Possible Subclinical Leaflet Thrombosis in Bioprosthetic Aortic Valves

Safety and Efficacy of Non-Vitamin K Oral Anticoagulant Use Early After Cardiac Surgery: A Systematic Review

OBJECTIVE

To determine the safety and efficacy of non-vitamin K oral anticoagulants (NOACs) initiated early after cardiac surgery.

DATA SOURCES:

Cochrane Central Register of Controlled Trials, EMBASE, and MEDLINE (database inception to January 20, 2021), www.clinicaltrials.gov, www.who.int/ictrp/search/en/, NOAC trial registries, and bibliographies of relevant guidelines and other reviews were used.

STUDY SELECTION AND DATA EXTRACTION

Observational studies and randomized controlled trials (RCTs) that initiated NOACs within the index hospitalization and that reported bleeding for the primary outcome were included.

DATA SYNTHESIS

A total of 6 cohort studies, 1 RCT, and 3 ongoing RCTs were included. Most studies were single-centered, limited to postoperative atrial fibrillation after coronary artery bypass grafting, and with 30-day follow-up; few studies included patients with isolated bioprosthetic valve replacement or valve repair. Bleeding risk varied (0%-28.6%), and all but one study showed no significantly higher risk with NOAC compared with warfarin.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Overall, NOACs were used in 26% to 37.5% of patients early after cardiac surgery. Starting a NOAC on postoperative day 4 appeared to have similar bleeding rates compared with warfarin, but clinical application is limited by heterogeneity of outcome definitions, confounding, and bias. Compared with warfarin, NOACs may have similar thromboembolism risk, reduced length of stay, and cost.

CONCLUSIONS

There is limited evidence to guide NOAC use early after cardiac surgery. Three ongoing randomized trials will add to the literature and provide guidance for clinicians on whether, in whom, when, and how to use NOACs safely early after cardiac surgery.

Narrative review of the contemporary surgical treatment of unicuspid aortic valve disease

Unicuspid aortic valve disease (UAVD) is a frequent and long-lasting challenge for adult congenital heart disease centers. UAVD patients become usually symptomatic in their twenties or thirties and require a surgical treatment plan which should respect their complete lifespan combined with an adequate quality of life. Unfortunately, all current surgical strategies of congenital aortic valve disease bear some important limitations: (I) Aortic valve replacement using bioprosthetic valves is associated with early structural degeneration and leads frequently to re-operations. (II) Mechanical valves are commonly associated with lifelong risk of severe bleeding due to oral anticoagulation. (III) Using a pulmonary autograft (i.e., Ross procedure) for aortic valve replacement is associated with excellent long-term results in non-elderly patients. However, failure of pulmonary autograft or pulmonary homograft may require re-operations. (IV) Aortic valve repair or Ozaki procedure is only performed in a few heart centers worldwide and is associated with a limited reproducibility and early patch degeneration, suture dehiscence or increased risk of endocarditis. In contrast to degenerative tricuspid aortic valve disease, UAVD remains relatively understudied and reports on UAVD treatment are rare and usually limited to retrospective single-center observations. For this review, we searched PubMed for papers in the English language by using the search words unicuspid aortic valve, congenital aortic valve, Ross procedure, Ozaki procedure, aortic valve repair, mechanical/bioprosthetic aortic replacement, homograft. We read the abstracts of relevant titles to confirm their relevance, and the full papers were then extracted. References from extracted papers were checked for additional relevant reports. This review summarizes current surgical treatment strategies for UAVD including aortic valve replacement using bioprosthetic or mechanical valves, homografts, pulmonary autografts (i.e., Ross procedure) and aortic valve repair techniques for UAV. Furthermore, Ozaki procedure will be discussed.

Detecting native and bioprosthetic aortic valve disease using 18F-sodium fluoride: Clinical implications

Calcific aortic valve disease is the most common valvular disease and confers significant morbidity and mortality. There are currently no medical therapies that successfully halt or reverse the disease progression, making surgical replacement the only treatment currently available. The majority of patients will receive a bioprosthetic valve, which themselves are prone to degeneration and may also need replaced, adding to the already substantial healthcare burden of aortic stenosis. Echocardiography and computed tomography can identify late-stage manifestations of the disease process affecting native and bioprosthetic aortic valves but cannot detect or quantify early molecular changes. 18F-fluoride positron emission tomography, on the other hand, can non-invasively and sensitively assess disease activity in the valves. The current review outlines the pivotal role this novel molecular imaging technique has played in improving our understanding of native and bioprosthetic aortic valve disease, as well as providing insights into its feasibility as an important future research and clinical tool.

A computational study of the hemodynamics of bioprosthetic aortic valves with reduced leaflet motion

We employ a reduced degree-of-freedom aortic valve model to investigate the flow physics associated with early-stage reduced leaflet motion in bioprosthetic aortic valves. The model is coupled with a sharp-interface immersed boundary based incompressible flow solver to efficiently simulate the fluid-structure interaction. A total of 19 cases of flow through aortic valves with varying degrees of reduced leaflet motion (RLM) are considered. The characteristics of the aortic jet and the consequent aorta wall loading patterns are analyzed. Our results show that asymmetric RLM tilts the aortic jet and leads to large reverse and recirculating flow regions downstream from leaflets with restricted mobility. The changes in flow patterns increase wall pressure and shear stress fluctuations, and result in asymmetric oscillating shear on the aorta wall. These findings have implications for auscultation based diagnosis of this condition as well as the health of the aorta.

Bioprosthetic valve oversizing is associated with increased risk of valve thrombosis following TAVR

BACKGROUND

Hypoattenuating leaflet thickening (HALT), the radiographic manifestation of transcatheter heart valve thrombosis, is commonly identified following transcatheter aortic valve replacement (TAVR) and associated with increased risk of stroke and structural valve deterioration. While anticoagulation effectively resolves HALT, routine use remains controversial. We aimed to identify hemodynamic, anatomic, and comorbid predictors of HALT.

METHODS

We evaluated consecutive patients with severe aortic stenosis who underwent TAVR with Edwards SAPIEN 3 bioprosthesis at a single center between June 1, 2018 and October 30, 2019. Patients on anticoagulation and those receiving valve-in-valve were excluded. Clinically driven computed tomography (CT) imaging was performed to assess for HALT at the discretion of the treating valve team.

