Prognosis after surgical replacement with a bioprosthetic aortic valve in patients with severe symptomatic aortic stenosis: systematic review of observational studies

A Review of the Partner Trials

Aortic stenosis (AS) of moderate or greater severity has an estimated prevalence of 5% in people older than 65 years. Survival is poor after onset of symptoms, and surgical aortic valve replacement was the gold-standard treatment for decades. However, more than one-third of patients with symptomatic AS were untreated due to high surgical risk, exposing a clinical need for a less invasive therapy for aortic valve stenosis. The PARTNER trials were pivotal in presenting robust evidence for the safety, feasibility, and efficacy of transcatheter aortic valve replacement in the management of AS and paved the way for clinical use worldwide.

Surgical vs transfemoral aortic valve replacement in low-risk patients: An updated meta-analysis of trial and registry data

BACKGROUND

Transfemoral aortic valve replacement (TAVR) has been studied extensively in patients with improving safety and efficacy in high to intermediate-risk patients with aortic stenosis. TAVR has been now approved for patients with low surgical risk.

OBJECTIVE

The purpose of this study is to integrate the evidence from randomized controlled trials (RCT) and large registry data comparing TAVR to surgical aortic valve repair (SAVR).

METHODS

Seven studies (three RCTs, one post hoc study of a RCT, and three registries) were included. Incidence rate ratios (IRR) of outcomes of interest (overall mortality, 30-day mortality, cardiovascular death, stroke, pacemaker implantation [PPMI], myocardial infarction, moderate-severe paravalvular leak [PVL], and re-intervention) were compared using a random-effects model.

RESULTS

The pooled analysis included 24 819 patients (TAVR, 8227 and SAVR, 16 592). 2,952 (11.9%) patients were from RCTs and 21 867 (88.1%) were registry patients. Thirty-day mortality was lower in TAVR (logIRR, -0.43; 95% CI. -0.61 to -0.25; P < .001), whereas the rate of moderate-severe PVL (logIRR, 1.44; 95% CI, 0.58-2.3; P < .001) and PPMI (logIRR, 1.13; 95% CI, 1.02-1.24; P < .001) were higher. There were no significant differences in the rates of overall mortality, reintervention, cardiovascular death, myocardial infarction, or stroke between SAVR and TAVR.

CONCLUSIONS

Early mortality is higher in SAVR while rates of PVL and PPMI are substantially higher in TAVR. There is no significant advantage with TAVR for overall survival, cardiovascular death, stroke, MI, and re-intervention rates.

Risk Factors of Multidrug-Resistant Bacteria in Lower Respiratory Tract Infections: A Systematic Review and Meta-Analysis

Background

Multidrug-resistant (MDR) bacteria are the main cause of lower respiratory tract infections (LRTIs) with high mortality. The purpose of this study is to identify the risk factors associated with MDR by performing a systematic review and meta-analysis.

Methods

PubMed, EMBASE (via Ovid), and Cochrane Library were systematically searched for studies on the risk factors for MDR bacteria in LRTIs as of November 30, 2019. Literature screening, data abstraction, and quality assessment of the eligible studies were performed independently by two researchers.

Results

A total of 3,607 articles were retrieved, of which 21 articles representing 20 cohort studies published in English were included after title/abstract and full-text screening. Among the 21 articles involving 7,650 patients and 1,360 MDR organisms, ten reported the risk factors for MDR Gram-positive bacteria (GPB) and Gram-negative bacteria (GNB), ten for MDR GNB, and one for MDR GPB. The meta-analysis results suggested that prior antibiotic treatment, inappropriate antibiotic therapy, chronic lung disease, chronic liver disease and cerebral disease, prior MDR and PA infection/colonization, recent hospitalization, longer hospitalization stay, endotracheal tracheostomy and mechanical ventilation, tube feeding, nursing home residence, and higher disease severity score were independent risk factors for MDR bacteria.

Conclusions

This review identified fourteen clinical factors that might increase the risk of MDR bacteria in patients with LRTIs. Clinicians could take into account these factors when selecting antibiotics for patients and determine whether coverage for MDR bacteria is required. More well-designed studies are needed to confirm the various risk factors for MDR bacteria in the future.

