Small Aortic Annulus Does Not Doom TAVR Outcomes, Three-Year Study Finds

For the growing population of elderly patients undergoing transcatheter aortic valve replacement, one anatomical feature has long haunted cardiologists: the small aortic annulus. A new post-hoc analysis of the multicenter SCOPE I randomized trial, published in Clinical Research in Cardiology, delivers a reassuring verdict on this common concern. Among more than 700 patients followed for three years, those with a small annulus fared just as well as their peers with larger annular dimensions, both in survival and in how they actually felt about their health. The finding challenges the assumption that constrained valve anatomy inevitably compromises long-term benefit from the minimally invasive procedure.

The study, led by Ottavia Cozzi and Daijiro Tomii of Bern University Hospital together with senior author Thomas Pilgrim, categorized 732 patients according to computed tomography-derived annular area, defining a small annulus as 430 square millimeters or less. This threshold is the most widely applied cut-off in the contemporary literature, and the researchers also ran sensitivity analyses using stricter definitions of 386 and 400 square millimeters. The results held firm across all definitions. In total, 323 patients, or 44.1 percent of the cohort, had a small annulus, underscoring just how frequently this anatomy appears in clinical practice.

The demographic profile of these patients was striking. More than 84 percent of those with a small annulus were women, compared with just over a third of patients with larger annuli. Women with severe aortic stenosis often present with more advanced disease and greater frailty at the time of intervention, a pattern thought to reflect later detection and delayed referral. Patients with small annuli also carried slightly higher predicted surgical risk, with a median Society of Thoracic Surgeons Predicted Risk of Mortality score of 3.8 percent versus 3.3 percent. By contrast, atrial fibrillation, obstructive coronary artery disease, and prior cardiothoracic surgery were more common among those with larger annuli, painting two distinct clinical phenotypes.

Hemodynamically, the small-annulus group did face measurable disadvantages. Thirty days after the procedure, echocardiography revealed higher mean transprosthetic gradients of 10 millimeters of mercury compared with 8 in the larger-annulus group, and a higher prevalence of residual gradients exceeding 20 millimeters of mercury. The effective orifice area and its indexed value were both significantly smaller, translating into a higher rate of moderate or severe prosthesis-patient mismatch, a condition in which the implanted valve is too small relative to the patient’s body size to permit unimpeded blood flow. In theory, such suboptimal forward flow should reduce exercise capacity and erode quality of life.

Yet the clinical data told a different story. At three years, all-cause mortality was actually numerically lower in the small-annulus group, at 18.6 percent versus 25.4 percent, a difference that was not statistically significant after adjustment. Cardiovascular death and hospitalization for heart failure were likewise comparable between groups. The researchers went a step further by evaluating an integrated patient-centered endpoint: being alive with good health status, defined as a Kansas City Cardiomyopathy Questionnaire overall summary score of at least 75 without a decline of more than 10 points from baseline. At three years, 46.5 percent of small-annulus patients achieved this demanding benchmark, compared with 43.2 percent of those with larger annuli, an odds ratio of 0.95 that was firmly within the range of chance.

Patient-reported health status itself followed a similar trajectory in both groups. Baseline Kansas City Cardiomyopathy Questionnaire scores were nearly identical, hovering in the mid-50s, and rose sharply after valve replacement in both cohorts. Although patients with small annuli experienced a slightly smaller early improvement at 30 days, ordinal analysis showed that more than 70 percent of patients in both groups enjoyed at least mild improvement at one and three years. By the three-year mark, median overall summary scores remained in the low 80s for both groups, indicating sustained, meaningful recovery in symptoms, physical limitation, and quality of life after the procedure.

The most provocative finding emerged from an exploratory factorial analysis examining the interplay between annular size and valve type. The SCOPE I trial had randomized patients to either the self-expanding ACURATE Neo from Boston Scientific or the balloon-expandable SAPIEN 3 from Edwards Lifesciences. When the investigators crossed annular size with valve type, a statistically significant interaction appeared for the patient-centered outcome. Patients with a small annulus treated with the balloon-expandable SAPIEN 3 had a lower probability of being alive with good health status at three years, with a relative risk of 0.59 and a p-value for interaction of 0.004. No such difference between valve types was seen in patients with larger annuli.

The mechanism behind this interaction remains speculative. The authors note that the intra-annular leaflet position of the balloon-expandable platform, together with differences in skirt design, frame expansion within a constrained annulus, and commissural alignment, may yield less favorable forward hemodynamics than a supra-annular design. They also point to the randomized SMART trial, which compared the SAPIEN 3 with the supra-annular Evolut valve specifically in small-annulus patients and found better echocardiographic valve performance and more frequent health-status improvement with the self-expanding device, though without differences in hard clinical endpoints. The researchers caution that echocardiography may systematically favor supra-annular devices due to measurement methodology, and that the apparent hemodynamic superiority should not be equated with definitive clinical advantage.

Several caveats temper the conclusions. As a post-hoc analysis, the study was not powered to detect differences by annular size, and all interaction analyses are exploratory. Residual imbalances persisted in sex, left ventricular ejection fraction, and serum creatinine even after propensity-based overlap weighting. Questionnaire data were available only for survivors who completed follow-up, and objective exercise testing was not systematically collected, leaving open the possibility of subtle functional differences. The advanced age of the cohort, with a median of 83 years, may also have blunted the functional impact of suboptimal hemodynamics, and the findings may not extend to younger, more active patients treated at lower surgical risk.

Practical implications nonetheless emerge. A small aortic annulus, present in more than 40 percent of TAVR candidates and overwhelmingly among women, should not be regarded as a barrier to excellent outcomes. The hemodynamic penalties visible on echocardiography do not translate into worse survival or diminished quality-of-life recovery over three years in well-selected patients. At the same time, the valve-type interaction hints that device selection may matter more in this anatomy than previously appreciated, a hypothesis that will require confirmation in adequately powered studies with contemporary devices, particularly as the ACURATE platform has since been withdrawn from clinical use and newer iterations of balloon-expandable valves have shown improved hemodynamics in smaller sizes. For now, the message to patients and physicians alike is one of cautious reassurance.

Subject of Research: Impact of small aortic annulus size on clinical and quality-of-life outcomes after transcatheter aortic valve replacement

Article Title: Relationship between a small aortic annulus and clinical and quality-of-life outcomes in patients undergoing TAVR

Article References: Cozzi, O., Tomii, D., Lanz, J., Heg, D., Thiele, H., Kim, W.-K., Joner, M., Thilo, C., Toggweiler, S., Prendergast, B., Windecker, S., Pilgrim, T., & the SCOPE I Investigators (2026). Relationship between a small aortic annulus and clinical and quality-of-life outcomes in patients undergoing TAVR. Clinical Research in Cardiology. https://doi.org/10.1007/s00392-026-03025-y

Image Credits: AI Generated

DOI: 10.1007/s00392-026-03025-y

Keywords: TAVR, aortic stenosis, small aortic annulus, prosthesis-patient mismatch, Kansas City Cardiomyopathy Questionnaire, transcatheter heart valve, SCOPE I trial, patient-reported outcomes, valve hemodynamics, cardiology, heart valve replacement, clinical outcomes