Impact of Transcatheter Aortic Valve Durability on Life Expectancy in Low-Risk Patients With Severe Aortic Stenosis

Transcatheter aortic valve replacement: Past, present, and future

Transcatheter aortic valve replacement (TAVR) has emerged as a ground-breaking, minimally invasive alternative to traditional open-heart surgery, primarily designed for elderly patients initially considered unsuitable for surgical intervention due to severe aortic stenosis. As a result of successful large-scale trials, TAVR is now being routinely applied to a broader spectrum of patients. In deciding between TAVR and surgical aortic valve replacement, clinicians evaluate various factors, including patient suitability and anatomy through preprocedural imaging, which guides prosthetic valve sizing and access site selection. Patient surgical risk is a pivotal consideration, with a multidisciplinary team making the ultimate decision in the patient's best interest. Periprocedural imaging aids real-time visualization but is influenced by anaesthesia choices. A comprehensive postprocedural assessment is critical due to potential TAVR-related complications. Numerous trials have demonstrated that TAVR matches or surpasses surgery for patients with diverse surgical risk profiles, ranging from extreme to low risk. However, long-term follow-up data, particularly in low-risk cases, remains limited, and the applicability of published results to younger patients is uncertain. This review delves into key TAVR studies, pinpointing areas for potential improvement while delving into the future of this innovative procedure. Furthermore, it explores the expanding role of TAVR technology in addressing other heart valve replacement procedures.

In silico fatigue optimization of TAVR stent designs with physiological motion in a beating heart model

BACKGROUND AND OBJECTIVE

The rapid expansion of TAVR to younger, low-risk patients raises concerns regarding device durability. Necessarily, extended stent lifetime will become more critical for new generation devices. In vitro methods commonly used for TAVR stent fatigue testing exclude the effects of the beating heart. We present a more realistic in silico stent fatigue analysis utilizing a beating heart model in which TAVR stents experience complex, nonuniform dynamic loading.

METHODS

Virtual TAVR deployments were simulated in the SIMULIA Living Heart Human Model of a beating heart using stent models of the self-expandable nitinol 26-mm CoreValve and Evolut R devices, and a 27-mm PolyV-2. Stent deformation was monitored over three cardiac cycles, and fatigue resistance was evaluated for the nitinol stents using finite element analysis via ABAQUS/Explicit. The average strain and strain amplitude of each stent element were tracked, and established thresholds were applied to determine potential fatigue failure. Fatigue performance of control stents was compared to parametrically modified models with a 20% increase or decrease in strut width.

RESULTS

Stents with reduced strut width applied lower radial force against the contracting myocardium of the beating heart, resulting in larger displacements and higher strain values. Formulas relating in vivo strain to stent design do not account for this. In all models, there were elements in which strains exceeded fatigue failure. The PolyV-2 stent had far fewer failing elements since its struts were optimized to reduce the strain in stent joints, achieving better fatigue resistance in the stent crown and waist elements. Different stent sections showed markedly different fatigue resistance due to the varying loading conditions.

CONCLUSIONS

Our analysis indicates that previous studies underestimate strain amplitudes that may cause stent failure. This study demonstrates the utility of advanced in silico analysis of devices deployed within a beating heart that mimics in vivo loading, offering a cost-effective alternative to human or animal trials and establishing a platform to assess the impact of device design on device durability. The limited fatigue life of TAVR stents indicated here highlights a clinical complication that may eventually develop as younger, lower-risk TAVR patients, age.

Radiation-Induced Aortic Stenosis: An Update on Treatment Modalities

The adverse effects of radiation therapy for cancer are well described and can include a wide array of cardiac complications. Radiation-induced aortic stenosis (AS) is an increasingly recognized entity that poses particular therapeutic challenges. Several retrospective studies comparing the outcomes after transcatheter aortic valve replacement (TAVR) vs those after surgical aortic valve replacement patients with radiation-induced AS have found a trend toward decreased mortality and fewer major complications with TAVR. Surgical aortic valve replacement is associated with increased mortality in patients with radiation-induced AS compared with patients without a history of prior radiation. TAVR has been shown to be a safe and effective alternative in patients with radiation-induced AS, with safety similar to that for patients who have not received prior radiation. However, rare and unexpected complications may occur after TAVR from the deleterious effects of radiation on mediastinal structures. More studies are needed to identify the optimal way of managing patients with radiation-induced AS, and algorithms are needed for planning these complex interventions.

Lifetime Management of Aortic Stenosis: Transcatheter Versus Surgical Treatment for Young and Low-Risk Patients

Transcatheter aortic valve replacement is now indicated across all risk categories of patients with symptomatic severe aortic stenosis and has been proposed as first line option for the majority of patients >74 years old. However, median age of patients enrolled in the transcatheter aortic valve replacement low-risk trials is 74 years and transcatheter aortic valve replacement has never been systematically investigated in young low risk patients. Although the long-term data in surgical aortic valve replacement in young patients (age <75) are well known, such data remain lacking in transcatheter aortic valve replacement. In the absence of clear guideline recommendations in patients with challenging anatomies (eg, hostile calcium, bicuspid), it is important to know the potential advantages and disadvantages of each treatment and to consider how they might integrate with each other in the lifetime management of such patients. In this review, we discuss current outstanding issues on the management of severe aortic stenosis from a lifetime management perspective, particularly in terms of initial intervention and future reinterventions.