Life expectancy of patients undergoing surgical aortic valve replacement compared with that of the general population

OBJECTIVES

Surgical aortic valve replacement (SAVR) changes the natural history of severe aortic stenosis. However, whether the life expectancy of patients with severe aortic stenosis undergoing this surgical procedure is fully restored is unknown. The objective of this study was to assess if the life expectancy of patients aged >75 years is fully restored after undergoing surgery for severe aortic stenosis.

METHODS

We compared long-term survival of a group of patients aged >75 years, who underwent SAVR at our institution with the long-term survival of the general population. We matched each patient with 100 simulated individuals (control group) of the same age, sex and geographical region who died as indicated by the National Institute of Statistics. We compared survival curves and calculated hazard ratio (HR) or incidence rate ratio. Statistical significance existed if confidence intervals (CIs) did not overlap or did not include the value 1, as appropriate.

RESULTS

Average life expectancy of surgical patients who survived the postoperative period was 90.91 months (95% CI 82.99-97.22), compared to 92.94 months (95% CI 92.39-93.55) in the control group. One-, 5- and 8-year survival rates for SAVR patients who were discharged from the hospital were 94.9% (95% CI 92.74-96.43%), 71.66% (95% CI 67.37-75.5%) and 44.48% (95% CI 38.14-50.61%), respectively, compared to that of the general population: 95.8% (95% CI 95.64-95.95%), 70.64% (95% CI 70.28%-71%) and 47.91% (95% CI 47.52-48.31%), respectively (HR 1.07, 95% CI 0.94-1.22).

CONCLUSION

For patients over the age of 75 years who underwent SAVR and survived the postoperative period, life expectancy and survival rates were similar to that of the general population.

Meta-Analysis of Transcatheter Aortic Valve Implantation Versus Surgical Aortic Valve Replacement in Patients With Low Surgical Risk

Transcatheter aortic valve implantation (TAVI) is the current standard of care for patients with severe aortic stenosis who are at high risk for surgery. However, several recent studies have demonstrated the comparable safety and efficacy of TAVI in low-risk patients as well. We sought to pool the existing data to further assert its comparability. MEDLINE, Cochrane, and Embase databases were evaluated for relevant articles published from January 2005 to June 2019. Studies comparing outcomes of TAVI versus surgical aortic valve replacement in patients who are at low risk for surgery were included. Twelve studies (5 randomized controlled trials and 7 observational studies) totaling 27,956 patients were included. Follow-up ranged from 3 months to 5 years. Short-term all-cause mortality, short-term, and 1-year cardiac mortality were significantly lower in the TAVI group. One-year all-cause mortality, short-term, and 1-year stroke and myocardial infarction were similar in both groups. Rate of acute kidney injury and new-onset atrial fibrillation were lower in the TAVI group, whereas permanent pacemaker implantation and major vascular complications were higher in the TAVI group. Subgroup analysis of randomized controlled trials showed significantly lower 1-year all-cause mortality in the TAVI group. In conclusion, in severe aortic stenosis patients at low surgical risk, TAVI when compared with surgical aortic valve replacement, demonstrated a lower rate of short-term all-cause mortality, short-term, and 1-year cardiac mortality and similar in terms of 1-year all-cause mortality. TAVI is emerging as a safe and efficacious alternative for low surgical risk patients.

Postimplant biological aortic prosthesis degeneration: challenges in transcatheter valve implants

Surgical aortic valve replacement (SAVR) is highly effective and can be achieved with relatively low risk in patients with severe aortic stenosis. Bioprostheses have been used most frequently during the past 60 years. However, the function of biological valves usually declines after 10-15 years from implant when structural valve degeneration occurs often mandating a reoperation once valve dysfunction becomes haemodynamically significant. Known for many years by surgeons and cardiologists taking care of patients with SAVR, the issue of postimplant structural valve degeneration has been recently highlighted also in patients with transcatheter aortic valve implant (TAVI). There is growing concern that TAVI valves exhibit structural valve degeneration due to inherent challenges of the deployment mode. The impact on postimplant degeneration of TAVI valves compared to SAVR has still to be understood and defined. Based on the ongoing process of expanding TAVI indications, several potential shortcomings and caveats, learned during the last 60 years of SAVR experience, should be taken into consideration to refine this technique.

