Incidence, Predictors, and Mid-Term Outcomes of Possible Leaflet Thrombosis After TAVR

Subclinical valve leaflet thrombosis following bioprosthetic aortic valve replacement

PURPOSE OF REVIEW

Subclinical leaflet thrombosis (SLT) is often an incidental finding characterized by a thin layer of thrombus involving one, two or three leaflets, with typical appearance on multi-detector computed tomography (MDCT) of hypo-attenuating defect at the aortic side of the leaflet, also called hypo-attenuating leaflet thickening (HALT). SLT may occur following both transcatheter aortic replacement (TAVR) or biological surgical aortic valve replacement (SAVR). The aim of this review is to present an overview of the current state of knowledge on the incidence, diagnosis, clinical impact, and management of SLT following TAVR or SAVR.

RECENT FINDINGS

SLT occurs in 10-20% of patients following TAVR and is somewhat more frequent than following SAVR (5-15%). SLT may regress spontaneously without treatment in about 50% of the cases but may also progress to clinically significant valve thrombosis in some cases. Oral anticoagulation with vitamin K antagonist is reasonable if SLT is detected by echocardiography and/or MDCT during follow-up and is generally efficient to reverse SLT. SLT is associated with mild increase in the risk of stroke but has no impact on survival. SLT has been linked with accelerated structural valve deterioration and may thus impact valve durability and long-term outcomes.

SUMMARY

SLT is often an incidental finding on echocardiography or MDCT that occurs in 10-20% of patients following TAVR or 5-15% following biological SAVR and is associated with a mild increase in the risk of thrombo-embolic event with no significant impact on mortality but may be associated with reduced valve durability.

Treatment of Transcatheter Aortic Valve Thrombosis: JACC Review Topic of the Week

Transcatheter aortic valve (TAV) thrombosis may manifest as subclinical leaflet thrombosis (SLT) and clinical valve thrombosis. SLT is relatively common (10%-20%) after transcatheter aortic valve replacement, but clinical implications are uncertain. Clinical valve thrombosis is rare (1.2%) and associated with bioprosthetic valve failure, neurologic or thromboembolic events, heart failure, and death. Treatment for TAV thrombosis has been understudied. In principle, anticoagulation may prevent TAV thrombosis. Non-vitamin K oral anticoagulants, as compared to antiplatelet therapy, are associated with reduced incidence of SLT, although at the cost of higher bleeding and all-cause mortality risk. We present an overview of existing literature for management of TAV thrombosis and propose a rational treatment algorithm. Vitamin K antagonists or non-vitamin K oral anticoagulants are the cornerstone of antithrombotic treatment. In therapy-resistant or clinically unstable patients, ultraslow, low-dose infusion of thrombolytics seems effective and safe and may be preferred over redo-transcatheter aortic valve replacement or explant surgery.

Prediction model for leaflet thrombosis in patients undergoing transcatheter aortic valve implantation: the EFFORT study

BACKGROUND

Leaflet thrombosis (LT) is a multifaceted and underexplored condition that can manifest following transcatheter aortic valve implantation (TAVI). The objective of this study was to formulate a prediction model based on laboratory assessments and clinical parameters, providing additional guidance and insight into this relatively unexplored aspect of post-TAVI complications.

METHODS

The present study was an observational prospective hypothesis-generating study, including 101 patients who underwent TAVI and a screening for LT (the primary endpoint) by multidetector computed tomography (MDCT). All images were acquired on a third-generation dual-source CT system. Levels of von Willebrand factor (vWF) activity, hemoglobin (Hb), and lactate dehydrogenase (LDH) were measured among other parameters. A predictive score utilizing binary logistic regression, Kaplan-Meier time-to-event analysis, and receiver operating characteristics (ROC) analysis was established.

RESULTS

LT (11 subclinical and 2 clinical) was detected in 13 of 101 patients (13%) after a median time to screening by MDCT of 105 days (IQR, 98-129 days). Elevated levels of vWF activity (> 188%) pre-TAVI, decreased Hb values (< 11.9 g/dL), as well as increased levels of LDH (> 312 U/L) post-TAVI and absence of oral anticoagulation (OAC) were found in patients with subsequent LT formation as compared to patients without LT. The established EFFORT score ranged from - 1 to 3 points, with an increased probability for LT development in patients with ≥ 2 points (85.7% of LT cases) vs < 2 points (14.3% of LT cases; p < 0.001). Achieving an EFFORT score of ≥ 2 points was found to be significantly associated with a 10.8 times higher likelihood of developing an LT (p = 0.001). The EFFORT score has an excellent c-statistic (area under the curve (AUC) = 0.89; 95% CI 0.74-1.00; p = 0.001) and a high negative predictive value (98%).

