Long-Term Durability of Transcatheter Heart Valves: Insights From Bench Testing to 25 Years

Rethinking mechanical heart valves in the aortic position: new paradigms in design and testing

Bileaflet mechanical heart valves (MHV) remain a viable option for aortic valve replacement, particularly for younger patients and patients from low- and middle-income countries and underserved communities. Despite their exceptional durability, MHV recipients are at increased risk of thromboembolic complications. As such, the development of the next generation of MHVs must prioritize improved thromboresistance and aim for independence from anticoagulant therapy. However, innovation in MHV design faces several challenges: strict performance and biocompatibility requirements, limited understanding of the mechanisms underlying MHV thrombosis, and a lack of effective testing methodologies to assess how design variations impact both hemodynamic performance and thrombogenicity of MHVs. This paper reviews the emerging paradigms in MHV design, materials and surface modifications that may inspire the development of a new generation of MHVs for aortic valve replacement. We also discuss challenges and opportunities in developing experimental and numerical approaches to achieve a more comprehensive understanding of MHV flow features and the mechanisms of flow-induced blood clotting.

3D printing of heart valves

3D printing technologies have the potential to revolutionize the manufacture of heart valves through the ability to create bespoke, complex constructs. In light of recent technological advances, we review the progress made towards 3D printing of heart valves, focusing on studies that have utilised these technologies beyond manufacturing patient-specific moulds. We first overview the key requirements of a heart valve to assess functionality. We then present the 3D printing technologies used to engineer heart valves. By referencing International Organisation for Standardisation (ISO) Standard 5840 (Cardiovascular implants - Cardiac valve prostheses), we provide insight into the achieved functionality of these valves. Overall, 3D printing promises to have a significant positive impact on the creation of artificial heart valves and potentially unlock full complex functionality.

Transcatheter Aortic Valve Replacement as a bridge to minimally invasive endoscopic mitral valve surgery in Elderly Patients in the era of ERAS and Fast Track TAVI concepts

In this bicentric study, we report the outcomes of combined transcatheter aortic valve replacement combined with minimally invasive mitral valve surgery. We included a cohort of six patients (79.6 ± 3.2 years, 83% women) with high-risk profiles and deemed to be non-operable with combined mitral and aortic valvular disease. All patients had unsuitable anatomies for transcatheter mitral valve edge-to-edge repair (TEER). Moreover, most of the patients (5/6) suffered a combined aortic valve lesion, which complicates the efficiency of cardioplegia in the case of CBP through minimally invasive incisions. The first stage was implanting a TAVI valve to achieve aortic valve competency and hence facilitate the infusion of cardioplegia after clamping the aorta during endoscopic mitral valve surgery. After one week, we performed the minimally invasive mitral valve repair. Most patients (n = 5; 83%) underwent successful endoscopic mitral valve repair. Intraoperatively, the mean ischemic time was 42 min, and the total bypass time was 72 min. Postoperatively, the mean intubation time was 0 h. Postoperative complications included reoperation for bleeding in one patient (16.7%) and a new heart block requiring pacemaker implantation in one patient (16.7%). There was neither in-hospital mortality nor 1-year mortality.

Transcatheter Aortic Valve Replacement: Current Status and Future Indications

In the past two decades, transcatheter aortic valve replacement (TAVR) has transformed the management of aortic stenosis and has become the standard of care regardless of surgical risk levels. Advances in transcatheter valve design across newer generations, improved imaging, greater operator expertise, and technical enhancements have collectively contributed to increased safety and a decline in procedural complications over this timeframe. The application of TAVR has progressively expanded to include younger patients with lower risks, who have longer life expectancies. This article offers an up-to-date review of the latest innovations in transcatheter delivery systems, devices, and its possible future indications.

Transcatheter Aortic-Valve Replacement in Low-Risk Patients at Five Years

BACKGROUND

A previous analysis in this trial showed that among patients with severe, symptomatic aortic stenosis who were at low surgical risk, the rate of the composite end point of death, stroke, or rehospitalization at 1 year was significantly lower with transcatheter aortic-valve replacement (TAVR) than with surgical aortic-valve replacement. Longer-term outcomes are unknown.