Aortic Stenosis: Guidelines and Evidence Gaps

Current guidelines for management of adults with aortic stenosis recommend aortic valve replacement for patients with clinical consequences due to hemodynamically severe valve obstruction. However, advances in surgical and transcatheter techniques, and improved valve design have led to decreased procedural risk and improved long-term outcomes. Transcatheter aortic valve replacement (TAVR) is recommended for patients with prohibitive surgical risk and is reasonable in intermediate and high-risk patients. Recent trials demonstrated favorable short-term outcomes in patients with low surgical risk undergoing TAVR compared with surgical AVR. We review the current Guidelines recommendations and highlight key controversies in management due to evidence gaps.

Bioprosthetic Heart Valve Degeneration and Dysfunction: Focus on Mechanisms and Multidisciplinary Imaging Considerations

Bioprosthetic heart valves (BPHVs) have fundamentally changed the treatment of valvular heart disease. Despite the continuous progress of BPHVs, from early valve designs for use in surgical replacement to the rapidly evolving use of transcatheter replacement techniques and designs, valve dysfunction and degeneration remain fundamental issues. Current guidelines and proposed standard definitions of BPHV dysfunction and degeneration outline the importance of imaging. Imaging plays a key role in understanding valve degeneration, including clinical imaging to identify transvalvular gradients, leaflet thickening, thrombosis, calcification, and restricted or reduced leaflet motion. Similarly, translational imaging approaches-including micro-CT, high-speed video, computational modeling, and high-resolution microscopy-and histologic analysis are crucial to understanding mechanisms of valve degeneration and factors that may contribute to valve dysfunction. This article provides an overview of valve dysfunction and degeneration and the role of imaging. © RSNA, 2019.

In vitro hemodynamic assessment of a novel polymeric transcatheter aortic valve

Transcatheter aortic valve replacement (TAVR) is a life-saving alternative to surgical intervention. However, the identification of features associated with poor outcomes, including residual paravalvular leakage (PVL), leaflet calcification, and subclinical leaflet thrombosis, are cause to be concerned about valve durablilty (Mylotte and Piazza, 2015a, 2015b; Dasi et al., 2017; Makkar et al., 2015; Kheradvar et al., 2015a). The aim of this study is to optimize the potential of a hyaluronan (HA) enhanced polymeric transcatheter aortic valve (HA-TAV) that has promised to reduce blood damage causing-turbulent flow while maintaining durability. HA-enhanced linear low-density polyethylene (LLDPE) leaflets were sutured to novel cobalt chromium stents, size 26 mm balloon expandable stents. Hemodynamic performance was assessed in a left heart simulator under physiological pressure and flow conditions and compared to a 26 mm Medtronic Evolut and 26 mm Edwards SAPIEN 3. High-speed imaging and particle image velocimetry (PIV) were performed. The HA-TAV demonstrated an effective orifice area (EOA) within one standard deviation of the leading valve, SAPIEN 3.The regurgitant fraction (RF) of the HA-TAV (11.23 ± 0.55%) is decreased in comparison the Evolut (15.74 ± 0.73%) and slightly higher than the SAPIEN 3 (10.92 ± 0.11%), which is considered trace regurgitation according to valve standards. A decreased number of higher principal Reynolds shear stresses were shown for the HA-TAV at each cardiac phase. The HA-TAV is directly comparable and in some cases superior to the leading commercially available prosthetic heart valves in in-vitro hemodynamic testing.

Estimating the additional costs per life saved due to transcatheter aortic valve replacement: a secondary data analysis of electronic health records in Germany