RESULTS

A total of 78 patients with a mean age of 78 ± 10 years and STS risk score 5.5 ± 3.3% were analyzed. HALT was identified in 11 (14.1%) patients. Compared to controls, those with HALT had smaller annular areas, 435 ± 57 mm² vs. 489 ± 79 mm² (p = .032), but received comparable size valves. In multivariate regression, valve oversizing by more than 20% was associated with increased risk of HALT, OR 23.5, 95% CI 2.5-223, (p = .006). After initiation of anticoagulation, patients with HALT had similar rates of stroke, major bleeding, and all-cause mortality out to an average of 243 days.

CONCLUSIONS

In this pragmatic study of patients undergoing TAVR with SAPIEN 3 valves, we report the novel finding that oversizing by more than 20% was independently associated with increased risk of HALT. These findings warrant confirmation in larger and prospective trials.

Impact of BASILICA on the thrombogenicity potential of valve-in-valve implantations

Subclinical leaflet thrombosis is becoming a major concern in valve-in-valve procedures, whereby a transcatheter aortic valve device is deployed inside a failed bioprosthetic surgical valve. Blood flow stagnation and prolonged residence times in the neo-sinuses have been suggested as possible explanations for leaflet thrombosis. The BASILICA technique, which was originally developed to treat coronary flow obstruction, has also been proposed as an alternative to reduce the risk of thrombus formation. The aim of this study is to understand the impact of BASILICA on the valve-in-valve thrombogenicity using computational fluid dynamics simulations. To this end, two Eulerian and two Lagrangian approaches were employed to estimate near-wall stagnation measures in eight valve-in-valve models. The models included an intact or lacerated Sorin Mitroflow surgical valve, and either a SAPIEN or Evolut transcatheter aortic valve device. The Lagrangian approaches predicted a high number of particles and vortices concentration in the proximal areas of the neo-sinuses, while the Eulerian approaches did so in the distal areas. As a consequence, this study demonstrated that Lagrangian approaches are better predictors of subclinical leaflet thrombosis, since they match experimental and clinical findings. Additionally, the SAPIEN valve possess a higher risk for developing leaflet thrombosis, and two lacerations are shown to provide the best results in terms of development of vortices and accumulation of particles within the neo-sinuses. This study highlights the potential of computational modeling in aiding clinicians in their decision-making in valve-in-valve and BASILICA procedures.

2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This executive summary of the valvular heart disease guideline provides recommendations for clinicians to diagnose and manage valvular heart disease as well as supporting documentation to encourage their use.

METHODS

A comprehensive literature search was conducted from January 1, 2010, to March 1, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, Cochrane, Agency for Healthcare Research and Quality Reports, and other selected database relevant to this guideline. Structure: Many recommendations from the earlier valvular heart disease guidelines have been updated with new evidence and provides newer options for diagnosis and treatment of valvular heart disease. This summary includes only the recommendations from the full guideline which focus on diagnostic work-up, the timing and choice of surgical and catheter interventions, and recommendations for medical therapy. The reader is referred to the full guideline for graphical flow charts, text, and tables with additional details about the rationale for and implementation of each recommendation, and the evidence tables detailing the data considered in developing these guidelines.

The International Society for Minimally Invasive Cardiothoracic Surgery Expert Consensus Statement on Transcatheter and Surgical Aortic Valve Replacement in Low- and Intermediate-Risk Patients: A Meta-Analysis of Randomized and Propensity-Matched Studies

OBJECTIVE

There is an increasing amount of evidence supporting use of transcatheter aortic valve replacement (TAVR) for treatment of aortic stenosis in patients at low or intermediate risk for surgical aortic valve replacement (SAVR). TAVR is now approved for use in all patient cohorts. Despite this, there remains debate about the relative efficacy of TAVR compared with SAVR in lower-risk cohorts and various subgroups of patients. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) and propensity-matched trials to guide a consensus among expert cardiologists and surgeons.

METHODS

Studies comparing TAVR and SAVR in low- and intermediate-risk patients were identified by a thorough search of the major databases. Mortality, stroke, and other perioperative outcomes were assessed at 30 days and 1 year.

RESULTS

Early mortality was lower in TAVR compared to SAVR in RCTs, but not propensity-matched studies in low-risk cohorts (0.66% vs 1.5%; odds ratio [OR] = 0.44, 95% confidence interval [CI] 0.20 to 0.98, I² = 0%). No difference in mortality between TAVR and SAVR was identified in intermediate-risk patients at early or later time points. Incidence of perioperative stroke in 3 low-risk RCTs was significantly lower in TAVR (0.4%) than SAVR (1.4%; OR = 0.33, 95% CI 0.13 to 0.81, I² = 0%). There was no difference in stroke for intermediate-risk patients between TAVR and SAVR. The expert panel of cardiologists and cardiac surgeons provided recommendations for TAVR and SAVR in various clinical scenarios.

CONCLUSIONS

In RCTs comparing TAVR and SAVR in low-risk patients, early mortality and stroke were lower in TAVR, but did not differ at 1 year. There was no difference in mortality and stroke in intermediate-risk patients. The Multidisciplinary Heart Team must consider individual patient characteristics and preferences when recommending TAVR or SAVR. The decision must consider the long-term management of each patient's aortic valve disease.

Fluid-structure coupled biotransport processes in aortic valve disease

Biological transport processes near the aortic valve play a crucial role in calcific aortic valve disease initiation and bioprosthetic aortic valve thrombosis. Hemodynamics coupled with the dynamics of the leaflets regulate these transport patterns. Herein, two-way coupled fluid-structure interaction (FSI) simulations of a 2D bicuspid aortic valve and a 3D mechanical heart valve were performed and coupled with various convective mass transport models that represent some of the transport processes in calcification and thrombosis. Namely, five different continuum transport models were developed to study biochemicals that originate from the blood and the leaflets, as well as residence-time and flow stagnation. Low-density lipoprotein (LDL) and platelet activation were studied for their role in calcification and thrombosis, respectively. Coherent structures were identified using vorticity and Lagrangian coherent structures (LCS) for the 2D and 3D models, respectively. A very close connection between vortex structures and biochemical concentration patterns was shown where different vortices controlled the concentration patterns depending on the transport mechanism. Additionally, the relationship between leaflet concentration and wall shear stress was revealed. Our work shows that blood flow physics and coherent structures regulate the flow-mediated biological processes that are involved in aortic valve calcification and thrombosis, and therefore could be used in the design process to optimize heart valve replacement durability.