METHODS

We randomly assigned patients with severe, symptomatic aortic stenosis and low surgical risk to undergo either TAVR or surgery. The first primary end point was a composite of death, stroke, or rehospitalization related to the valve, the procedure, or heart failure. The second primary end point was a hierarchical composite that included death, disabling stroke, nondisabling stroke, and the number of rehospitalization days, analyzed with the use of a win ratio analysis. Clinical, echocardiographic, and health-status outcomes were assessed through 5 years.

RESULTS

A total of 1000 patients underwent randomization: 503 patients were assigned to undergo TAVR, and 497 to undergo surgery. A component of the first primary end point occurred in 111 of 496 patients in the TAVR group and in 117 of 454 patients in the surgery group (Kaplan-Meier estimates, 22.8% in the TAVR group and 27.2% in the surgery group; difference, -4.3 percentage points; 95% confidence interval [CI], -9.9 to 1.3; P = 0.07). The win ratio for the second primary end point was 1.17 (95% CI, 0.90 to 1.51; P = 0.25). The Kaplan-Meier estimates for the components of the first primary end point were as follows: death, 10.0% in the TAVR group and 8.2% in the surgery group; stroke, 5.8% and 6.4%, respectively; and rehospitalization, 13.7% and 17.4%. The hemodynamic performance of the valve, assessed according to the mean (±SD) valve gradient, was 12.8±6.5 mm Hg in the TAVR group and 11.7±5.6 mm Hg in the surgery group. Bioprosthetic-valve failure occurred in 3.3% of the patients in the TAVR group and in 3.8% of those in the surgery group.

CONCLUSIONS

Among low-risk patients with severe, symptomatic aortic stenosis who underwent TAVR or surgery, there was no significant between-group difference in the two primary composite outcomes. (Funded by Edwards Lifesciences; PARTNER 3 ClinicalTrials.gov number, NCT02675114.).

Transcatheter Tricuspid Valve Replacement: Case Selection, Technical Considerations, and Procedural Planning

Tricuspid regurgitation (TR) is a highly prevalent valve disorder in the US, with prevalence increasing with age. Without treatment, severe TR carries a poor prognosis. Tricuspid valve (TV) surgery is recommended for patients with severe TR undergoing left-sided valve surgery. Transcatheter TV repair or transcatheter TV replacement are potential options for patients who are not surgical candidates. A few small studies have demonstrated the feasibility and efficacy of transcatheter TV repair in patients with severe symptomatic TR. Careful patient selection by assessing tricuspid valve anatomy, right ventricular and pulmonary hemodynamics, candidacy for anticoagulation, comorbid conditions, and frailty is key to procedural success. Transcatheter TV repair can be performed via the transjugular or transfemoral access, and requires a large-caliber sheath (up to 45 Fr) and delivery system, particularly with dilated tricuspid annulus due to right ventricular enlargement. Multimodality imaging is essential for diagnosing TR severity, defining valve anatomy, and comprehensive functional assessment of the tricuspid valve, right atrium, and right ventricle. Several prosthetic valves, including the EVOQUE system, NaviGate system, Intrepid valve, and Cardiovalve, are currently being investigated in clinical trials.

Outcomes of SAPIEN 3 Transcatheter Aortic Valve Replacement Compared With Surgical Valve Replacement in Intermediate-Risk Patients

BACKGROUND

Previous studies demonstrated transcatheter aortic valve replacement (TAVR) with an earlier generation balloon-expandable valve to be noninferior to surgical aortic valve replacement (SAVR) for death and disabling stroke in intermediate-risk patients with symptomatic, severe aortic stenosis at 5 years. However, limited long-term data are available with the more contemporary SAPIEN 3 (S3) bioprosthesis.

OBJECTIVES

The aim of this study was to compare 5-year risk-adjusted outcomes in intermediate-risk patients undergoing S3 TAVR vs SAVR.