Aortic stenosis (AS) is the most common valvular heart disease, with a dismal prognosis when untreated. Recommended therapy is surgical (SAVR) or transcatheter (TAVR) aortic valve replacement. Based on a retrospective cohort of isolated SAVR and TAVR procedures performed in Germany in 2015 (N = 17,826), we examine the impact of treatment selection on in-hospital mortality and total in-hospital costs for a variety of at-risk populations. Since patients were not randomized to the two treatment options, the two endpoints in-hospital mortality and reimbursement are analyzed using logistic and linear regression models with 20 predefined patient characteristics as potential confounders. Incremental cost-effectiveness ratios were calculated as a ratio of the risk-adjusted reimbursement and mortality differences with 95% confidence intervals obtained by Fieller's theorem. Our study shows that TF-TAVR is more costly that SAVR and that cost differences between the procedures vary little between patient groups. Results regarding in-hospital mortality are mixed. SAVR is the predominant procedure among younger patients. For patients older than 85 years or at intermediate and higher pre-operative risk TF-TAVR seems to be the treatment of choice. Incremental cost-effectiveness ratios (ICER) are most favorable for patients older than 85 years (ICER €154,839, 95% CI €89,163-€302,862), followed by patients at higher pre-operative risk (ICER €413,745, 95% CI €258,027-€952,273). A hypothetical shift from SAVR towards TF-TAVR among patients at intermediate pre-operative risk is associated with a less favorable ICER (€1,486,118, 95% CI €764,732-€23,692,323), as the risk-adjusted mortality benefit is relatively small (- 0.97% point), while the additional reimbursement is still eminent (+€14,464). From a German healthcare system payer's perspective, the additional costs per life saved due to TAVR are most favorable for patients older than 85 and/or at higher pre-operative risk.

Prognostic Value of Sarcopenia in Lung Cancer: A Systematic Review and Meta-analysis

BACKGROUND

Evidence regarding the association between sarcopenia (skeletal muscle depletion) and outcomes in patients with lung cancer varies across studies. We aimed to systematically review the prognostic value of sarcopenia in lung cancer.

METHODS

We searched Ovid MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials through July 23, 2018 to identify retrospective or prospective cohort studies. We applied the Quality in Prognostic Studies instrument to assess the risk of bias in individual studies. We examined the heterogeneity and publication bias and performed subgroup analyses and sensitivity analyses.

RESULTS

We included 13 studies (1,810 participants). The pooled prevalence of sarcopenia was 43% in patients with non-small cell lung cancer (NSCLC) and 52% in patients with small cell lung cancer (SCLC). Sarcopenia was associated with a shorter overall survival (OS) in patients with lung cancer (hazard ratio [HR], 2.23; 95% CI, 1.68-2.94). This association existed for both NSCLC (HR, 2.57; 95% CI, 1.79-3.68) and SCLC (HR, 1.59; 95% CI, 1.17-2.14). Sarcopenia was an independent predictor of shorter OS in both stage I-II NSCLC (HR, 3.23; 95% CI, 1.68-6.23) and stage III-IV NSCLC (HR, 2.19; 95% CI, 1.14-4.24). However, sarcopenia was not an independent predictor of disease-free survival in patients with NSCLC (HR, 1.28; 95% CI, 0.44-3.69).

CONCLUSIONS

Sarcopenia is highly prevalent in patients with lung cancer (approximately one in two) and an important predictor of impaired OS in patients with SCLC or with different stages of NSCLC.

Evaluation of transcatheter heart valve biomaterials: Computational modeling using bovine and porcine pericardium

OBJECTIVE

The durability of bioprosthetic heart valve (BHV) devices, commonly made of bovine (BP) and porcine (PP) pericardium tissue, is partly limited by device calcification and tissue degeneration, which has been associated with pathological levels of mechanical stress. This study investigated the impacts of BP and PP tissues with different thicknesses and tissue mechanical properties in BHV applications.

METHODS

Second Harmonic Generation (SHG) imaging was employed to visualize the collagen fibers on each side of the pericardium. Structural constitutive modeling that incorporates collagen fiber distribution obtained from multiphoton microscopy for each tissue type were derived to characterize the corresponding biaxial mechanical testing data collected in a previous study. The models were verified through finite element (FE) simulations of the biaxial test and implemented in valve closing simulations.

RESULTS

Smooth side collagen fibers were found to correlate with the mechanical response. BHVs with adult (ABP) and calf (CBP) BP tissues had lower maximum principal stresses than those with PP and fetal (FBP) BP tissues. Collagen fiber orientation along the circumferential axis resulted in lower maximum principal stresses and more uniform and symmetric stress distributions throughout the valve.