Current Indications for Transcatheter Mitral Valve Replacement Using Transcatheter Aortic Valves

Use of transcatheter mitral valve replacement (TMVR) using transcatheter aortic valves in clinical practice is limited to patients with failing bioprostheses and rings or mitral valve disease associated with severe mitral annulus calcification. Whereas the use of valve-in-valve TMVR appears to be a reasonable alternative to surgery in patients at high surgical risk, much less evidence supports valve-in-ring and valve-in-mitral annulus calcification interventions. Data on the results of TMVR in these settings are derived from small case series or voluntary registries. This review summarizes the current evidence on TMVR using transcatheter aortic valves in clinical practice from the characteristics of the TMVR candidates, screening process, performance of the procedure, and description of current results and future perspectives. TMVR using dedicated devices in native noncalcified mitral valve diseases is beyond the scope of the article.

Rationale and design of the ADAPT-TAVR trial: a randomised comparison of edoxaban and dual antiplatelet therapy for prevention of leaflet thrombosis and cerebral embolisation after transcatheter aortic valve replacement

INTRODUCTION

Optimal antithrombotic strategy following transcatheter aortic valve replacement (TAVR) is still unknown. We hypothesised that the direct factor Xa inhibitor edoxaban can potentially prevent subclinical leaflet thrombosis and cerebral embolisation compared with conventional dual antiplatelet therapy (DAPT) in patients undergoing TAVR.

METHODS AND ANALYSIS

The ADAPT-TAVR trial is an international, multicentre, randomised, open-label, superiority trial comparing edoxaban-based strategy and DAPT strategy in patients without an indication for oral anticoagulation who underwent successful TAVR. A total of 220 patients are randomised (1:1 ratio), 1-7 days after successful TAVR, to receive either edoxaban (60 mg daily or 30 mg daily if patients had dose-reduction criteria) or DAPT using aspirin (100 mg daily) plus clopidogrel (75 mg daily) for 6 months. The primary endpoint was an incidence of leaflet thrombosis on four-dimensional, volume-rendered cardiac CT imaging at 6 months post-TAVR. The key secondary endpoints were the number of new lesions and new lesion volume on brain diffusion-weighted MRI and the changes in neurological and neurocognitive function assessment between immediate post-TAVR and 6 months of study drug administration. Detailed clinical information on thromboembolic and bleeding events were also assessed.

ETHICS AND DISSEMINATION

Ethic approval has been obtained from the Ethics Committee/Institutional Review Board of Asan Medical Center (approval number: 2017-1317) and this trial is also approved by National Institute of Food and Drug Safety Evaluation of Republic of Korea (approval number: 31511). Results of this study will be disseminated in scientific publication in reputed journals.

TRIAL REGISTRATION NUMBER

NCT03284827.

Early Postoperative Thrombosis of Transcatheter Aortic Valve-in-Valve Prosthesis

Valve-in-valve transcatheter aortic valve replacement (ViV-TAVR) has been popularized as an attractive alternative to redo surgical aortic valve replacement for bioprosthetic valve dysfunction. Acute valve thrombosis has been occasionally described after ViV-TAVR. Lack of anticoagulant therapy has been always considered a crucial risk factor. This report describes a rare case of early postoperative fatal ViV-TAVR thrombosis despite adequate anticoagulation in addition to dual antiplatelet therapy.

A review of indications and comorbidities in which warfarin may be the preferred oral anticoagulant

WHAT IS KNOWN AND OBJECTIVE

Direct oral anticoagulants (DOACs) are increasingly prescribed instead of warfarin for chronic anticoagulation for ease of dosing, fewer interactions, and less stringent monitoring. However, it is important to consider indications and comorbidities for which warfarin is still the preferred anticoagulant. This review aims to capture these clinical scenarios in which warfarin may still be preferred over DOACs.

METHODS

We undertook a comprehensive literature search using the PubMed database. Key search terms were based on DOAC clinical trial exclusion criteria, as well as indications and conditions in which the use of DOACs for anticoagulation has suggested harm. Society guidelines and tertiary literature were used to inform expert opinion where necessary. Studies were included if they investigated the use of DOACs or warfarin in the identified indications or conditions.

RESULTS AND DISCUSSION

Currently, evidence for the use of warfarin over DOACs for anticoagulation is strongest for patients with prosthetic valves, antiphospholipid syndrome, or a high risk of gastrointestinal bleeding. For several clinical situations, including mitral stenosis, obesity, altered gastrointestinal anatomy, pulmonary arterial hypertension, renal or hepatic impairment, and left ventricular thrombus, evidence is lacking but may eventually support the use of DOACs. Depending on indication and condition, appropriateness of DOAC use may vary by agent.

WHAT IS NEW AND CONCLUSION

New evidence continues to support new indications and conditions in which DOACs may be appropriate to use for anticoagulation. There are key clinical scenarios, however, in which emerging literature continues to support warfarin as the preferred anticoagulant.

Meta-Analysis of Bioprosthetic Valve Thrombosis After Transcatheter Aortic Valve Implantation

Bioprosthetic valve thrombosis may complicate transcatheter aortic valve implantation (TAVI). This meta-analysis sought to evaluate the prevalence and clinical impact of subclinical leaflet thrombosis (SLT) and clinical valve thrombosis (CVT) after TAVI. We summarized diagnostic strategies, prevalence of SLT and/or CVT and estimated their impact on the risk of all-cause death and stroke. Twenty studies with 12,128 patients were included. The prevalence of SLT and CVT was 15.1% and 1.2%, respectively. The risk of all-cause death was not significantly different between patients with SLT (relative risk [RR] 0.77; p = 0.22) and CVT (RR 1.29; p = 0.68) compared with patients without. The risk of stroke was higher in patients with CVT (RR 7.51; p <0.001) as compared with patients without, while patients with SLT showed no significant increase in the risk of stroke (RR 1.81; p = 0.17). Reduced left ventricular function was associated with increased prevalence, while oral anticoagulation was associated with reduced prevalence of bioprosthetic valve thrombosis. Bioprosthetic valve thrombosis is frequent after TAVI, but does not increase the risk of death. Clinical valve thrombosis is associated with a significantly increased risk of stroke. Future studies should focus on prevention and treatment of bioprosthetic valve thrombosis.