Incidence, causes, correlates, and outcome of bioprosthetic valve dysfunction and failure following transcatheter aortic valve implantation

AIMS

Bioprosthetic valve dysfunction (BVD) is a major concern regarding transcatheter aortic valve implantation (TAVI) durability. We aimed to assess incidence, correlates, causes, and outcome of early to mid-term BVD after TAVI in relation to patient's life expectancy.

METHODS AND RESULTS

Consecutive TAVI recipients (2007-20) with a follow-up ≥1 year were prospectively included. BVD and bioprosthetic valve failure (BVF) were assessed according to Valve-Academic-Research-Consortium-3. BVD/BVF and all-cause death served as endpoints. Average life expectancy was calculated from National Open Health Data and patients were stratified according to tertiles (1st: <6.85 years, 2nd: 6.85-9.7 years, 3rd: >9.7 years). Of 1047 patients (81.6 ± 6.8 years old, EuroSCORE II 4.5 ± 2.5), ≥2 follow ups were available from 622 (serial echo cohort). After a median echo follow up of 12.2 months, incidence rates of BVD/BVF were 8.4% (95% confidence interval 6.7-10.3), and 3.5% (2.5-4.9) per valve-year, respectively, without differences between life expectancy tertiles. The incidence of BVD was two-fold higher within the first year of implant (9.9% per valve-year) vs. beyond (4.8% per valve-year). Valve-in-valve procedure and residual stenosis, but not age/life expectancy predisposed for BVD. BVD/BVF were independently associated with outcome for patients in the first [adjusted hazard ratio (AHR) 1.72 (1.06-2.88)/2.97 (1.72-6.22)] and second [AHR 1.96 (1.02-3.73)/2.31 (1.00-5.30)], but not the third tertile of life expectancy (P = n.s.).

CONCLUSIONS

In this large prospective observational cohort, early to mid-term BVD after TAVI occurred at the same rate across the spectrum of life expectancy and was associated with increased mortality in patients with short but not in those with the longest life expectancy.

A biomimetic multilayered polymeric material designed for heart valve repair and replacement

Materials currently used to repair or replace a heart valve are not durable. Their limited durability related to structural degeneration or thrombus formation is attributed to their inadequate mechanical properties and biocompatibility profiles. Our hypothesis is that a biostable material that mimics the structure, mechanical and biological properties of native tissue will improve the durability of these leaflets substitutes and in fine improve the patient outcome. Here, we report the development, optimization, and testing of a biomimetic, multilayered material (BMM), designed to replicate the native valve leaflets. Polycarbonate urethane and polycaprolactone have been processed as film, foam, and aligned fibers to replicate the leaflet's architecture and anisotropy, through solution casting, lyophilization, and electrospinning. Compared to the commercialized materials, our BMMs exhibited an anisotropic behavior and a closer mechanical performance to the aortic leaflets. The material exhibited superior biostability in an accelerated oxidization environment. It also displayed better resistance to protein adsorption and calcification in vitro and in vivo. These results will pave the way for a new class of advanced synthetic material with long-term durability for surgical valve repair or replacement.

Surgical Management of Complex Aortic Valve Disease in Young Adults: Repair, Replacement, and Future Alternatives

The ideal aortic valve substitute in young adults remains unknown. Prosthetic valves are associated with a suboptimal survival and carry a significant risk of valve-related complications in young patients, mainly reinterventions with tissue valves and, thromboembolic events and major bleeding with mechanical prostheses. The Ross procedure is the only substitute that restores a survival curve similar to that of a matched general population, and permits a normal life without functional limitations. Though the risk of reintervention is the Achilles' heel of this procedure, it is very low in patients with aortic stenosis and can be mitigated in patients with aortic regurgitation by tailored surgical techniques. Finally, the Ozaki procedure and the transcatheter aortic valve implantation are seen by many as future alternatives but lack evidence and long-term follow-up in this specific patient population.

Transcatheter aortic valve replacement for structural degeneration of previously implanted transcatheter valves (TAVR-in-TAVR): a systematic review

OBJECTIVES

Transcatheter aortic valve replacement (TAVR) represents a valid treatment for patients with aortic valve stenosis and high or intermediate surgical risk. However, biological transcatheter valves can also experience a structural degeneration after years, and a redo-TAVR procedure (TAVR-in-TAVR) can be a valid option. We revised the current available literature for indications, procedural and technical details and outcome on TAVR-in-TAVR procedures for degenerated TAVR valves.

METHODS

A systematic search was conducted in the public medical database for scientific articles on TAVR-in-TAVR procedures for degenerated transcatheter valves. Data on demographics, indications, first and second transcatheter valve type and size, mortality, complications and follow-up were extracted and analysed.