CONCLUSIONS

The use of PP and FBP tissue resulted in higher peak stresses than ABP and CBP tissues in the given valve design. Additionally, ensuring collagen fiber orientation along the circumferential axis led to lower maximum stresses felt by the valve leaflets, which could also improve BHV durability.

Transcatheter versus surgical aortic valve replacement in low and intermediate risk patients with severe aortic stenosis: systematic review and meta-analysis of randomized controlled trials and propensity score matching observational studies

Background

To compare the outcome of transcatheter aortic valve replacement (TAVR) with surgical aortic valve replacement (SAVR) in low and intermediate risk patients with severe aortic stenosis (AS). Randomized controlled trials (RCT) and propensity score matching (PSM) studies compare TAVR with SAVR in patients at low and intermediate surgical risk.

Methods

Two authors searched relevant literature independently, then extracted data from the included studies, and assessed risk of bias and quality of study separately according to different study designs, besides that, the extracted data was analyzed via utilization of GRADE system to evaluate the quality of evidence separately.

Results

Overall 15 studies (5 RCTs, 10 PSM studies) with total 12,057 patients were selected. Mortality and disabling stroke during follow-up period were comparable between TAVR and SAVR (RR 1.09, 95% CI: 0.81 to 1.46; RR 0.7, 95% CI: 0.45 to 1.07, respectively), TAVR revealed to be superior to SAVR regarding acute kidney injury (AKI), and onset of new atrial fibrillation (AF) (RCT: high certainty; AKI in PSM: moderate certainty, AF in PSM: low certainty). These results of RCT and PSM studies are consistent. In RCT review, SAVR was better in the following aspects: aortic valve (AV) re-intervention (high certainty), vascular complications, pacemaker implantation (moderate certainty), but comparable in the following aspects: myocardial infarction (MI), aortic insufficient (AI) (moderate certainty), major bleeding (low certainty). In PSM review, SAVR revealed a better result in AI and vascular complications (high certainty), but in the aspects of AV re-intervention, pacemaker implantation, major bleeding and MI (low certainty), it was comparable.

Conclusions

TAVR is comparable to SAVR in terms of mortality and disabling stroke in severe AS patients at low and intermediate risk, but higher proportion of AV re-intervention observed in TAVR. Those results should encourage caution when extending the indications of TAVR into low risk patients, especially for young low risk patients.

Systematic review registration

PROSPERO CRD 42018112626.

Aortic valve repair or replacement in patients with aortic regurgitation: A systematic review and meta-analysis

OBJECTIVE

To systematically compare clinical outcomes between aortic valve repair and replacement in patients with aortic regurgitation.

METHODS

A comprehensive literature search was undertaken among the four major databases (PubMed, Embase, Scopus, and Ovid) to identify all published data comparing clinical outcomes of aortic valve repair vs replacement. Database searched from inception to November 2018.

RESULTS

A total of 1071 patients were analyzed in eight articles. Mean age was similar in both groups of patients (47.2 ± 12.8 vs 48.3 ± 12.7 years, P = 0.83, aortic valve repair and replacement, respectively). The preoperative left ventricular ejection fraction was better in the repair group (56.7% ± 4.8 vs 53.3% ± 4.2, P = 0.005). The rate of moderate-to-severe regurgitation and bicuspid aortic valve were similar in both cohorts (81% vs 78%, P = 0.90% and 58% vs 55%, P = 0.46). In-hospital and 1-year mortality was lower in repair cohort, although not reaching statistical significance (1.3% vs 3.6%, P = 0.12; 5.9% vs 9.3%, P = 0.77). Reoperation rate was higher in repair patients at 1 year (8.8% vs 3.7%, P = 0.03).

CONCLUSION

Aortic valve repair offers comparable perioperative outcomes to aortic valve replacement in aortic regurgitation patients at the expense of higher late reintervention rate. Larger trials with long-term follow-up are required to confirm the long-term benefits of aortic valve repair.

Detection and Prediction of Bioprosthetic Aortic Valve Degeneration

BACKGROUND

Bioprosthetic aortic valve degeneration is increasingly common, often unheralded, and can have catastrophic consequences.

OBJECTIVES

The authors sought to assess whether 18F-fluoride positron emission tomography (PET)-computed tomography (CT) can detect bioprosthetic aortic valve degeneration and predict valve dysfunction.