Antithrombotic selection in patients undergoing transcatheter aortic valve replacement

PURPOSE

Clinical controversy regarding the most appropriate antithrombotic regimen after transcatheter aortic valve replacement remains. Current evidence, guidelines, and recommendations are discussed.

SUMMARY

Antithrombotic selection following transcatheter aortic valve replacement depends on a variety of patient-specific factors. For patients without a preexisting indication for anticoagulation, initial trials employed dual antiplatelet therapy as the postprocedural therapy of choice. Newer studies in this patient population, however, suggest single antiplatelet therapy reduces bleeding events without sacrificing ischemic protection. In patients with a preexisting indication for anticoagulation, warfarin plus single antiplatelet therapy, as opposed to triple antithrombotic therapy, offered similar ischemic protection while reducing clinically significant bleeding. Warfarin monotherapy was associated with a further reduction in bleeding events. One trial demonstrated the safety and efficacy of using apixaban in patients with concomitant atrial fibrillation; however, routine use of rivaroxaban increased adverse cardiac and bleeding events, leaving the utility of direct-acting oral anticoagulants in question.

CONCLUSION

Available evidence and current guidelines point to a lack of consensus regarding antithrombotic selection after transcatheter aortic valve replacement. Patient-specific factors and comorbidities must be considered when tailoring therapy, with an emphasis on balancing thrombotic and bleeding risks.

Safety and efficacy of repeat transcatheter aortic valve replacement for the treatment of transcatheter prosthesis dysfunction

Introduction: Transcatheter aortic valve replacement (TAVR) has recently expanded toward the treatment of younger patients with lower surgical risk and longer life expectancy. Thus, transcatheter heart valve (THV) durability has become a central issue, and an important increase in the number of TAVR-in-TAVR is expected in the coming years. Areas covered: Overview of the current status of TAVR-in-TAVR for the treatment of THV dysfunction, focusing on safety and efficacy of repeat TAVR procedures. Expert opinion: An accurate analysis of the pre-procedure cardiac computed tomography, incorporating new parameters such as the position of the top of the first THV in relation to the sinotubular-junction, will be necessary to assess the risk of coronary occlusion. Subsequent coronary angiography will be necessary in a proportion of TAVR-in-TAVR patients, but coronary access may be very difficult or even impossible in some of them. Therefore, the choice between TAVR and SAVR in young low-risk patients should incorporate the potential need for treating coronary events at mid- to long-term follow-up. Likewise, the choice of the valve type and the implantation position at the time of the first TAVR procedure should take into account the possibility of TAVR-in-TAVR in the future.Abbreviations ACS: acute coronary syndrome; CO: coronary obstruction; EOA: effective orifice area; SAVR: surgical aortic valve replacement; SVD: structural valve degenerationTAVR: transcatheter aortic valve replacement; THV: transcatheter heart valve.

Over 15 years: the advancement of transcatheter aortic valve replacement

The management of aortic stenosis has been revolutionized by transcatheter aortic valve replacement (TAVR). Initially only undertaken in patients at prohibitive or high surgical risk, as the evidence base and indications have expanded, TAVR is now approved and undertaken in patients at all risk levels. Evolution of valve technology, delivery systems and pathways for patient work-up have been rapid, with associated reductions in the complication profile, particularly vascular complications. Challenges remain as TAVR continues to advance, however, specifically achieving further reduction in paravalvular regurgitation, the requirement for permanent pacemaker implantation, and balancing the risks of thrombosis and bleeding. In this review, we outline the historical advances leading to contemporary TAVR practice, and discuss the future trajectory.

Transcatheter Aortic Valve Thrombogenesis: A Foreign Materials Perspective

PURPOSE

The initiation of thrombus formation in transcatheter aortic valves (TAVs) is not well understood. The foreign material components of a TAV may play a key role in TAV thrombogenesis. The goal of this study was to evaluate the thrombogenic potential of a TAV (entire valve) and its stent (with skirt).

METHODS

Blood was collected from eight human donors with citrate anticoagulation and later reconstituted with calcium chloride. A low-volume steady flow loop (flow rate = 0.8 L/min) was designed to facilitate three separate conditions (experimental duration = 1 h) per donor blood: (1) control (n = 8), (2) stent-with-skirt (leaflets removed from a 23 mm SAPIEN XT valve; n = 8) and (3) entire valve (an intact 23 mm SAPIEN XT valve; n = 8). Samples were collected at the start and end of each experiment. Serum D-Dimer and thrombin-antithrombin (TAT) concentrations were measured as markers of thrombogenicity.

RESULTS

There was no significant change in serum D-Dimer and TAT concentration with time for the control group. An increasing trend in D-Dimer and TAT concentration was observed with time for the stent-with-skirt group. Interestingly, there was a decreasing trend in serum D-Dimer and TAT concentration with time for the entire valve (leaflet dominating) group. Moreover, changes in D-Dimer and TAT concentration were significantly different between the stent-with-skirt and entire valve (leaflet dominating) groups.

CONCLUSION

Stent-with-skirt was found to impart the most prominent thrombogenic effect, indicating the significance of blood-stent and blood-skirt interactions in TAV thrombosis.

Acute myocardial infarction associated with prosthetic valve leaflet thrombosis after transcatheter aortic valve implantation: a case report

BACKGROUND

Fatal thrombo-embolic events like cerebral stroke or myocardial infarction are rare complications of prosthetic heart valve leaflet thrombosis. Nevertheless, prevention and management of leaflet thrombosis is gaining increased attention, particularly with the widespread adoption of transcatheter heart valves.