METHODS

Propensity score matching was performed to account for baseline differences in intermediate-risk patients undergoing S3 TAVR in the PARTNER 2 (Placement of Aortic Transcatheter Valves) S3 single-arm study and SAVR in the PARTNER 2A randomized clinical trial. The primary composite endpoint consisted of 5-year all-cause death and disabling stroke.

RESULTS

A total of 783 matched pairs of intermediate-risk patients with severe aortic stenosis were studied. There were no differences in the primary endpoint between S3 TAVR and SAVR at 5 years (40.2% vs 42.7%; HR: 0.87; 95% CI: 0.74-1.03; P = 0.10). The incidence of mild or greater paravalvular regurgitation was more common after S3 TAVR. There were no differences in structural valve deterioration-related stage 2 and 3 hemodynamic valve deterioration or bioprosthetic valve failure.

CONCLUSIONS

In this propensity-matched analysis of intermediate-risk patients, 5-year rates of death and disabling stroke were similar between S3 TAVR and SAVR. Rates of structural valve deterioration-related hemodynamic valve deterioration were similar, but paravalvular regurgitation was more common after S3 TAVR. Longer-term follow-up is needed to further evaluate differences in late adverse clinical events and bioprosthetic valve durability. (PII S3i [PARTNER II Trial: Placement of Aortic Transcatheter Valves II - S3 Intermediate], NCT03222128; PII A (PARTNER II Trial: Placement of Aortic Transcatheter Valves II - XT Intermediate and High Risk], NCT01314313).

Two cases of sudden leaflet dehiscence after transcatheter aortic valve replacement

BACKGROUND

Transcatheter aortic valve replacement (TAVR) has caused a paradigm shift in the treatment of severe aortic stenosis. Although less invasive and good early results of TAVR have been reported, the long-term durability of the transcatheter aortic valve is still unclear.

CASE PRESENTATION

We performed an emergent surgical aortic valve replacement (SAVR) for two cases of acute heart failure due to sudden transcatheter aortic valve dehiscence after 7 or 6 years of primary TAVR. In both cases, transthoracic echocardiography revealed severe transvalvular regurgitation of the transcatheter aortic valve. Intraoperative findings revealed dehiscence on both sides of the anatomical non-coronary cusp without evident signs of degeneration, such as thickening, calcification, or infection. The postoperative course of the cases was uneventful, and the patients were discharged home on days 20 and 48 after the reoperation.

CONCLUSIONS

Although the cause of the valvular disease is unknown, we are seriously concerned that the number of similar cases will increase in the future. We should be cautious in expanding the application of TAVR without evidence of long-term safety.

Aortic Valve Replacement Rates in Australia from 2004 to 2019

BACKGROUND

Several surgical and percutaneous treatments are available for patients with aortic valve disease.

AIM

Our aim is to establish whether trends in aortic valve replacements (AVR) in Australia reflect recent evidence.

METHODS

Using Australian Institute of Health and Welfare data, this study counted all AVR and balloon aortic valvuloplasty (BAV) procedures conducted in all Australian hospitals from 2004 to 2019. Linear regression analysis was performed to determine whether age-adjusted rates had changed over the study period.

RESULTS

There were 80,883 AVRs performed. 66% were men and 64% were over aged 70. Absolute rates of AVR increased from 3,631 to 7,277 with a significant 22% age-adjusted rise seen (1.9% increase per year (+0.26 per 100,000 per year, 95% CI 0.19 - 0.34); p < 0.001). This trend was more pronounced in men than women and in over 80 year-olds (+0.23 per 100,000 per year, p < 0.001). Proportion of mechanical AVRs implanted fell from 38.4% to 8.6% (p<0.001). 2,683 transcatheter aortic valve implantation (TAVI) procedures were performed in 2019, representing a 52% annual increase from 2014. BAV increased from 66 procedures in 2004 to 862 in 2019.

CONCLUSION

Rates of AVR have increased significantly over the past 16 years, particularly in the elderly. Despite international guideline recommendations, fewer mechanical AVRs are being used in younger cohorts. The uptake in TAVI rates might reflect evidence that suggests it is a safe alternative, at least in the medium term. BAV has also seen a resurgence during this time period. This article is protected by copyright. All rights reserved.