METHODS

Explanted degenerate bioprosthetic valves were examined ex vivo. Patients with bioprosthetic aortic valves were recruited into 2 cohorts with and without prosthetic valve dysfunction and underwent in vivo contrast-enhanced CT angiography, 18F-fluoride PET, and serial echocardiography during 2 years of follow-up.

RESULTS

All ex vivo, degenerate bioprosthetic valves displayed 18F-fluoride PET uptake that colocalized with tissue degeneration on histology. In 71 patients without known bioprosthesis dysfunction, 14 had abnormal leaflet pathology on CT, and 24 demonstrated 18F-fluoride PET uptake (target-to-background ratio 1.55 [interquartile range (IQR): 1.44 to 1.88]). Patients with increased 18F-fluoride uptake exhibited more rapid deterioration in valve function compared with those without (annualized change in peak transvalvular velocity 0.30 [IQR: 0.13 to 0.61] vs. 0.01 [IQR: -0.05 to 0.16] ms-1/year; p < 0.001). Indeed 18F-fluoride uptake correlated with deterioration in all the conventional echocardiographic measures of valve function assessed (e.g., change in peak velocity, r = 0.72; p < 0.001). Each of the 10 patients who developed new overt bioprosthesis dysfunction during follow-up had evidence of 18F-fluoride uptake at baseline (target-to-background ratio 1.89 [IQR: 1.46 to 2.59]). On multivariable analysis, 18F-fluoride uptake was the only independent predictor of future bioprosthetic dysfunction.

CONCLUSIONS

18F-fluoride PET-CT identifies subclinical bioprosthetic valve degeneration, providing powerful prediction of subsequent valvular dysfunction and highlighting patients at risk of valve failure. This technique holds major promise in the diagnosis of valvular degeneration and the surveillance of patients with bioprosthetic valves. (18F-Fluoride Assessment of Aortic Bioprosthesis Durability and Outcome [18F-FAABULOUS]; NCT02304276).

Results of mechanical versus tissue AVR: caution in young patients with tissue AVR

The first aortic valve prosthesis, implanted more than 50 years ago, was a mechanical prosthesis (ball-and-cage design). Over the ensuing decades, tissue prostheses and new mechanical designs were introduced to mitigate the need for anticoagulation with its associated side effects. Tissue and mechanical heart valve prostheses were compared in two head-to-head randomised control trials. Both of these confirmed that mechanical prostheses were durable but patients suffered anticoagulant-related bleeds. Patients who received a tissue prosthesis were more likely to suffer prosthetic dysfunction and require reoperation. This trend was stronger in younger patients. Since the publication of those two trials, several large retrospective studies using data from meta-analyses of published papers or registries have failed to show a survival advantage of either prostheses when implanted in the aortic position in younger patients. This equipoise has been reflected in the heart valve disease guidelines published by European and US societies. In recent years, the primacy of patient choice, the rapid increase in life expectancy of populations, the increased incidence of atrial fibrillation with requirement for anticoagulation, the advent of transcatheter techniques to treat degenerating tissue valves as well as advances in anticoagulant therapy and in new tissue and to a lesser extent mechanical prosthetic design continue to influence choice of aortic valve prosthesis in younger patients undergoing aortic valve replacement.

Patient-prosthesis mismatch following aortic valve replacement

Patient-prosthesis mismatch (PPM) occurs when an implanted prosthetic valve is too small for the patient; severe PPM is defined as an indexed effective orifice area (iEOA) <0.65 cm2/m2 following aortic valve replacement (AVR). This review examines articles from the past 10 years addressing the prevalence, outcomes and options for prevention and treatment of PPM after AVR. Prevalence of PPM ranges from 8% to almost 80% in individual studies. PPM is thought to have an impact on mortality, mainly in patients with severe PPM, although severe PPM accounts for only 10–15% of cases. Outcomes of patients with moderate PPM are not significantly different to those without PPM. PPM is associated with higher rates of perioperative stroke and renal failure and lack of left ventricular mass regression. Predictors include female sex, older age, hypertension, diabetes, renal failure and higher surgical risk score. PPM may be a marker of comorbidity rather than a risk factor for adverse outcomes. PPM should be suspected in patients with persistent cardiac symptoms after AVR when there is high prosthetic valve velocity or gradient and a small calculated effective orifice area. After exclusion of other causes of increased transvalvular gradient, re-intervention may be considered if symptoms persist and are unresponsive to medical therapy. However, this decision needs to consider the available options to relieve PPM and whether expected benefits justify the risk of intervention. The only effective intervention is redo surgery with implantation of a larger valve and/or annular enlargement. Therefore, focus needs to be on prevention.