CASE SUMMARY

We herein present the case of a 79-year-old man who had undergone a transcatheter aortic valve implantation procedure. Seven months later, he presented with a non-ST-segment elevation myocardial infarction. Coronary angiography did not reveal obstructive lesions. A dedicated cardiac computed tomography scan showed thrombosis of both right- and non-coronary leaflets of the prosthetic aortic valve, while prosthetic valve function was normal on echocardiography. Transmural myocardial infarction lesions in the midventricular and apical inferior wall were detected by cardiac magnetic resonance imaging.

DISCUSSION

Subclinical leaflet thrombosis of prosthetic aortic valves is a common finding. In this case report, we show that myocardial infarction presumably due to leaflet thrombosis was the first symptom in an otherwise asymptomatic patient. This finding raises the question of the validity in distinguishing between subclinical and clinical leaflet thrombosis based on prosthetic valve function.

Numerical models for assessing the risk of leaflet thrombosis post-transcatheter aortic valve-in-valve implantation

Leaflet thrombosis has been suggested as the reason for the reduced leaflet motion in cases of hypoattenuated leaflet thickening of bioprosthetic aortic valves. This work aimed to estimate the risk of leaflet thrombosis in two post-valve-in-valve (ViV) configurations, using five different numerical approaches. Realistic ViV configurations were calculated by modelling the deployments of the latest version of transcatheter aortic valve devices (Medtronic Evolut PRO, Edwards SAPIEN 3) in the surgical Sorin Mitroflow. Computational fluid dynamics simulations of blood flow followed the dry models. Lagrangian and Eulerian measures of near-wall stagnation were implemented by particle and concentration tracking, respectively, to estimate the thrombogenicity and to predict the risk locations. Most of the numerical approaches indicate a higher leaflet thrombosis risk in the Edwards SAPIEN 3 device because of its intra-annular implantation. The Eulerian approaches estimated high-risk locations in agreement with the wall sheer stress (WSS) separation points. On the other hand, the Lagrangian approaches predicted high-risk locations at the proximal regions of the leaflets matching the low WSS magnitude regions of both transcatheter aortic valve implantation models and reported clinical and experimental data. The proposed methods can help optimizing future designs of transcatheter aortic valves with minimal thrombotic risks.

Quantification of hypo-attenuated leaflet thickening after transcatheter aortic valve implantation: clinical relevance of hypo-attenuated leaflet thickening volume

AIMS

Our aim was to establish an objective, quantitative methodology for volumetric hypo-attenuated leaflet thickening (HALT) diagnosis and evaluate its clinical significance.

METHODS AND RESULTS

We prospectively enrolled 144 patients who underwent transcatheter aortic valve implantation (TAVI) between 2011 and 2016. At inclusion, cardiac computed tomography angiography (CTA), transthoracic echocardiography, and brain magnetic resonance imaging (MRI) were performed. We quantified HALT on CTA datasets by segmenting the inner volume of TAVI frame at the level of leaflets and extracted voxels between a threshold of -200 to 200 HU based on prior recommendation. The median HALT volume was 72 [inter-quartile range (IQR): 1-154] mm3 (intra- and inter-reader agreement: intra-class correlation coefficient = 0.92 and 0.94, respectively) and 79% (n = 87/111) of the patients had HALT >0 mm3. In multivariate linear regression, oral anti-coagulation (β: -0.32; 95% CI: -0.62 to -0.01; P = 0.004) and history of myocardial infarction (β: 0.32; 95% CI: 0.01-0.63; P = 0.043) were associated with HALT quantity. Log-transformed HALT volume was associated with elevated (>13 mmHg) aortic mean gradient (AMG, OR: 12.85; 95% CI: 1.96-152.93; P = 0.021) and moderate-to-severe valvular degeneration (AMG ≥ 20 mmHg or ΔAMG ≥ 10 mmHg; OR: 10.56; 95% CI: 1.44-148.71; P = 0.046) but did not predict ischaemic brain lesions on MRI or all-cause death after a median follow-up of 29 (IQR: 11-29) months (all P > 0.05).

CONCLUSION

Through systematic analysis of asymptomatic patients with TAVI, an objective and reproducible methodology was feasible for volumetric measurement of HALT. Anti-coagulation might have a protective effect against HALT. Ischaemic brain lesions and all-cause death were not associated with HALT; nevertheless, it might deteriorate prosthesis function due to its association with elevated AMG.

CLINICAL TRIAL REGISTRATION

http//:www.ClinicalTrials.gov; NCT02826200.

Glutaraldehyde and 2,3-butanediol treatment of bovine pericardium for aortic valve bioprosthesis in sheep: a preliminary study

Background

Bovine pericardium can be used for cardiovascular repair surgeries, but challenges involving biocompatibility and durability remain. This study aimed to carry out pre-clinical testing of aortic valve replacement using an aortic valve prosthesis made of bovine pericardium modified with glutaraldehyde (GA) and 2,3-butanediol (BD).

Methods

The mechanical, plasma protein adsorption, platelet adhesion, collagenase digestion, and ninhydrin properties of the material (control vs. GA vs. GA + BD) were tested. All 3 tissues were implanted in rats and observed after 8 weeks under microscopy with alizarin red staining for calcification. Aortic valves made from the fully-treated material were implanted in sheep. A commercial bioprosthesis was used as control. Effectiveness and safety indicators were observed at 180 days after implantation.

Results

Compared with the control group, the GA + BD material showed higher elongation at breaking and tensile load (both P<0.05), lower plasma protein adsorption, lower platelet adhesion, lower collagenase digestion, lower ninhydrin value, and higher cross-linking (all P<0.05). After implantation in rat models, the GA + BD material showed little or no dissolution; there was no obvious calcification; and it was surrounded by a small amount of fibrosis, with peripheral capillary proliferation. After implantation in sheep models, the aortic valve leaflets of the experimental animals freely opened and closed, their surface was smooth, and no abnormal echo was observed. The echocardiographic results and hemodynamic were comparable between the two groups. All safety parameters were normal.

Conclusions

Modification of bovine pericardium with GA and BD results in a biomaterial with favorable properties for use as an aortic valve prosthesis.

