When recommending both surgical aortic valve replacement (SAVR) and transcatheter aortic valve replacement (TAVR) as options for older patients with aortic stenosis, current clinical guidelines do not account for sex, aortic annular size, and prosthetic valve hemodynamics. Study data have suggested that TAVR may be a superior option for aortic stenosis patients with small aortic annulus, who are often female. Multiple studies have shown improved outcomes for TAVR in female patients; however, there have been low numbers of women enrolled in heart valve trials.

The investigator-initiated, prospective, randomized controlled VIVA trial sought to compare the hemodynamic and clinical outcomes of TAVR and SAVR in patients with severe aortic stenosis and small aortic annulus (mean diameter <23 mm, minimal diameter ≤21.5 mm). The VIVA trial was presented by Dr. Josep Rodés-Cabau on October 26^th during a late-breaking clinical trials session at the TCT 2023 meeting in San Francisco, California.

VIVA included 15 centers in Canada, Europe, and Brazil, and patients were randomized in a 1:1 fashion to TAVR or SAVR. Follow-up occurred at 30 days, 60 days, 1 year, and yearly out to 5 years with echocardiography data evaluated by a core lab at 60 days. The 60-day echocardiography timing was important to avoid penalizing the surgical group, noted Dr. Rodés-Cabau. Patients included in the trial were ≥65 years of age and eligible for TAVR or SAVR by a structural heart team evaluation. Patients had no additional or prior valve disease, or extensive coronary artery disease with a SYNTAX score >32. The primary endpoint was impaired valve hemodynamics at 60 days, defined as severe prosthesis-patient mismatch and moderate-severe aortic regurgitation using VARC-2 definitions, as evaluated by echocardiography. Secondary endpoints included death, stroke, major bleeding, new-onset atrial fibrillation, permanent pacemaker implantation, and cardiac rehospitalization at 30 days and at follow-up.

Transcatheter valves included in the VIVA trial were the Sapien 3/Ultra (Edwards Lifesciences), Evolut R/PRO/PRO+/FX (Medtronic), and Acurate neo/neo2 (Boston Scientific). Any surgical valve type was approved for use and aortic root intervention was left to the criteria of the surgeon. The study was powered to show the superiority of TAVR for the primary outcome, with an initial sample size estimate of 300 patients. The trial experienced slow enrollment due to the COVID-19 pandemic and halted enrollment after 156 patients, with the final study at 151 patients, nearly equally randomized to TAVR or SAVR. The vast majority of the patients were women (93%) at mild to intermediate surgical risk. Mean and minimal annulus diameters were 21 mm and 19 mm, respectively.

Transcatheter system use was divided by balloon-expandable (40.8%) and self-expandable (59.2%) valves, while most patients in the surgical group received a stented surgical valve (78.9%) and sutureless surgical valve (21.1%). Medium valve size in the transcatheter group was 23 mm versus 21 mm in the surgical cohort.

Thirty-day outcomes showed no significant differences between TAVR and SAVR in terms of mortality (~1% in each group) and stroke, but did show a higher rate in the surgical group for major bleeding events (not statistically significant, P=.09) and new-onset atrial fibrillation (P<.01). No other clinical differences were found. At 60 days, valve performance was evaluated, and no significant differences were found between the two groups in terms of mean maximal transvalvular gradients, as well as aortic valve areas, following the procedure. Regarding the primary outcome of the study, which was impaired valve performance at 60 days, there was no statistically significant difference between TAVR and SAVR (5.6% and 10.3%, respectively). The vast majority of patients had no or trace aortic regurgitation. When prosthesis-patient mismatch was recalculated from a VARC-2 to a VARC-3 definition (VARC-3 considers body mass index), the rates were even lower in both groups, 4.2% in the TAVR group versus 7.4% in the SAVR group, with numerical differences nonsignificant between the two groups.

Follow-up outcomes at the median (1-4 years) of 2 years showed the only difference between groups was the rate of new-onset atrial fibrillation, with 10.4% in the TAVR group and 31.1% in the SAVR group (P<.01), similar to the 30-day outcomes. Functional status and quality of life data improved in both groups, with no differences at 1- and 2-year follow-up. However, TAVR patients had a quicker recovery, which translated into higher functional status and quality of life at 30-day follow-up as compared to SAVR.

Limitations of the VIVA trial include its limited sample size and early termination, along with lower-than-expected rates of prosthesis-patient mismatch, particularly in the surgical group, which may have underpowered the primary endpoint results. In addition, the trial had no clinical event adjudication committee.

Dr. Rodés-Cabau concluded by noting that the vast majority of the low-to-intermediate risk patients with a small aortic annulus in the VIVA trial were women. “To the best of our knowledge,” he said, “This is probably the first trial in the heart valve field enrolling more than 90% women patients as a study population.” Valve hemodynamic outcomes showed no differences between TAVR and SAVR groups, and there were low rates of prosthesis-patient mismatch in both groups, as evaluated by Doppler echocardiography at 60 days. No significant differences were found between TAVR and SAVR in 1- and 2-year clinical outcomes, except for a higher rate of new-onset atrial fibrillation in the surgical group. “TAVR and SAVR represent a valid alternative for treating patients with aortic stenosis and small aortic annulus,” concluded Dr. Rodés-Cabau. “Treatment selection should likely be individualized according to baseline characteristics, additional anatomical risk factors, and patient preference.”

Simultaneous to its presentation at TCT 2023, VIVA trial results were published in Circulation.

View Dr. Rodés-Cabau's slides here. 

Keep reading about the latest in TAVR research:

TCT 2023 Newsroom

TVT 2023: The Structural Heart Summit Newsroom