Background:
Transcatheter aortic valve implantation (TAVI) in patients with small aortic annuli is challenging due to the associated risks of patient–prosthesis mismatch and higher post-procedural gradients. Although supra-annular valve designs are believed to offer better haemodynamic performance than intra-annular prostheses, there is limited real-world data.
Objectives:
This retrospective, single-centre study aimed to compare the procedural characteristics, in-hospital outcomes, and early echocardiographic results of intra-annular and supra-annular TAVI prostheses in patients with small annuli (annular diameter <23 mm and annular area <430 mm²).
Methods and results:
Between June 2024 and October 2025, 204 consecutive patients (mean age 81.9 ± 6 years; 89.2% female) with small annuli underwent TAVI (98.5% transfemoral). Supra-annular valves were implanted in 147 patients (80 self-expandable Acurate Neo 2/Acurate Prime and 67 self-expandable Evolut FX/FX+), and intra-annular valves in 57 patients (24 balloon-expandable Edwards Sapien 3 Ultra/Resilia and 35 self-expandable Navitor Vision). Baseline characteristics were comparable, except for a higher prevalence of coronary artery disease (34% vs. 56%; p = 0.01) and atrial fibrillation rates (42.1% vs. 27.2%; p = 0.04) in the intra-annular group. Pre-existing pacemakers were more prevalent among intra-annular patients (14% vs. 5.4%; p = 0.04).
Pre-dilatation was performed more often in supra-annular cases (99.3% vs. 70.2%; p < 0.001), primarily due to the lower requirement for pre-dilatation with the balloon-expandable device. Technical success was 100% in both groups. Post-procedural mean gradients were comparable, though there was a trend towards a smaller effective orifice area with intra-annular valves (1.71 cm² vs. 1.85 cm²; p = 0.054). No moderate or severe paravalvular leak occurred and no patient–prosthesis mismatch was observed. The rate of new pacemaker implantation was 3.5% (intra-annular) versus 6.8% (supra-annular). Device success was significantly higher in the supra-annular group (96.6% vs. 89.5%; p = 0.044). Follow-up echocardiography, which was available for 111 patients (54.7%), showed no significant difference in bioprosthetic valve dysfunction (4% vs. 2.3%, p = 0.54) with a median follow-up time of 113 days.
A subanalysis limited to the currently available self-expanding prostheses (Evolut FX/FX+, n = 67; Navitor Vision, n = 35) showed that baseline characteristics were comparable, except for higher rates of coronary artery disease and atrial fibrillation in the self-expandable intra-annular group. Procedural outcomes, gradients and effective orifice areas were similar, with two cases of valve thrombosis occurring in the self-expandable supra-annular group.
Conclusion:
In patients with small annuli, supra-annular TAVI prostheses demonstrated higher device success rates and a trend towards a larger effective orifice area compared to intra-annular designs. There were no significant differences in terms of gradients, paravalvular leak, patient-prosthesis mismatch or clinical outcomes. These findings support the feasibility of both valve concepts in small annuli, with the potential haemodynamic advantages of supra-annular designs requiring confirmation in larger, prospective trials.