Expansion of TAVR into Low-Risk Patients and Who to Consider for SAVR

Transcatheter aortic valve replacement (TAVR) has revolutionized the treatment of severe aortic stenosis (AS) over the last decade. The results of the Placement of Aortic Transcatheter Valves (PARTNER) 3 and Evolut Low Risk trials demonstrated the safety and efficacy of TAVR in low-surgical-risk patients and led to the approval of TAVR for use across the risk spectrum. Heart teams around the world will now be faced with evaluating a deluge of younger, healthier patients with severe AS. Prior to the PARTNER 3 and Evolut Low Risk studies, this heterogenous patient population would have undergone surgical aortic valve replacement (SAVR). It is unlikely that TAVR will completely supplant SAVR for the treatment of severe AS in patients with a low surgical risk, as SAVR has excellent short- and long-term outcomes and years of durability data. In this review, we outline the critical role that SAVR will continue to play in the treatment of severe AS in the post-PARTNER 3/Evolut Low Risk era.

Predictors and Biomarkers of Subclinical Leaflet Thrombosis after Transcatheter Aortic Valve Implantation

Transcatheter aortic valve implantation (TAVI) is a recent revolutionary treatment for high-risk patients with severe aortic stenosis who are not suitable for surgery, expanding to intermediate and low-risk patients. Valve leaflet thrombosis (LT) is a potentially fatal complication after TAVI. The incidence of subclinical LT is as high as 25% among patients in the first year after TAVI. Subclinical LT may evolve into symptomatic thrombosis or lead to premature bioprosthesis degeneration, increasing the risk of neurological complications. Because imaging-based methods have limited sensitivity to detect subclinical LT, there is an urgent need for predictors and biomarkers that would make it possible to predict LT after TAVI. Here, we summarize recent data regarding (i) patient-related, (ii) procedure-related, (iii) blood-based and (iv) imaging predictors and biomarkers which might be useful for the early diagnosis of subclinical LT after TAVI. Prevention of LT might offer an opportunity to improve risk stratification and tailor therapy after TAVI.

In-Vitro Assessment of the Effects of Transcatheter Aortic Valve Leaflet Design on Neo-Sinus Geometry and Flow

Transcatheter aortic valve (TAV) leaflet thrombosis is a clinical risk with potentially fatal consequences. Studies have identified neo-sinus flow stasis as a cause of leaflet thrombosis. Flow stasis is influenced by the TAV leaflets, which affect the local fluid dynamics in the aortic sinus and neo-sinus. This study evaluated the effects of TAV leaflet features on the neo-sinus flow as a measure of leaflet thrombosis risk. Five TAVs of varied leaflet length and insertion height were tested in a simulator. Hydrodynamics and leaflet kinematics through en-phase imaging were quantified. Velocity fields were assessed using high-speed particle image velocimetry. Regions of flow stasis and particle residence times (PRTs) were quantified. TAVs with shorter leaflet length exhibited larger orifice areas and lower transvalvular pressure gradients. Shorter leaflet length and increased leaflet insertion TAVs additionally exhibited lower neo-sinus PRTs (0.44 ± 0.21 vs 2.83 ± 0.48 cycles, p < 0.05) and higher neo-sinus peak velocities (0.15 ± 0.009 vs 0.07 ± 0.005 m/s, p < 0.05) than TAVs with longer leaflet length and lower leaflet insertion. The average neo-sinus volume positively correlated with PRT(r = 0.810, p < 0.001), and extent of flow stasis (r = 0.682, p < 0.05). These results suggest that a small neo-sinus volume may reduce flow stagnation and particle residence, potentially reducing the risk of leaflet thrombosis. We propose that leaflet design features might be proactively controlled in the design of future transcatheter aortic valves.

Anticoagulation Therapy After Transcatheter Aortic Valve Replacement

PURPOSE OF REVIEW

We review the prevalence; natural history; impact of subclinical clinical thrombosis on valve hemodynamics, clinical outcomes, and valve durability; and the role of anticoagulation after transcatheter aortic valve replacement (TAVR).

RECENT FINDINGS

Subclinical leaflet thrombosis is a dynamic finding present in both transcatheter and surgical bioprosthetic aortic valves. This finding is less prevalent in patients on anticoagulation and resolves following initiation of anticoagulation. Routine anticoagulation after TAVR in high-surgical-risk patients was associated with increased mortality and thromboembolic complications. In the absence of a clinical indication for anticoagulation, there is no reason to initiate anticoagulation after TAVR for the prevention of subclinical leaflet thrombosis. In patients with an established indication for anticoagulation, for instance, atrial fibrillation, clinical or symptomatic valve thrombosis, or a clinical event related to valve thrombosis, anticoagulation should be initiated or continued after TAVR to treat the clinical indication.

Transcatheter aortic valve replacement: potential use in lower-risk aortic stenosis

INTRODUCTION

The widespread use of transcatheter aortic valve implantation (TAVI) is expanding to low-risk patients. Nevertheless, a low clinical risk does not always correspond to a low procedural risk for the percutaneous approach.

AREAS COVERED

The initial trials on TAVI in low-risk populations had encouraging results, showing non-inferiority in comparison to surgical aortic valve replacement (SAVR). However, the low-risk definition is based on risk score calculators developed for the surgical setting and not including other specific features that are more relevant to TAVI and can affect procedural outcomes. For example, the presence of bicuspid aortic valves, high calcific burden, low coronary height or conduction disturbances is all potentially associated with suboptimal results or even procedural complications. In addition, the lack of longer follow-up prevents us to draw conclusions about long-term outcomes, including data about valve durability and coronary re-access.

EXPERT OPINION

Although current evidence suggest similar results for TAVI and SAVR in low-risk populations, there are some technical and procedural limitations that still need to be addressed in order to close the gap between TAVI and surgery. Optimal, lasting results with a low rate of procedural complications are highly expected in low-risk, otherwise healthy subjects, with potential for longevity.

