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SAN FRANCISCO -- One anatomic feature, typically found in women, did not make patients with severe aortic stenosis (AS) better suited for either transcatheter aortic valve replacement (TAVR) or surgery, the VIVA trial investigators found.

Among low-to-intermediate risk patients with a small aortic annulus, valve hemodynamics at 60 days did not favor either TAVR or surgical aortic valve replacement (SAVR), as there were no differences between treatments in the rate of severe prosthesis-patient mismatch (PPM; 5.6% vs 10.3%, P=0.30) and moderate-severe aortic regurgitation (AR; none in both groups).

As for clinical outcomes, 30-day rates of mortality (1.3% vs 1.4%, P=1.00) and stroke (0 vs 2.7%, P=0.24) were similar between TAVR and SAVR arms, as were 2-year mortality (9.1% vs 8.1%, P=0.89), stroke (3.9% vs 4.1%, P=0.95), and cardiac hospitalization (19.5% vs 20.3%, P=0.80).

Josep Rodés-Cabau, MD, PhD, of Quebec Heart & Lung Institute, Laval University, Quebec City, reported the VIVA results here at the Transcatheter Cardiovascular Therapeutics (TCT) meeting hosted by the Cardiovascular Research Foundation. The trial manuscript was published in .

"The results of this trial suggest that these two therapies represent a valid alternative for treating patients with AS and small aortic annulus, and treatment selection should likely be individualized according to baseline characteristics, additional anatomical risk factors, and patient preference," Rodés-Cabau told the audience.

This report thus contradicts prior work, based on observational studies and substudies from randomized trials, that had suggested superior prosthetic valve hemodynamics after TAVR in patients with small annuli. This anatomic feature is currently not mentioned as a deciding factor in aortic valve guidelines.

At a TCT press conference, panelist Yousif Ahmad, MD, PhD, of Yale School of Medicine in New Haven, Connecticut, commented that longer-term data are still needed when it comes to assessing valve function in small annuli. Never mind 2 years, he said -- "I think even 5-year data will be too short. We want to know what happens a decade out."

Rodés-Cabau reported that in the trial, operators had the choice among contemporary TAVR devices and surgical prosthetic valves. In the TAVR arm, 60% of patients got a self-expandable valve and 40% a balloon-expandable one; the median TAVR valve size was 23 mm. In the SAVR arm, all except one person got a bioprosthetic valve and the median valve size was 21 mm.

Notably, just 7% of the surgical arm got a preemptive aortic root enlargement. This was "very low" for Ahmad, who said patients with a small annulus at his institution would be referred to surgery for a root enlargement so that they can get a larger valve.

The press conference moderator, Roxana Mehran, MD, of Mount Sinai Health System in New York City, noted that even though surgeons often say they will do a root enlargement on these patients, this was recorded in under 5% of cases in the Society of Thoracic Surgeons (STS) database. "Seven percent is a bit higher than what the norm is," she argued, emphasizing that VIVA is therefore a trial that is relevant to real-world practice.

Rodés-Cabau nevertheless acknowledged that the VIVA study was underpowered due to a stop in enrollment at 151 people (roughly half the planned sample). This early termination was attributed to publication at the time of the low-risk trials that gave TAVR noninferiority or better when compared with SAVR.

If the trial had been sufficiently powered, then TAVR's low incidence of PPM might have turned into a statistically significant reduction, suggested Wayne Batchelor, MD, of Inova Heart and Vascular Institute in Falls Church, Virginia, another panelist.

In the small-annulus population, PPM (i.e., when a valve prosthesis's hemodynamics aren't appropriate for the patient's cardiac output requirement) normally reaches 20-40% historically, Batchelor said. Severe PPM has previously been linked to subsequent mortality and heart failure hospitalization.

The VIVA trial was conducted across 15 university hospitals in Canada, Europe, and Brazil. Participants had to meet criteria for severe AS and an aortic annulus no greater than 23 mm in diameter. This entailed passing an initial screening for aortic annulus diameter <21 mm on transthoracic echocardiography, followed by a CT confirmation of a mean aortic annular diameter <23 mm and a minimal diameter ≤21.5 mm.

The final 151-person cohort was randomized to TAVR (n=77) or SAVR (n=74). Mean age was 75 years, and 93% were women. Median STS score was 2.5% and median annulus diameter 21.1 mm.

"The 2-year mortality rate appears to be slightly higher than the <5% reported in the PARTNER 3 and Evolut Low Risk trials," study authors noted. "This may be partially related to the slightly higher surgical risk and older age of the patients included in the VIVA trial, but specific factors related to this population of women with [small aortic annuli] cannot be excluded."

Comparing valve performance in these patients is not just a question of TAVR vs SAVR, but between specific TAVR platforms.

Mehran announced that the highly anticipated -- testing two TAVR systems specifically in people with small aortic annuli -- has completed enrollment and will be presented this coming spring.

In a prior observational study of TAVR recipients with small annuli in the France-TAVI registry, there were better hemodynamic results with a self-expandable valve than a balloon-expandable one, with a signal of better clinical outcomes on top.

As for the long-term management of a small-annulus patient, Rodés-Cabau said the Sapien device with Resilia tissue technology was the most frequently used device in VIVA, and this device is designed to be enlarged later on to facilitate valve-in-valve procedures in those requiring valve reintervention.

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