seemed like that was an advantage that was not being exploited by Medtronic, but more importantly, exploited for patient benefit. So I brought to Medtronic the idea of a study comparing the two TAVR valves. Aside from a few small ones in Europe, no studies had been done at that point comparing two TAVR prostheses to each other. Eventually, Medtronic decided they liked the idea. We know that hemodynamic valve performance is linked to long-term outcomes in many studies, and that these hemodynamic differences are more marked in patients who have a small annulus. It happens that most of those patients are women, so we designed a trial with a high proportion of women, almost 90%. Understanding not only the differences between the prostheses, but between them in women, was important.”
Herrmann and colleagues assigned 716 patients with symptomatic severe aortic stenosis and an aortic valve annulus area of 430 mm2 or less (mean age, 80 years; 87% women; mean Society of Thoracic Surgeons Predicted Risk of Mortality, 3.3%) to undergo TAVR with a self-expanding valve or a balloon-expandable valve.
The coprimary endpoints were death, disabling stroke or rehospitalization for HF at 12 months and bioprosthetic valve dysfunction at 12 months. Bioprosthetic valve dysfunction was a composite endpoint including hemodynamic structural valve dysfunction, defined as an aortic valve mean gradient of 20 mm Hg or more; nonstructural valve dysfunction, defined as severe prosthesis-patient mismatch or moderate or worse total aortic regurgitation, clinical valve thrombosis, endocarditis or aortic valve reintervention.
The self-expanding valve was noninferior to the balloon-expandable valve for death, disabling stroke or rehospitalization for HF at 12 months (self-expanding group, 9.4%; balloon-expandable group, 10.6%; difference, –1.2 percentage points; 90% CI, –4.9 to 2.5; P for noninferiority < .001), Herrmann said during the presentation.
Bioprosthetic valve dysfunction at 12 months occurred in 9.4% of the self-expanding group but 41.6% of the balloon-expandable group (difference, –32.2 percentage points; 95% CI, –38.7 to –25.6; P for superiority < .001), he said.
The hemodynamic and valve dysfunction metrics were as follows (P < .001 for all):
- hemodynamic structural valve dysfunction: self-expanding, 3.5%; balloon-expandable, 32.8%;
- percentage of women with bioprosthetic valve dysfunction: self-expanding, 10.2%; balloon-expandable, 43.3%;
- moderate or severe patient-prosthesis mismatch at 30 days: self-expanding, 11.2%; balloon-expandable, 35.3%;
- mean effective orifice area: self-expanding, 1.99 cm2; balloon-expandable, 1.5 cm2; and
- aortic valve mean gradient: self-expanding, 7.7 mm Hg; balloon-expandable, 15.7 mm Hg.
‘The suspicion ... is now proven’
“The suspicion that the Evolut valve had better hemodynamics is now proven,” Herrmann told Healio. “I think what we proved in this population is the magnitude of that difference, which was more than I expected and more than what we calculated at the beginning of the trial would be different. We did not see clinical differences at 1 year, but, frankly, we did not really expect to. This was a relatively low-risk population. Most of the studies to date have shown that hemodynamics affects outcomes by 5 years. This magnitude of difference I expect will lead to differences in clinical outcomes before 5 years, because it is accentuated in a small aortic annulus population.”
Self-expanding valves have traditionally produced a higher rate of new permanent pacemaker implantations compared with balloon-expandable valves, but in SMART, the difference was not significant (self-expanding, 12.1%; balloon-expandable, 7.8%; HR = 1.61; 95% CI, 0.98-2.65), Herrmann told Healio.
“The newer devices and the use of the cusp overlap technique has led to a reduction in pacemaker rates with Evolut,” he said. “Other safety outcomes were essentially the same between the two devices.”
He also said the self-expanding valve was associated with less aortic insufficiency and better Kansas City Cardiomyopathy Questionnaire ordinal scores compared with the balloon-expandable valve.
Herrmann told Healio that “this difference in valve hemodynamics should be a strong consideration when choosing a valve for a woman with a small aortic annulus. Based on the fact that there’s a large difference in valve performance and no difference in clinical outcomes at 1 year, [Evolut] should be the ideal, if not preferred, valve for these patients.”
In an email to Healio, Amar Patel, MD, co-director of the Structural Heart and Valve Program at Wellstar Center for Cardiovascular Care and a site principal investigator for the SMART trial, said “It’s important to find the best valve option for each patient, aiming for longevity. With advancements like predictive modeling, we're moving toward more accurate predictions of how long valves will last. This is crucial for managing conditions like aortic valve stenosis, where patients may need multiple valves in their lifetime. The goal remains to provide patients with the longest-lasting options, whether it's through tissue-based valves or exploring synthetic alternatives that could potentially offer even greater durability."
Reference:
Perspective
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Chad A. Kliger, MD, MS, FACC, FSCAI
Patients with small annuli represent an important patient population. In prior trials, they encompassed nearly one-third of patients enrolled. In this trial, nearly 90% of patients were female.
Historically, we know that higher mean echo gradients translate to worse outcomes in terms of mortality and quality of life. This trial now provides more evidence into the known design differences between the two valves, one being supra-annular and the other being intra-annular, and how this translates into hemodynamic differences and short-term clinical outcomes.
The trial shows us that using the VARC definition of bioprosthetic valve dysfunction that there are confirmed differences at 1 year: 9.4% for the self-expanding valve and 41.6% for the balloon-expandable valve. These confirmed hemodynamic differences do not, however, translate into a difference in clinical outcomes at 1 year — death, disabling stroke or rehospitalization.
The echocardiographic data are striking, with mean gradients for the self-expandable valve of 7.7 mm Hg and for the balloon-expandable valve of 15.7 mm Hg and with effective orifice area 1.99 cm2 vs. 1.5 cm2, respectively. However, we do not have the important invasive hemodynamic data for comparison that we all know exists in the catheterization laboratory.
This trial will force us to continue to have the conversation regarding valve selection in this patient population. It is not clear to me whether this will change valve selection or practice patterns, but it is clear that more long-term data about this issue and more information on how it impacts our patients regarding quality of life are needed. It will also force us to integrate in patients with small annuli this concept of lifetime management, especially as we treat younger and younger patients.
Perspective
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Suzanne J. Baron, MD, MSc, FSCAI
The SMART trial was one of the first head-to-head studies of two of the most widely used TAVR implants in patients with severe aortic stenosis and small annuli and it enrolled 87% women, which is an amazing feat for a cardiac device trial since women are historically underrepresented in CV studies.
Both valve platforms performed well at 1 year with no significant differences in CV mortality, stroke or hospitalization for HF. In terms of hemodynamics, the self-expanding valve demonstrated better hemodynamic performance when compared with the balloon-expandable valve; however, these differences did not translate into clinical differences at 1 year.
Whether clinical differences emerge in the future will be very important to know, as that will offer definitive information regarding the clinical importance of these echocardiographic findings in this patient population. Until then, I will continue to factor in valve hemodynamics, in addition to other anatomic and clinical considerations, when engaging in preprocedural planning for my patients with aortic stenosis and small annuli.
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Herrmann HC, et al. Joint American College of Cardiology/New England Journal of Medicine Late-breaking clinical trials III. Presented at: American College of Cardiology Scientific Session; April 6-8, 2024; Atlanta.
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