Current issues in transcatheter aortic valve replacement

Calcific aortic valve disease: mechanisms, prevention and treatment

Calcific aortic valve disease (CAVD) is the most common disorder affecting heart valves and is characterized by thickening, fibrosis and mineralization of the aortic valve leaflets. Analyses of surgically explanted aortic valve leaflets have shown that dystrophic mineralization and osteogenic transition of valve interstitial cells co-occur with neovascularization, microhaemorrhage and abnormal production of extracellular matrix. Age and congenital bicuspid aortic valve morphology are important and unalterable risk factors for CAVD, whereas additional risk is conferred by elevated blood pressure and plasma lipoprotein(a) levels and the presence of obesity and diabetes mellitus, which are modifiable factors. Genetic and molecular studies have identified that the NOTCH, WNT-β-catenin and myocardin signalling pathways are involved in the control and commitment of valvular cells to a fibrocalcific lineage. Complex interactions between valve endothelial and interstitial cells and immune cells promote the remodelling of aortic valve leaflets and the development of CAVD. Although no medical therapy is effective for reducing or preventing the progression of CAVD, studies have started to identify actionable targets.

A 20-year journey in transcatheter aortic valve implantation: Evolution to current eminence

Since the first groundbreaking procedure in 2002, transcatheter aortic valve implantation (TAVI) has revolutionized the management of aortic stenosis (AS). Through striking developments in pertinent equipment and techniques, TAVI has now become the leading therapeutic strategy for aortic valve replacement in patients with severe symptomatic AS. The procedure streamlining from routine use of conscious sedation to a single arterial access approach, the newly adapted implantation techniques, and the introduction of novel technologies such as intravascular lithotripsy and the refinement of valve-bioprosthesis devices along with the accumulating experience have resulted in a dramatic reduction of complications and have improved associated outcomes that are now considered comparable or even superior to surgical aortic valve replacement (SAVR). These advances have opened the road to the use of TAVI in younger and lower-risk patients and up-to-date data from landmark studies have now established the outstanding efficacy and safety of TAVI in patients with low-surgical risk impelling the most recent ESC guidelines to propose TAVI, as the main therapeutic strategy for patients with AS aged 75 years or older. In this article, we aim to summarize the most recent advances and the current clinical aspects involving the use of TAVI, and we also attempt to highlight impending concerns that need to be further addressed.

Costs and outcomes of mobile cardiac outpatient telemetry monitoring post-transcatheter aortic valve replacement

Aim: To estimate the costs and outcomes of transcatheter aortic valve replacement (TAVR) recipients based on the use of mobile cardiac outpatient telemetry (MCOT) monitoring. Materials & methods: A retrospective database study was conducted to estimate costs, contribution margins (CMs), pacemaker insertions, and other outcomes for patients undergoing TAVR procedures with MCOT monitoring post-procedure versus non-MCOT monitoring. Results: A total of 4164 patients were identified (283 MCOT monitoring and 3881 non-MCOT monitoring). The rate of pacemaker insertion following hospital discharge was higher in the MCOT cohort (6.6 MCOT vs 2.1% non-MCOT; p = 0.007). MCOT use was associated with lower costs and improved CMs of the index TAVR admission (costs: US$40,569 MCOT vs $43,289 non-MCOT; p = 0.003; CMs: US$7087 MCOT vs $5177 non-MCOT; p = 0.047) with no difference through the subsequent 60-day period following discharge. Conclusion: MCOT for ambulatory cardiac monitoring post-TAVR discharge is associated with higher rates of pacemaker insertion, at no overall greater costs.

Surgical explantation of failed transcatheter heart valves: indications and results

Given the recent surge in transcatheter heart valve replacement (THVR), cardiac surgeons will surely face the challenge of eventual explantation. The aim of this study was to determine indications for reoperation, while exploring pertinent technical aspects and survival after THV explantation in a cohort originally deemed high risk or even inoperable. Between February 2008 and March 2019, 31 patients with failed transcatheter aortic valve replacement (TAVR) underwent surgical explantations at our facility. Data were prospectively collected for retrospective analysis of procedural indications, technical issues, and postoperative survival. The major reason for TAVR removal was bioprosthetic valve failure (BVF) due to infective endocarditis (IE: 16/31 [51.6%]), non-structural (NSVD: 14/31 [45.2%]) and structural (SVD: 1/31 [3.2%]) valve deterioration accounting for the rest. Mean age at THV explantation was 76.3 ± 8.3 years, and median time from TAVR to explantation was 153 days (0 days-56.6 months). Median ICU and hospital stay were 6 days (1-44 days) and 23 days (8-62 days), respectively. Thirty-day and 1-year survival rates were 74.2% and 67.2%, respectively. Median follow-up interval after explantation was 364 days (3 days-80 months). Mean cardiopulmonary bypass time was 124.6 ± 46.8 min, and mean aortic cross-clamp time was 84.3 ± 32.9 min. There was no need for unplanned aortic root repair owing to tissue damage during dissection of the TAVR from surrounding tissue. The most common reason for THV explantation was (a) BVF for IE and (b) BVF secondary to NSVD. Although 30-day and 1-year mortality rates in this multimorbid cohort were predictably high, no procedural mortalities occurred.