Influence of Patient-Specific Characteristics on Transcatheter Heart Valve Neo-Sinus Flow: An In Silico Study

Thrombosis in post-transcatheter aortic valve replacement (TAVR) patients has been correlated with flow stasis in the neo-sinus. This study investigated the effect of the post-TAVR geometry on flow stasis. Computed tomography angiography of 155 patients who underwent TAVR using a SAPIEN 3 were used to identify patients with and without thrombosis, and quantify thrombus volumes. Six patients with 23-mm SAPIEN 3 valves were then selected from the cohort and used to create patient-specific post-TAVR computational fluid dynamic models. Regions of flow stasis (%Vol_stasis, velocities below 0.05 m/s) were identified. The results showed that all post-TAVR anatomical measurements were significantly different in patients with and without thrombus, but only sinus diameter had a linear correlation with thrombus volume (r = 0.471, p = 0.008). A linear correlation was observed between %Vol_stasis and thrombus volume (r = 0.821, p = 0.007). The combination of anatomy and valve deployment created a unique geometry in each patient, which when combined with patient-specific cardiac output, resulted in distinct flow patterns. While parametric studies have shown individual anatomical or deployment metrics may relate to flow stasis, the combined effects of these metrics potentially contributes to the biomechanical environment promoting thrombosis, therefore hemodynamic studies of TAVR should account for these patient-specific factors.

Meta-analysis of Incidence, Predictors and Consequences of Clinical and Subclinical Bioprosthetic Leaflet Thrombosis After Transcatheter Aortic Valve Implantation

Leaflet thrombosis (LT) has been claimed as a potential cause of hemodynamic dysfunction or bioprosthetic valve degeneration of transcatheter heart valves. Sparse and contrasting evidence exists, however, regarding LT occurrence, prevention and treatment. MEDLINE, ISI Web of Science and SCOPUS databases were searched for studies published up to January 2020. Only studies reporting data on incidence and outcomes associated to the presence/absence of clinical or subclinical LT, detected or confirmed with a multidetector computed tomography exam were included. The study was designed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) requirements. Two reviewers independently screened articles for fulfillment of inclusion criteria. Data were pooled using a random-effect model. The primary end point was the incidence of LT. Secondary outcomes included: stroke and transient ischemic attacks and mean transvalvular gradients at different time-points in patients with and without LT. Of the initial 200 studies, 22 were finally included with a total of 11,567 patients. LT overall incidence was 8% (95% Confidence Interval [CI]: 5% to 13%, I² = 96.4%). LT incidence in patients receiving only antiplatelets was 13% (95% CI: 7% to 23%, p <0.0001); patients discharged on oral anticoagulants had a reported incidence of 4% (95% CI: 2% to 8%, p <0.0001). Patients with LT, either clinical or subclinical, were not at increased risk of stroke (OR 1.06, 95% CI: 0.75 to 1.50, p = 0.730, I² = 0.0%) or transient ischemic attacks (Odds Ratio 1.01, 95% CI: 0.40 to 2.57, p = 0.989, I² = 0.0%). LT was associated with higher mean transvalvular gradients compared with patients without LT at 30 days post-transcatheter implantation, but not at discharge or at 1 year. LT is a relatively common event that, even when clinically manifest, is not associated with an increased risk of cerebrovascular events. Although patients on anticoagulants appear to be at lower risk of LT, the available evidence does not allow formulation of recommendations for prophylactical anticoagulation nor routine computed tomography after transcatheter aortic valve replacement.

Subclinical Structural Valve Degeneration in Young Patients With Bioprosthetic Aortic Valves

BACKGROUND

Bioprosthetic structural valve degeneration (SVD) has previously been a clinical diagnosis, but subclinical changes have been increasingly recognized in transcatheter valves. The significance of subclinical SVD after surgical aortic valve replacement (SAVR), however, is not well understood. The purpose of this study was to characterize the incidence and outcomes of subclinical SVD in young patients after SAVR.

METHODS

Patients aged ≤65 years who underwent bioprosthetic SAVR between January 2002 and June 2018 at a single institution were included. Endocarditis cases and those with in-hospital mortality were excluded. All available longitudinal postoperative echocardiograms were reviewed. Subclinical SVD was defined as an increase in mean transvalvular gradient of at least 10 mm Hg and/or new onset of mild intraprosthetic regurgitation or increase by at least 1 grade, compared with baseline postoperative echocardiogram.

RESULTS

Overall, 822 unique SAVR cases were included. Over the study period, 356 (43.3%) patients developed subclinical SVD. Only 21.5% of those with subclinical SVD progressed to clinical SVD or to repeat aortic valve procedures. In those with progression, the first signs of SVD occurred significantly earlier than in those whose changes remained stable (11 months vs 23 months; P = .036). Anticoagulation did not impact the development or progression of subclinical SVD. There was no difference in long-term survival for those who did or did not develop subclinical SVD.

CONCLUSIONS

Subclinical SVD occurred in a large proportion of young patients undergoing bioprosthetic SAVR. Despite its high prevalence, subclinical SVD was not associated with decreased survival or repeat procedures.

Bioprosthetic valve thrombosis and degeneration following transcatheter aortic valve implantation (TAVI)

Bioprosthetic valve thrombosis (BPVT) is a recognised complication of prosthetic aortic valves and can be found in up to 13% of patients after transcatheter implantation. The mechanism of BPVT is not well known, abnormal flow conditions in the new and native sinuses and lack of functional endothelialisation are suspected causes. BPVT may result in valve dysfunction, possibly related to degeneration, and recurrence of patient symptoms, or remain subclinical. BPVT is best diagnosed at multiphase gated computed tomography (CT) angiography as the presence of reduced leaflet motion (RELM) and hypoattenuating aortic leaflet thickening (HALT). Although CT is used to exclude BPVT in symptomatic patients and those with increased valve gradients, the value of screening and prophylactic anticoagulation is debatable.

Considerations for Optimal Device Selection in Transcatheter Aortic Valve Replacement: A Review

Importance

Aortic valve stenosis (AS) is the most common manifestation of acquired valvular heart disease in developed countries. Several large-scale randomized clinical trials investigating the entire spectrum of patients with severe symptomatic AS from low to prohibitive risk have established transcatheter aortic valve replacement (TAVR) as a safe and effective alternative to surgical aortic valve replacement.

Observations

There are currently only 3 types of TAVR devices commercially available in the US, but several other valve types are undergoing clinical trials in the US. Because of fundamental differences in engineering features, each TAVR device type has specific strengths and limitations. This review aims to provide an overview of design features and clinical outcomes of various TAVR devices that are either commercially available or undergoing clinical investigation.