CONCLUSION

An EFFORT score might be a helpful tool to predict LT development and could be used in risk assessment, if validated in confirmatory studies. Therefore, the score has the potential to guide the stratification of individuals for the planning of subsequent MDCT screenings.

Subclinical leaflet thrombosis and anticoagulation strategy following trans-catheter aortic valve replacement: A systematic review

Objective

Subclinical leaflet thrombosis (SLT) develops in 15% of patients undergoing trans-catheter aortic valve replacement (TAVR). TAVR is a procedure in which a faulty aortic valve is replaced with a mechanical one. An aortic valve replacement can be done with open-heart surgery; this is called surgical aortic valve replacement (SAVR). A significant problem is defining the best course of treatment for asymptomatic individuals with SLT post-TAVR, including the use of oral anticoagulation (OAC) in it.

Study design

Systematic review.

Method

The most pertinent published research (original papers and reviews) in the scientific literature were searched for and critically assessed using the online, internationally indexed databases PubMed, Medline, and Cochrane Reviews. Keywords like "Transcatheter valve replacement" and "Subclinical leaflet thrombosis" were used to search the papers. Selected studies were critically assessed for inclusion based on predefined criteria.

Results

The review examined the prevalence and characteristics of SLT after TAVR. To note, the incidence of SLT is seen to be higher in TAVR compared SAVR. Dual antiplatelet therapy, which is utilized in antithrombotic regimens post-TAVR, can possibly hasten SLT progression which could result in the impaired mobility of leaflets and the worsening of pressure gradients.

Conclusion

The use of dual antiplatelet drugs in routine antithrombotic therapy tends to accelerate initial subclinical leaflet thrombosis after TAVI, which results in a developing restriction of leaflet mobility and an increase in pressure differences.

Pretranscatheter and Posttranscatheter Valve Planning with Computed Tomography

The range of potential transcatheter solutions to valve disease is increasing, bringing treatment options to those in whom surgery confers prohibitively high risk. As the range of devices and their indications grow, so too will the demand for procedural planning. Computed tomography will continue to enable this growth through the provision of accurate device sizing and procedural risk assessment.

Pharmacologic targeting of coagulation factors XII and XI by monoclonal antibodies reduces thrombosis in nitinol stents under flow

BACKGROUND

Cardiovascular implantable devices, such as vascular stents, are critical for the treatment of cardiovascular diseases. However, their success is dependent on robust and often long-term antithrombotic therapies. Yet, the current standard-of-care therapies often pose significant bleeding risks to patients. Coagulation factor (F)XI and FXII have emerged as potentially safe and efficacious targets to safely reduce pathologic thrombin generation in medical devices.

OBJECTIVES

To study the efficacy of monoclonal antibody-targeting FXII and FXI of the contact pathway in preventing vascular device-related thrombosis.

METHODS

The effects of inhibition of FXII and FXI using function-blocking monoclonal antibodies were examined in a nonhuman primate model of nitinol stent-related thrombosis under arterial and venous flow conditions.

RESULTS

We found that function-blocking antibodies of FXII and FXI reduced markers of stent-induced thrombosis in vitro and ex vivo. However, FXI inhibition resulted in more effective mitigation of thrombosis markers under varied flow conditions.

CONCLUSION

This work provides further support for the translation of contact pathway of coagulation inhibitors for their adjunctive clinical use with cardiovascular devices.

Antithrombotic Treatment After Transcatheter Valve Interventions: Current Status and Future Directions

PURPOSE

The optimal antithrombotic strategy after transcatheter valve interventions is a subject of ongoing debate. Although there is evidence from randomized trials in patients undergoing transcatheter aortic valve replacement (TAVR), current evidence on optimal antithrombotic management after transcatheter mitral or tricuspid valve interventions is sparse. This article appraises the current evidence on this topic.

METHODS

This narrative review presents key research findings and guideline recommendations, as well as highlights areas for future research.

