Transcatheter aortic valve replacement (TAVR): expanding indications to low-risk patients

Impact of nickel-titanium super-elastic material properties on the mechanical performance of self-expandable transcatheter aortic valves

Self-expandable transcatheter aortic valves (TAVs) elastically resume their initial shape when implanted without the need for balloon inflation by virtue of the nickel-titanium (NiTi) frame super-elastic properties. Experimental findings suggest that NiTi mechanical properties can vary markedly because of a strong dependence on the chemical composition and processing operations. In this context, this study presents a computational framework to investigate the impact of the NiTi super-elastic material properties on the TAV mechanical performance. Finite element (FE) analyses of TAV implantation were performed considering two different TAV frames and three idealized aortic root anatomies, evaluating the device mechanical response in terms of pullout force magnitude exerted by the TAV frame and peak maximum principal stress within the aortic root. The widely adopted NiTi constitute model by Auricchio and Taylor (1997) was used. A multi-parametric sensitivity analysis and a multi-objective optimization of the TAV mechanical performance were conducted in relation to the parameters of the NiTi constitutive model. The results highlighted that: five NiTi material model parameters (E_A, σ_tL^S, σ_tU^S, σ_tU^E and σ_cL^S) are significantly correlated with the FE outputs; the TAV frame geometry and aortic root anatomy have a marginal effect on the level of influence of each NiTi material parameter; NiTi alloy candidates with pareto-optimal characteristics in terms of TAV mechanical performance can be successfully identified. In conclusion, the proposed computational framework supports the TAV design phase, providing information on the relationship between the super-elastic behavior of the supplied NiTi alloys and the device mechanical response.

Impact of implantation technique on conduction disturbances for TAVR with the self-expanding portico/navitor valve

BACKGROUND

Use of a right-left (R-L) cusp overlap view for transcatheter aortic valve replacement (TAVR) with self-expanding valves has recently been proposed aiming to reduce permanent pacemaker implantation (PPMI). An objective, data-driven explanation for this observation is missing.

AIMS

To assess the impact of different implantation techniques on the risk of PPMI following TAVR with the Portico/NavitorTM transcatheter heart valve (THV; Abbott).

METHODS

A TAVR-population treated with Portico/NavitorTM had the THV implanted in a right versus left anterior oblique (RAO/LAO) fluoroscopic view with no parallax in the delivery system. The impact of these different implantation views on the spatial relationship between THV and native aortic annulus and the risk of conduction disturbances and PPMI after TAVR was studied.

RESULTS

A total of 366 matched TAVR patients were studied: 183 in the RAO group and 183 in the LAO group. The degree of aortic annulus plane tilt was significantly smaller in the RAO versus LAO group (median: 0° vs. 23°, p < 0.001), with no plane tilt in 105 out of 183 cases (57.3%) in the RAO group. At 30 days after TAVR, the overall PPMI and guideline-directed PPMI rates were 12.6% versus 18.0% (p = 0.15) and 8.2% versus 15.3% (p = 0.04) in the RAO versus LAO group, respectively.

CONCLUSIONS

Use of a R-L cusp overlap (RAO-caudal) view for implantation of the Portico/NavitorTM valve results in less tilt of the native aortic annulus plane and a clear trend toward a lower 30-day PPMI rate as compared to TAVR using the conventional LAO implantation view.

Efficacy and Safety of Emergent Transcatheter Aortic Valve Implantation in Patients with Acute Decompensated Aortic Stenosis: Systematic Review and Meta-Analysis

Introduction

The aim of this systematic review and meta-analysis was to investigate the efficacy and safety of emergent transcatheter aortic valve implantation (TAVI) in patients with decompensated aortic stenosis (AS) by comparing the clinical outcomes with the patients who had received the elective TAVI.

Methods

By searching PubMed, EMBASE, and Cochrane databases, we obtained the studies comparing the clinical outcomes of emergent TAVI and elective TAVI. Finally, 14 studies were included.

Results

A total of 14 eligible articles with 73,484 patients were included in this meta-analysis. Emergent TAVI was associated with a higher mortality during hospitalization (HR 2.09, 95% CI [1.39 to 3.14]), 30 days (HR 2.29, 95% CI [1.69 to 3.10]), and 1 year (HR 1.96, 95% CI [1.55 to 2.49]). Consistently, the incidence of acute kidney injury (AKI) (RR 2.48, 95% CI [1.85 to 3.32]), dialysis (RR 2.37, 95% CI [1.95 to 2.88]), bleeding (RR 1.62, 95% CI [1.27 to 2.08]), major bleeding (RR 1.05, 95% CI [1.00 to 1.10]), and 30-day rehospitalization (RR 1.30, 95% CI [1.07, 1.58]) were more common in patients receiving emergent TAVI. No statistical differences were found in the occurrence rate of vascular complications (RR 1.11, 95% CI [0.90, 1.36]), major vascular complications (RR 1.14, 95% CI [0.52, 2.52]), permanent pacemaker (PPM) placement (RR 1.05, 95% CI [0.99, 1.11]), cerebrovascular events (RR 1.11, 95% CI [0.98, 1.25]), moderate to severe paravalvular leakage (PVL) (RR 1.23, 95% [CI 0.94 to 1.61]), and device success (RR 0.99, 95% CI [0.97, 1.01]).

Conclusion

Emergent TAVI is associated with some postoperative complications and increased mortality compared with elective TAVI. Emergent TAVI should be implemented cautiously and individually.

Propensity-matched comparison of balloon-expandable and self-expanding valves for transcatheter aortic valve replacement in a Chinese population

Background

Balloon-expandable valves (BEV) and self-expanding valves (SEV) for transcatheter aortic valve replacement (TAVR) have shown promising results in Western populations. Herein, we comparatively evaluated their hemodynamics and early clinical outcomes in a Chinese population.

Methods

One hundred seventy-eight patients with symptomatic aortic stenosis who had undergone transfemoral TAVR using SEV (n=153; Venus-A, 97; VitaFlow, 56) or BEV (n=25; Sapien3) from September 2020 to April 2021 were retrospectively enrolled, and 25 pairs were propensity-score matched for 10 baseline variables. The primary study outcomes were aortic valve hemodynamics and postoperative complications at discharge and 3-month follow-up.

Results

TAVR was successful in all patients. Compared with SEV group, the BEV group had similarly distributed baseline characteristics, procedural time, hospital stay, new pacemaker implantation, and paravalvular regurgitation grade. We also observed that the BEV group had lower rates of balloon pre-dilation (60% vs. 92%, P=0.018), post-dilation (0 vs. 20%, P=0.050) and second valve implantation (0 vs. 24%, P=0.022); higher mean transaortic gradient (14.3±6.1 vs. 10.8±4.9, P=0.030) and proportion of patients with elevated gradients (20% vs. 0, P=0.050) at discharge; and similar rehospitalization, mean transaortic gradient, new pacemaker implantation, and paravalvular regurgitation grade than the SEV group at the 3-month follow-up. There were no deaths in either group. However, the proportion of patients with elevated gradients in SEV group was higher at 3 months than before discharge (24% vs. 0, P=0.022).

Conclusions

BEV and SEV for transfemoral TAVR appear comparably safe and effective, with high device success and favorable 3-month clinical outcomes. However, the transaortic gradient and new pacemaker implantation in the SEV group increased during follow-up, warranting larger studies with longer-term follow-up.