Conclusions and Relevance

Given the lack of large-scale head-to-head comparisons of various TAVR devices and the rapid development of new device iterations, there is insufficient evidence to claim superiority of one device type over another. Nonetheless, as each TAVR device has unique design characteristics, certain patient-related and anatomy-related factors may slightly favor one or several particular designs.

Bioprosthetic aortic valve haemodynamic deterioration secondary to a thrombus

A 77-year-old man with a history of coronary artery bypass grafting and surgical aortic valve replacement for severe aortic stenosis 2 years prior presented with exertional chest pain and shortness of breath. The patient underwent a thorough initial evaluation including a transthoracic echocardiogram and coronary angiogram without significant findings. One month later the patient presented with worsened symptoms and a repeat echocardiogram showed an increased mean aortic valve gradient of 87 mm Hg. The patient had to undergo reoperation for a surgical aortic valve replacement and was found to have an aortic bioprosthetic valve thrombus. This case suggests a mismatch between the aortic prosthesis and the patient's aortic root size.

Self-expanding intra-annular versus commercially available transcatheter heart valves in high and extreme risk patients with severe aortic stenosis (PORTICO IDE): a randomised, controlled, non-inferiority trial

BACKGROUND

Randomised trial data assessing the safety and efficacy of the self-expanding intra-annular Portico transcatheter aortic valve system (Abbott Structural Heart, St Paul, MN, USA) compared with any commercially available valves are needed to compare performance among designs.

METHODS

In this prospective, multicentre, non-inferiority, randomised controlled trial (the Portico Re-sheathable Transcatheter Aortic Valve System US Investigational Device Exemption trial [PORTICO IDE]), high and extreme risk patients with severe symptomatic aortic stenosis were recruited from 52 medical centres experienced in performing transcatheter aortic valve replacement in the USA and Australia. Patients were eligible if they were aged 21 years or older, in New York Heart Association functional class II or higher, and had severe native aortic stenosis. Eligible patients were randomly assigned (1:1) using permuted block randomisation (block sizes of 2 and 4) and stratified by clinical investigational site, surgical risk cohort, and vascular access method, to transcatheter aortic valve replacement with the first generation Portico valve and delivery system or a commercially available valve (either an intra-annular balloon-expandable Edwards-SAPIEN, SAPIEN XT, or SAPIEN 3 valve [Edwards LifeSciences, Irvine, CA, USA]; or a supra-annular self-expanding CoreValve, Evolut-R, or Evolut-PRO valve [Medtronic, Minneapolis, MN, USA]). Investigational site staff, implanting physician, and study participant were unmasked to treatment assignment. Core laboratories and clinical event assessors were masked to treatment allocation. The primary safety endpoint was a composite of all-cause mortality, disabling stroke, life-threatening bleeding requiring transfusion, acute kidney injury requiring dialysis, or major vascular complication at 30 days. The primary efficacy endpoint was all-cause mortality or disabling stroke at 1 year. Clinical outcomes and valve performance were assessed up to 2 years after the procedure. Primary analyses were by intention to treat and the Kaplan-Meier method to estimate event rates. The non-inferiority margin was 8·5% for primary safety and 8·0% for primary efficacy endpoints. This study is registered with ClinicalTrials.gov, NCT02000115, and is ongoing.

FINDINGS

Between May 30 and Sept 12, 2014, and between Aug 21, 2015, and Oct 10, 2017, with recruitment paused for 11 months by the funder, we recruited 1034 patients, of whom 750 were eligible and randomly assigned to the Portico valve group (n=381) or commercially available valve group (n=369). Mean age was 83 years (SD 7) and 395 (52·7%) patients were female. For the primary safety endpoint at 30 days, the event rate was higher in the Portico valve group than in the commercial valve group (52 [13·8%] vs 35 [9·6%]; absolute difference 4·2, 95% CI -0·4 to 8·8 [upper confidence bound {UCB} 8·1%]; p_{non-inferiority}=0·034, p_superiority=0·071). At 1 year, the rates of the primary efficacy endpoint were similar between the groups (55 [14·8%] in the Portico group vs 48 [13·4%] in the commercial valve group; difference 1·5%, 95% CI -3·6 to 6·5 [UCB 5·7%]; p_{non-inferiority}=0·0058, p_superiority=0·50). At 2 years, rates of death (80 [22·3%] vs 70 [20·2%]; p=0·40) or disabling stroke (10 [3·1%] vs 16 [5·0%]; p=0·23) were similar between groups.

INTERPRETATION

The Portico valve was associated with similar rates of death or disabling stroke at 2 years compared with commercial valves, but was associated with higher rates of the primary composite safety endpoint including death at 30 days. The first-generation Portico valve and delivery system did not offer advantages over other commercially available valves.

FUNDING

Abbott.

The role of four-dimensional computed tomography in transcatheter aortic valve replacement prosthesis endocarditis with concurrent leaflet thrombosis: a case report

Background

Transcatheter aortic valve replacement (TAVR) is becoming increasingly utilized for the treatment of severe aortic valvular heart disease. Infective endocarditis of TAVR is rare but associated with higher mortality and morbidity. The potential for leaflet thrombosis following TAVR is also becoming increasingly recognized. Diagnosis of these conditions on echocardiography can be challenging due to prosthesis artefact.

Case summary

An 84-year-old man with a previous transcatheter aortic valve replacement presented with a febrile illness and bacteraemia. Transthoracic and transoesophageal echocardiography demonstrated high transvalvular gradients with features of prosthesis endocarditis, though leaflet morphology could not be fully assessed due to prosthesis artefact. Four-dimensional computed tomography revealed hypo-attenuated leaflet thickening with reduced leaflet motion, consistent with prosthesis leaflet thrombosis. The patient was successfully treated with antibiotics and anticoagulation, with resolution of the infection and normalization of the transvalvular gradient after 6 weeks.

Discussion

Echocardiography should be the first-line investigation for assessing leaflet morphology in suspected prosthetic valve endocarditis or leaflet thrombosis but its accuracy may be limited by artefact. Our case highlights that four-dimensional computed tomography provides further evaluation of prosthesis leaflet morphology/motion, providing valuable diagnostic information.