FINDINGS

After TAVR, randomized trial evidence suggests that single antiplatelet therapy is reasonable for patients without pre-existing indications for oral anticoagulation (OAC). If there is a concurrent indication for OAC, the addition of antiplatelet therapy increases bleeding risk. Whether direct oral anticoagulants achieve better outcomes than vitamin K antagonists is uncertain in this setting. Although OAC has been shown to reduce subclinical leaflet thrombosis (which may progress to structural valve degeneration), bleeding events are unacceptably high. There is a lack of randomized trial data comparing antithrombotic strategies after transcatheter mitral or tricuspid valve replacement or after mitral or tricuspid transcatheter edge-to-edge repair. Single antiplatelet therapy after mitral or tricuspid transcatheter edge-to-edge repair may be appropriate, whereas at least 3 months of OAC is suggested after transcatheter mitral valve replacement or transcatheter tricuspid valve replacement.

IMPLICATIONS

Randomized studies are warranted to address the knowledge gaps in antithrombotic therapy after transcatheter valve interventions and to optimize outcomes.

Frequency, Predictors, and Clinical Impact of Valvular and Perivalvular Thrombus After Transcatheter Aortic Valve Replacement

BACKGROUND

Subclinical aortic valve complex (valvular and perivalvular) thrombus is not rare after transcatheter aortic valve replacement (TAVR). The risk factors and clinical implications of these findings remain uncertain.

OBJECTIVES

This study sought to evaluate the frequency, predictors, and clinical outcome of aortic valve complex thrombus after TAVR.

METHODS

In the ADAPT-TAVR (Anticoagulation Versus Dual Antiplatelet Therapy for Prevention of Leaflet Thrombosis and Cerebral Embolization After Transcatheter Aortic Valve Replacement) trial comparing edoxaban vs dual antiplatelet therapy in TAVR patients without an indication for chronic anticoagulation, the frequency of valvular (subclinical leaflet thrombus) and perivalvular (supravalvular, subvalvular, and sinus of Valsalva) thrombus was evaluated by 4-dimensional computed tomography at 6 months. The association of these phenomena with new cerebral thromboembolism on brain magnetic resonance imaging, neurologic and neurocognitive dysfunction, and clinical outcomes was assessed.

RESULTS

Among 211 patients with 6-month computed tomography evaluations, 91 patients (43.1%) had thrombus at any aortic valve complex, 30 (14.2%) patients had leaflet thrombus, and 78 (37.0%) patients had perivalvular thrombus. A small maximum diameter of the stent at the valve level and low body surface area were independent predictors of aortic valve complex and perivalvular thrombus, and decreased renal function was an independent predictor of leaflet thrombus. No significant differences were observed in new cerebral lesions, neurologic or neurocognitive functions, or clinical outcomes among patients with or without valvular or perivalvular thrombus.

CONCLUSIONS

Subclinical aortic valve complex (valvular and perivalvular) thrombus was common in patients who had undergone successful TAVR. However, these imaging phenomena were not associated with new cerebral thromboembolism, neurologic or neurocognitive dysfunction, or adverse clinical outcomes. (Anticoagulation Versus Dual Antiplatelet Therapy for Prevention of Leaflet Thrombosis and Cerebral Embolization After Transcatheter Aortic Valve Replacement [ADAPT-TAVR]; NCT03284827).

Altered blood flow due to larger aortic diameters in patients with transcatheter heart valve thrombosis

The etiology of transcatheter heart valve thrombosis (THVT) and the relevance of the aortic root geometry on the occurrence of THVT are largely unknown. The first aim of this pilot study is to identify differences in aortic root geometry between THVT patients and patients without THVT after transcatheter aortic valve implantation (TAVI). Second, we aim to investigate how the observed difference in aortic diameters affects the aortic flow using idealized computational geometric models. Aortic dimension was assessed using pre-TAVI multi-detector computed tomography scans of eight patients with clinical apparent THVT and 16 unaffected patients (two for each THVT patient with same valve type and size) from the Bern-TAVI registry. Among patients with THVT the right coronary artery height was lower (-40%), and sinotubular junction (STJ) and ascending aorta (AAo) diameters tended to be larger (9% and 14%, respectively) compared to the unaffected patients. Fluid-structure interaction (FSI) in two idealized aortic models with the observed differences in STJ and AAo diameter showed higher backflow rate at the STJ (+16%), lower velocity magnitudes in the sinus (-5%), and higher systolic turbulent dissipation rate in the AAo (+8%) in the model with larger STJ and AAo diameters. This pilot study suggests a direct effect of the aortic dimensions on clinically apparent THVT. The FSI study indicates that larger STJ and AAo diameters potentially favor thrombus formation by increased backflow rate and reduced wash-out efficiency of the sinus. The reported observations require clinical validation but could potentially help identifying patients at risk for THVT.