Valve durability after transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) is a minimally invasive procedure to treat severe symptomatic aortic stenosis. While the TAVI procedure can be performed safely and provide excellent 5-year results, little is known about long-term durability. TAVI valves are composed of bioprosthetic leaflets are prone to deterioration, which are categorized as structural valve deterioration (SVD) and non-SVD. SVD refers to an intrinsic pathology of the leaflets or stent structure with mechanisms that include leaflet calcification, leaflet tear, stent fracture, or stent creep. Non-SVD processes include valve thrombosis, infective endocarditis and patient prosthesis mismatch. TAVI valves degenerate by similar mechanisms as bioprosthetic surgical aortic valves. Unique mechanisms that contribute to TAVI degeneration include valve crimpling, balloon expansion, stent under-expansion and valve thrombosis. The absence of a universally accepted definition of SVD poses a challenge in estimating valve durability. Traditional surgical bioprosthetic aortic valves have demonstrated excellent durability with clinically relevant SVD of 6.6% at 10-year follow up. Long-term durability of TAVI valves, however, remain poorly defined. From meta-analysis TAVI trials, SVD was estimated at 7% at 5 years. With iterative improvements in TAVI valve construction and deployment techniques, long-term durability may improve. Until long-term outcomes are better understood, TAVI should be used with caution in younger patients.

A computed tomography-based planning tool for predicting difficulty of minimally invasive aortic valve replacement

OBJECTIVES

Minimally invasive aortic valve replacement has proven its value over the last decade by its significant advancement and reduction in mortality, morbidity and admission time. However, minimally invasive aortic valve replacement is associated with some on-site difficulties such as limited aortic annulus exposure. Currently, computed tomography scans are used to evaluate the anatomical relationship among the intercostal spaces, ascending aorta and aortic valve prior to surgery. We hypothesized that quantitative measurements of access distance and access angle are associated with outcome and access difficulty.

METHODS

We introduce a novel minimally invasive aortic valve replacement planning prototype that allows automatic measurements of access angle, access distance and aortic annulus dimensions. The prototype visualizes these measurements on the chest cage as ISO contours. The association of these measures with outcome parameters such as extracorporeal circulation time, aortic cross-clamping time and access difficulty score was assessed. We included 14 patients who received a new valve by ministernotomy.

RESULTS

The mean access angle was 40.3 ± 5.1°. It was strongly associated with aortic cross-clamping time (Pearson correlation coefficient = 0.60, P = 0.02) and access difficulty score (Spearman's rank correlation coefficient = 0.57, P = 0.03). Access angles were significantly different between easy and difficult access groups (P = 0.03). There was no significant association between access distance and outcome parameters.

CONCLUSIONS

Access angle is strongly associated with procedure complexity. The automated presentation of this measure suggests added value of the prototype in clinical practice.

Tissue-Engineered Heart Valves: A Call for Mechanistic Studies

Heart valve disease carries a substantial risk of morbidity and mortality. Outcomes are significantly improved by valve replacement, but currently available mechanical and biological replacement valves are associated with complications of their own. Mechanical valves have a high rate of thromboembolism and require lifelong anticoagulation. Biological prosthetic valves have a much shorter lifespan, and they are prone to tearing and degradation. Both types of valves lack the capacity for growth, making them particularly problematic in pediatric patients. Tissue engineering has the potential to overcome these challenges by creating a neovalve composed of native tissue that is capable of growth and remodeling. The first tissue-engineered heart valve (TEHV) was created more than 20 years ago in an ovine model, and the technology has been advanced to clinical trials in the intervening decades. Some TEHVs have had clinical success, whereas others have failed, with structural degeneration resulting in patient deaths. The etiologies of these complications are poorly understood because much of the research in this field has been performed in large animals and humans, and, therefore, there are few studies of the mechanisms of neotissue formation. This review examines the need for a TEHV to treat pediatric patients with valve disease, the history of TEHVs, and a future that would benefit from extension of the reverse translational trend in this field to include small animal studies.