RESULTS

A total of 13 studies (1 multicentre, 3 case series, 9 case reports) were included in this review, with a total amount of 160 patients treated with TAVR-in-TAVR procedures for transcatheter valve failure. The mean age was 74.8 ± 7.8 with 84 males (52.8%). The mean elapsed time from the first TAVR procedure was 58.1 ± 23.4 months. Main indication for TAVR-in-TAVR was pure stenosis (38.4%, with mean gradient of 44.5 ± 18.5 mmHg), regurgitation (31.4%), mixed stenosis and regurgitation (29.5%) and leaflet thrombosis (8.8%). Procedural success rate was 86.8%, with second TAVR valve malposition occurred in 4 cases (2.5%). The hospital mortality rate was 1.25% (2/160). Post-procedural echocardiographic control showed moderate regurgitation in 5.6% of patients (9/160) and residual transvalvular mean gradient ≥20 mmHg in 5% of cases. Postoperative complications included major vascular complications (8.7%), new pacemaker implantation (8.7%), acute kidney failure (3.7%), stroke (0.6%) and coronary obstruction (0.6%). The mean follow-up time was 6 ± 5.6 months with 1 non-cardiovascular death reported.

CONCLUSIONS

TAVR-in-TAVR represents a valid alternative to standard surgery for the treatment of degenerated transcatheter valves in high-risk patients. Despite these promising results, further studies are required to assess durability and haemodynamic performances of the second TAVR valve.

SUBJ COLLECTION

117, 122, 125.

Treatment of Bicuspid Aortic Valve Stenosis Using Transcatheter Heart Valves

The paucity of data regarding the use of transcatheter aortic valve replacement (TAVR) in bicuspid aortic valve (BAV) anatomy due to exclusion from pivotal studies and lack of studies assessing the long-term outcomes and valve performance continue to present a significant challenge as we expand TAVR to patients with BAV anatomy. This article discusses the important anatomic and clinical considerations in the selection and management of patients with BAV with TAVR and reviews the emerging evidence that increasingly suggests this procedure is safe, device success is excellent, and procedural outcomes are improving.

Aortic valve replacement in patients over 60: Real-world surgical outcomes

OBJECTIVE

With the advent of transcatheter aortic valve implantation (TAVI) has come an expectation that there will be a decline in surgical aortic valve replacement (SAVR). This has been fueled by trials comparing outcomes between TAVI and SAVR in lower-risk patients. The aim of this study was to examine outcomes following SAVR in patients over the age of 60.

MATERIALS AND METHODS

This retrospective cohort study observed 1005 patients ≥60 who underwent isolated primary SAVR from January 2015 to December 2018. The cohort was stratified by surgical risk, defined as European System for Cardiac Operative Risk Evaluation (EuroSCORE) II < 4 versus ≥4. The cohort was also divided by age (60-69, 70-79, ≥80) for additional comparisons. Outcomes included in-hospital complications and patient survival.

RESULTS

The median age and EuroSCORE II were 75 years and 1.6, respectively. The overall 30-day mortality was 1.7% and increased significantly with surgical risk (p = .007). The 30-day mortality of elective patients was 1.1%. Overall, 1- and 2-year survival rates were 94.3% and 91.7%, respectively, which significantly decreased with surgical risk (p < .001) and age (p = .002, p = .003). The rates of postoperative stroke and pacemaker implantations were 1.2% and 3.6%, respectively.

CONCLUSIONS

SAVR can be performed in patients ≥60 years old with excellent outcomes, which compare favorably with outcomes from TAVI trials, with their highly selected patient cohorts. SAVR remains a reliable, tried and tested, treatment option in these patients.

Decision analysis and personalized clinical tool for cerebrospinal fluid drains in thoracoabdominal aortic aneurysms repair

BACKGROUND AND AIM

The routine use of cerebrospinal fluid (CSF) drainage in patients undergoing operative repair of thoracoabdominal aneurysms (TAAA) has been associated with decreased rates of spinal cord ischemia. The use of CSF drains is not without consequence, however with complications including subarachnoid hemorrhage, epidural hematoma, meningitis, and, in 1% of cases, death. To date, a decision analysis tool to help clinicians decide when to use and not to use a CSF drain does not exist. In this analysis, we set out to develop a decision analysis tool for CSF drain placement in patients undergoing operative repair of TAAA.

METHODS

A Markov state-transition cohort model that compared TAAA repair with adjunctive CSF drain insertion to TAAA repair without drain insertion for the outcome of life expectancy was developed in TreeAge 2020. The cycle length was 1 month and the time horizon was 60 months.

RESULTS

The use of a CSF drain was associated with improved 5-year life expectancy (3.21 ± 0.10 vs. 3.09 ± 0.11 life-years gained). In the sensitivity analysis that varied the effectiveness of a CSF drain (odds ratio closer to 1 = less effective), the use of a CSF drain resulted in higher life expectancy in almost all scenarios.

CONCLUSIONS

The routine use of a CSF drain in patients undergoing TAAA repair is safe and effective, with few exceptions. This decision analysis tool can be used by clinicians to develop a personalized approach.