Bioprosthetic leaflet thrombosis and reduced leaflet motion after transcatheter aortic valve replacement: A systematic review and meta-analysis

BACKGROUND

Leaflet thrombosis and reduced leaflet motion have become a concern with the expanding use of transcatheter aortic valve replacement in lower-risk patients.

AIMS

To assess the proportions, predictors and clinical impact of leaflet thrombosis and reduced leaflet motion after transcatheter aortic valve replacement.

METHODS

We performed a meta-analysis of studies assessing the proportions of and/or clinical outcomes according to the presence of leaflet thrombosis after transcatheter aortic valve replacement identified with computed tomography and/or echocardiography.

RESULTS

Fifty-three studies, representing 25,258 patients undergoing transcatheter aortic valve replacement, were considered. The proportion of leaflet thrombosis was 5.2% overall, and was higher in computed tomography versus echocardiography (16.4% vs. 1.1%, respectively); reduced leaflet motion was identified in 11% of patients with four-dimensional computed tomography. Intra-annular bioprostheses were associated with a higher proportion of leaflet thrombosis, whereas chronic oral anticoagulation was protective for leaflet thrombosis in both computed tomography and echocardiographic studies (9.7% vs. 17.5%; relative risk [RR]: 0.51, 95% confidence interval [95% CI]: 0.37-0.71 and 0.9% vs. 2.7%; RR: 0.22, 95% CI: 0.06-0.79, respectively) and for reduced leaflet motion (2.5% vs. 12.4%; RR: 0.32, 95% CI: 0.13-0.76). Leaflet thrombosis was not associated with an increased risk of death, but with a higher risk of stroke in computed tomography studies (2.8% vs. 2.4%; RR: 1.63, 95% CI: 1.05-2.55), a difference more pronounced when considering reduced leaflet motion (3.5% vs. 1.7%; RR: 2.39, 95% CI: 0.63-8.34).

CONCLUSIONS

The proportion of leaflet thrombosis is highly variable according to the screening approach, the type of valve and the use of oral anticoagulation. The occurrence of cerebral events is increased when leaflet thrombosis and/or reduced leaflet motion are diagnosed, but leaflet thrombosis has no impact on survival.

Early 6 months usage of single anTiplAtelet OR anTicoAgulant followed by single antiplatelet after transcatheter aortic valve replacement: protocol for a multicentre, open-label, randomised controlled clinical trial

INTRODUCTION

The strategy for initiating antithrombotic therapy to prevent bioprosthetic valve thrombosis (BPVT) after transcatheter aortic valve replacement (TAVR) remains uncertain. There is still lacking evidence on the efficacy and safety of early 6 months usage of single-antiplatelet therapy (SAPT) or oral anticoagulant (OAC) after TAVR in patients without anticoagulant indications.

METHODS AND ANALYSIS

This is a multicentre, randomised controlled, open-label trial, and 650 patients undergoing TAVR from 13 top TAVR centres in China will be recruited. Each eligible participant will be randomly assigned to two groups (1:1 ratio) as (1) SAPT (aspirin 75-100 mg for 6 months) group or (2) OAC group (warfarin, therapeutic international normalised ratio at 1.8-2.5 for 6 months), both followed by sequential aspirin 75-100 mg for 6 months. Participants in both groups will be invited for three follow-up visits of 1, 6 and 12 months after discharge. We will use both the net clinical benefit endpoint (composite of all-cause mortality, myocardial infarction, stroke/transient ischaemic attacks, peripheral artery thrombosis, intracardiac thrombosis and major bleeding and disabling or life-threatening bleeding) and the BPVT endpoint evaluated by four-dimensional CT as our primary endpoints. P value of <0.05 of two-sided test will be considered statistically significant.

ETHICS AND DISSEMINATION

The present study was approved by the Institutional Review Boards at Fuwai Hospital, National Center for Cardiovascular Diseases of China (Approval No. 2023-1947). All patients will be informed of the details of the study and will sign an informed consent prior to inclusion in the study. Results of this study will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT05375474.