Standardized Definition of Structural Valve Degeneration for Surgical and Transcatheter Bioprosthetic Aortic Valves

Bioprostheses are prone to structural valve degeneration, resulting in limited long-term durability. A significant challenge when comparing the durability of different types of bioprostheses is the lack of a standardized terminology for the definition of a degenerated valve. This issue becomes especially important when we try to compare the degeneration rate of surgically inserted and transcatheter bioprosthetic valves. This document, by the VIVID (Valve-in-Valve International Data), proposes practical and standardized definitions of valve degeneration and provides recommendations for the timing of clinical and imaging follow-up assessments accordingly. Its goal is to improve the quality of research and clinical care for patients with deteriorated bioprostheses by providing objective and strict criteria that can be utilized in future clinical trials. We hope that the adoption of these criteria by both the cardiological and surgical communities will lead to improved comparability and interpretation of durability analyses.

Failed TAVI in TAVI Implantation: TAVI Dislocation Followed by Ensuing Surgical Graft Resection

We are presenting a case report of failed valve-in-valve treatment of severe aortic stenosis. A control ultrasonography after TAVI implantation revealed a severe aortic regurgitation of the graft which was subsequently unresolved with postimplantation dilatation. Second TAVI was implanted with cranial dislocation to the aortic root. Patient underwent a CT examination to clarify the TAVI in TAVI position. Patient underwent a surgical resection of TAVI with implantation of biological aortic valve prosthesis. In situations where TAVI treatment fails or is complicated beyond the possibility of endovascular repair, surgical intervention despite its higher risks is the preferred choice.

Transcatheter versus surgical aortic valve replacement in patients with severe aortic stenosis at low and intermediate risk: systematic review and meta-analysis

OBJECTIVE

 To examine the effect of transcatheter aortic valve implantation (TAVI) versus surgical replacement of an aortic valve (SAVR) in patients with severe aortic stenosis at low and intermediate risk of perioperative death.

DESIGN

 Systematic review and meta-analysis DATA SOURCES:  Medline, Embase, and Cochrane CENTRAL.

STUDY SELECTION

 Randomized trials of TAVI compared with SAVR in patients with a mean perioperative risk of death <8%.

REVIEW METHODS

 Two reviewers independently extracted data and assessed risk of bias for outcomes important to patients that were selected a priori by a parallel guideline committee, including patient advisors. We used the GRADE system was used to quantify absolute effects and quality of evidence.

RESULTS

 4 trials with 3179 patients and a median follow-up of two years were included. Compared with SAVR, transfemoral TAVI was associated with reduced mortality (risk difference per 1000 patients: -30, 95% confidence interval -49 to -8, moderate certainty), stroke (-20, -37 to 1, moderate certainty), life threatening bleeding (-252, -293 to -190, high certainty), atrial fibrillation (-178, -150 to -203, moderate certainty), and acute kidney injury (-53, -39 to -62, high certainty) but increased short term aortic valve reintervention (7, 1 to 21, moderate certainty), permanent pacemaker insertion (134, 16 to 382, moderate certainty), and moderate or severe symptoms of heart failure (18, 5 to 34, moderate certainty). Compared with SAVR, transapical TAVI was associated higher mortality (57, -16 to 153, moderate certainty, P=0.015 for interaction between transfemoral versus transapical TAVI) and stroke (45, -2 to 125, moderate certainty, interaction P=0.012). No study reported long term follow-up, which is particularly important for structural valve deterioration.

CONCLUSIONS

 Many patients, particularly those who have a shorter life expectancy or place a lower value on the risk of long term valve degeneration, are likely to perceive net benefit with transfemoral TAVI versus SAVR. SAVR, however, performs better than transapical TAVI, which is of interest to patients who are not candidates for transfemoral TAVI.

SYSTEMATIC REVIEW REGISTRATION

 PROSPERO CRD42016042879.