Transcatheter solutions for transcatheter aortic valve replacement dysfunction: is redo transcatheter aortic valve replacement a durable option?

As transcatheter aortic valve replacement (TAVR) expands into a younger and lower risk cohort of patients, many important clinical questions are raised, including the one of overall valve durability. Bioprosthetic valve dysfunction (BVD) is a complex clinical issue, of which structural valve deterioration (SVD) is a subcategory. Similar to surgical bioprosthesis, transcatheter heart valves (THVs) can fail over the years however, data on long-term THVs durability is lacking, especially in the lower risk cohort. Surgical explant with open aortic surgery or a second THV, described as redo-TAVR, are feasible options when the first THV fails. However long-term data in these patients is even more limited. Important clinical considerations such as the mechanism(s) of THV dysfunction, the type and timing of the second procedure must be carefully considered. There are also inherently important clinical concerns regarding redo-TAVR, such as coronary access and higher post procedure gradients. In the present keynote lecture, we review the diagnosis of THV dysfunction and transcatheter options available when SVD occurs.

Transcatheter Heart Valve Downstream Fluid Dynamics in an Accelerated Evaluation Environment

Transcatheter aortic valve replacements (TAVRs) provide minimally invasive delivery of bioprosthetic heart valves (BHVs) for the treatment of aortic valve disease. While surgical BHVs show efficacy for 8-10 years, long-term TAVR durability remains unknown. Pre-clinical testing evaluates BHV durability in an ISO:5840 compliant accelerated wear tester (AWT), yet, the design and development of AWTs and their accuracy in predicting in vivo performance, is unclear. As a result of limited knowledge on AWT environment and BHV loading, durability assessment of candidate valves remains fundamentally empirical. For the first time, high-speed particle image velocimetry quantified an ISO:5840 compliant downstream AWT velocity field, Reynolds stresses, and turbulence intensity. TAVR enface imaging quantified the orifice area and estimated the flow rate. When valve area and flow rate were at their maximum during peak systole (1.49 cm² and 16.05 L/min, respectively), central jet velocity, Reynolds normal and shear stress, and turbulence intensity grew to 0.50 m/s, 265.1 Pa, 124.6 Pa, and 37.3%, respectively. During diastole, unique AWT recirculation produced retrograde flow and the directional changes created eddies. These novel AWT findings demonstrated a substantially reduced valve fully loaded period and pressure not matching in vivo or in vitro studies, despite the comparable fluid environment and TAVR motion.

The Impact of Aortic Valvular Calcium on Transcatheter Heart Valve Distortion

Objectives

To investigate the relationship between the eccentric calcification of aortic valve and transcatheter heart valve (THV) distortion and the impact of THV distortion on echo parameters and clinical outcomes.

Background

The effects of eccentric calcification of the aortic valve on the THV distortion and the relationship between THV distortion and clinical impact were not fully understood.

Methods

Patients with symptomatic severe aortic stenosis who were undergoing THV implantation were enrolled. Patients underwent preprocedural, postprocedural multislice computed tomography (MSCT), and follow-up transthoracic echocardiogram (TTE). Delta calcium score (ΔCS) is defined as the difference between the maximum and minimal calcium scores of the three cusps, while valve distortion score (VDS) is defined as the difference between the longest and shortest stent frame, as obtained using MSCT. Patients were divided into two groups according to ΔCS: “noneccentric calcification group” and “eccentric calcification group.”

Results

A total of 118 patients were enrolled (59 patients in noneccentric and 59 in eccentric calcification groups). VDS was significantly lower in the noneccentric calcification group than in the eccentric calcification group (1.31 ± 0.82 mm vs. 1.73 ± 0.76 mm, p=0.004). VDS was not associated with the degree of paravalvular leak (PVL) and aortic valvular mean pressure gradient (AVPG) at 30-day and 1-year follow-up TTE and the cumulative rates of all-cause death and rehospitalization at 2-year clinical follow-up.

Conclusions

Eccentric valvular calcification was associated with longitudinal THV distortion. However, THV distortion was not associated with PVL, AVPG, and adverse clinical events during midterm follow-up.