On the Modeling of Transcatheter Therapies for the Aortic and Mitral Valves: A Review

Transcatheter aortic valve replacement (TAVR) has become a milestone for the management of aortic stenosis in a growing number of patients who are unfavorable candidates for surgery. With the new generation of transcatheter heart valves (THV), the feasibility of transcatheter mitral valve replacement (TMVR) for degenerated mitral bioprostheses and failed annuloplasty rings has been demonstrated. In this setting, computational simulations are modernizing the preoperative planning of transcatheter heart valve interventions by predicting the outcome of the bioprosthesis interaction with the human host in a patient-specific fashion. However, computational modeling needs to carry out increasingly challenging levels including the verification and validation to obtain accurate and realistic predictions. This review aims to provide an overall assessment of the recent advances in computational modeling for TAVR and TMVR as well as gaps in the knowledge limiting model credibility and reliability.

Low Circulating Musclin is Associated With Adverse Prognosis in Patients Undergoing Transcatheter Aortic Valve Implantation at Low-Intermediate Risk

Background

Musclin is an activity‐stimulated and cardioprotective myokine that attenuates pathological cardiac remodeling. Musclin deficiency, in turn, results in reduced physical endurance. The aim of this study was to assess the prognostic value of circulating musclin as a novel, putative biomarker to identify patients undergoing transcatheter aortic valve implantation (TAVI) who are at a higher risk of death.

Methods and Results

In this study, we measured systemic musclin levels in 368 patients undergoing TAVI who were at low to intermediate clinical risk (median EuroSCORE [European System for Cardiac Operative Risk Evaluation] II: 3.5; quartile 1–quartile, 2.2%–5.3%), whereby 209 (56.8%) patients were at low and 159 (43.2%) were at intermediate risk. Median preprocedural musclin levels were 2.7 ng/mL (quartile 1–quartile 3, 1.5–4.6 ng/mL). Musclin levels were dichotomized in low (<2.862 ng/mL, n=199 [54.1%]) or high (≥ 2.862 ng/mL, n=169 [45.9%]) groups using cutoff values determined by classification and regression tree analysis. The primary end point was 1‐year overall survival. Patients with low circulating musclin levels exhibited a significantly higher prevalence of frailty, low albumin values, hypertension, and history of stroke as well as higher N‐terminal pro‐B‐type natriuretic peptide. Low musclin levels significantly predicted risk of death in univariable (hazard ratio, 1.81; 95% CI, 1.00–3.53 [P=0.049]) and multivariable (adjusted hazard ratio, 2.45; 95% CI, 1.06–5.69 [P=0.037]) Cox regression analyses. Additionally, low musclin levels in combination with conventional EuroSCORE II suggested improved risk stratification in patients undergoing TAVI who were at low to intermediate clinical risk into subgroups with reduced 1‐year survival rates by log‐rank test (P for trend=0.003).

Conclusions

Circulating musclin is an independent predictor of 1‐year overall survival in patients undergoing TAVI. Combined with EuroSCORE II, circulating musclin might help to improve prediction of mortality in patients undergoing TAVI who are at low to intermediate clinical risk.

Personalized Preoperative Prediction of the Length of Hospital Stay after TAVI Using a Dedicated Decision Tree Algorithm

Background: The aim of this study was to identify pre-operative parameters able to predict length of stay (LoS) based on clinical data and patient-reported outcome measures (PROMs) from a scorecard database in patients with significant aortic stenosis who underwent TAVI (transfemoral aortic valve implantation). Methods: 302 participants (51.7% males, age range 78.2−84.2 years.) were prospectively recruited. After computing the median LoS value (=6 days, range = 5−8 days), we implemented a decision tree algorithm by setting dichotomized values at median LoS as the dependent variable and assessed baseline clinical variables and PROMs (Clinical Frailty Scale (CFS), EuroQol-5 Dimension-5 Levels (EQ-5D) and Kansas City Cardiomyopathy Questionnaire (KCCQ)) as potential predictors. Results: Among clinical parameters, only peripheral arterial disease (p = 0.029, HR = 1.826) and glomerular filtration rate (GFR, cut-off < 33 mL/min/1.73 m2, p = 0.003, HR = 2.252) were predictive of LoS. Additionally, two PROMs (CFS; cut-off = 3, p < 0.001, HR = 1.324 and KCCQ; cut-off = 30, p = 0.003, HR = 2.274) were strong predictors. Further, a risk score for LoS (RS_LoS) was calculated based on these predictors. Patients with RS_LoS = 0 had a median LoS of 5 days; patients RS_LoS ≥ 3 had a median LoS of 8 days. Conclusions: based on the pre-operative values of the above four predictors, a personalized prediction of LoS after TAVI can be achieved.

Assessment of Paravalvular Leak Severity and Thrombogenic Potential in Transcatheter Bicuspid Aortic Valve Replacements Using Patient-Specific Computational Modeling

Bicuspid aortic valve (BAV), the most common congenital valvular abnormality, generates asymmetric flow patterns and increased stresses on the leaflets that expedite valvular calcification and structural degeneration. Recently adapted for use in BAV patients, TAVR demonstrates promising performance, but post-TAVR complications tend to get exacerbated due to BAV anatomical complexities. Utilizing patient-specific computational modeling, we address some of these complications. The degree and location of post-TAVR PVL was assessed, and the risk of flow-induced thrombogenicity was analyzed in 3 BAV patients - using older generation TAVR devices that were implanted in these patients, and compared them to the performance of the newest generation TAVR devices using in silico patient models. Significant decrease in PVL and thrombogenic potential was observed after implantation of the newest generation device. The current work demonstrates the potential of using simulations in pre-procedural planning to assess post-TAVR complications, and compare the performance of different devices to achieve better clinical outcomes. Patient-specific computational framework to assess post-transcatheter bicuspid aortic valve replacement paravalvular leakage and flow-induced thrombogenic complications and compare device performances.

In silico approaches for transcatheter aortic valve replacement inspection

Introduction: Increasing applications of transcatheter aortic valve replacement (TAVR) to treat high- or medium-risk patients with aortic diseases have been proposed in recent years. Despite its increasing use, many influential factors are still to be understood. Furthermore, innovative applications of TAVR such as in bicuspid aortic valves or in low-risk patients are emerging in clinical use. Numerical analyses are increasingly used to reproduce clinical treatments. The future trends in this area are foreseen for in silico trials and personalized medicine. Areas covered: This review paper analyzes the recent years (Jan 2018 - Aug 2020) of in silico studies simulating the behavior of transcatheter aortic valves with emphasis on the addressed clinical question and the used modeling strategies. The manuscripts are firstly classified based on their clinical hypothesis. A second classification is based on the adopted modeling approach in terms of patient domain, device modeling, and inclusion or exclusion of the fluid domain. Expert opinion: The TAVR can be virtually performed in numerous vessel geometries and with different devices. This versatility allows a rapid evaluation of the feasibility of different implantation approaches for specific patients, and patient populations, resulting in faster and safer introduction or optimization of new treatments or devices.

TAVR: A Review of Current Practices and Considerations in Low-Risk Patients

Transcatheter aortic valve replacement (TAVR) is an established treatment for severe, symptomatic, aortic stenosis (AS) in patients of all risk categories and now comprises 12.5% of all aortic valve replacements. TAVR is a less invasive alternative to traditional surgical aortic valve replacement (SAVR), with equivalent or superior outcomes. The use of TAVR has increased rapidly. The success and increase in use of TAVR are a result of advances in technology, greater operator experience, and improved outcomes. Indications have recently expanded to include patients considered to be at low risk for SAVR. While TAVR outcomes have improved, remaining challenges include the management of coexistent coronary artery disease, prevention of periprocedural stroke, and issue of durability. These issues are even more relevant for low-risk, younger patients.

Potential Role and Prognostic Value of Erythropoietin Levels in Patients With Severe Aortic Stenosis Undergoing Transcatheter Aortic Valve Replacement

Background: Both EPO levels and anemia have shown prognostic value in several cardiac disorders. An observational study with a prospective follow-up was performed to investigate their independent prognostic roles in severe aortic stenosis.

Methods: An up to 36-month follow-up of consecutive patients with severe aortic stenosis undergoing TAVR in a high-volume center was performed. Patients with eGRF <30 mL/min/1.73 m² were excluded. EPO levels and/or anemia status and its association with mid-term mortality were assessed.

Results: Out of 407, 360 met eligibility criteria. Median age was 83 years, with 71.4% having a NYHA class III/IV. Anemia was present in 51.9%, and iron deficiency in 52.8%. Median (IQR) EPO levels were 14.4 (9.30–24.30) mIU/mL. Median follow-up was 566 days. Anemia was associated with overall mortality (HR 2.40, 95% CI 1.51–3.80, p < 0.001). Higher logEPO levels were associated with mid-term mortality (HR 4.05, 95% CI 2.29–7.16, p < 0.001), even after adjusting for clinically and/or statistically relevant factors (multivariate HR 2.25, 95 CI 1.09–4.66, p = 0.029). Kaplan-Meier analyses showed early diverging curves for anemia vs. non-anemia, whereas curves for patients in various EPO level quartiles started to diverge at about 100 days, with differences consistently increasing during the subsequent entire follow-up period.

Conclusions: Differently from anemia, which was a strong predictor for both early and late mortality in severe aortic stenosis after TAVR, independent prognostic value of EPO only emerged after post-TAVR recovery. EPO prognostic value was independent from anemia and mild-to-moderate renal dysfunction. High EPO levels could be useful to identify patients with severe aortic stenosis showing a compromised mid-term survival in spite of TAVR use and independently from early TAVR results.