Leaflet thrombosis in transcatheter aortic valve intervention: mechanisms, prevention, and treatment options

Introduction

Transcatheter aortic valve intervention (TAVR) has emerged as a promising alternative to surgical aortic valve replacement for patients with severe aortic stenosis. However, leaflet thrombosis has raised concerns about the long-term durability and outcomes of TAVR. This study aims to provide an overview of the mechanisms, prevention strategies, and treatment options for leaflet thrombosis in TAVR.

Clinical evidence

Leaflet thrombosis refers to the formation of blood clots on bioprosthetic valve leaflets, leading to impaired leaflet mobility, early valve degeneration and dysfunction, and potential clinical implications. While the mechanisms underlying thrombus formation on valve leaflets are not fully understood, several factors, such as altered blood flow patterns within valve neosinuses, prothrombotic surfaces, and patient-related causes, have been implicated. Two distinct entities have been identified, namely, hypoattenuated leaflet thickening and restricted leaflet motion. Their occurrence appears dynamic over time and is related to the valve type. Imaging, including transesophageal echocardiography and multidetector computed tomography, plays a crucial role in the diagnosis and follow-up of leaflet thrombosis.

Prevention and treatment options

Preventing leaflet thrombosis requires a comprehensive and tailored approach involving identifying high-risk patients, close monitoring, and antithrombotic therapy. Antithrombotic therapy with dual antiplatelet agents or anticoagulation is commonly employed in TAVR patients, although the optimal regimen is yet to be defined. Novel antithrombotic agents, such as direct oral anticoagulants, are being investigated for their efficacy and safety in preventing leaflet thrombosis. When leaflet thrombosis is detected, treatment options include intensified antithrombotic therapy, valve-in-valve intervention, or balloon valvuloplasty. The long-term outcomes and impact of leaflet thrombosis on valve durability and patient prognosis are areas of ongoing research.

Summary

Leaflet thrombosis in TAVR is a considerable complication affecting valve function and patient outcomes. Understanding the mechanisms underlying thrombus formation and implementing appropriate prevention strategies are essential for mitigating this risk. Treatment options aim to restore leaflet mobility and optimize valve performance. Further research is needed to establish standardized protocols for antithrombotic therapy, identify high-risk patient populations, and determine the long-term consequences of leaflet thrombosis on TAVR outcomes.

Antithrombotic therapy with Transcatheter aortic valve replacement

Aortic valve replacement is a necessary management strategy for patients with severe aortic stenosis. The use of transaortic valve replacement (TAVR) has increased significantly over the last decade and now exceeds traditional surgical aortic valve replacement. Since the valve systems used in TAVR consist of bioprosthetic valve tissue encased in a metal stent frame, antithrombotic therapy recommendations cannot be extrapolated from prior data with differently constructed surgical bioprosthetic or mechanical valves. Data on the use of antithrombotic therapy with TAVR are a rapidly developing area of medicine. Choice of agents depends on several patient factors. Patients undergoing TAVR also have a relatively high incidence of subclinical valve thrombosis. The clinical impact of this phenomenon and the implications for antithrombotic therapy continue to evolve. It is critical for clinicians who treat patients undergoing TAVR to have a firm understanding of practice guidelines, the evolving evidence, and its implications for the use of antithrombotic therapy in these patients.

Effect of Edoxaban Versus Antiplatelet Therapy on Leaflet Thrombosis and Cerebral Thromboembolism After TAVI According to Major Clinical and Anatomic Factors in Prespecified Subgroup Analysis from the ADAPT-TAVR Trial

It is unknown whether edoxaban versus dual antiplatelet therapy (DAPT) has differential treatment effects on leaflet thrombosis, cerebral thromboembolism, and neurologic or neurocognitive dysfunction according to clinical and anatomic factors after transcatheter aortic valve implantation. To investigate the relative effects of edoxaban and DAPT on leaflet and cerebral thromboembolism in patients with major risk factors. The primary end point of this study was the incidence of leaflet thrombosis on computed tomography at 6 months. The secondary end points were new cerebral lesions on brain magnetic resonance imaging and neurologic and neurocognitive dysfunction between baseline and 6-month follow-up. Cox regression models assessed the consistency of the treatment effects in the prespecified subgroups. The favorable effect of edoxaban versus DAPT on the leaflet thrombosis was consistent across multiple clinical or anatomic subgroups, without significant interaction between the drug effect and each subgroup (p for interaction for age = 0.597, gender = 0.557, body mass index = 0.866, Society of Thoracic Surgeons score = 0.307, valve type = 0.702, edoxaban reduction criteria = 0.604, and valve morphology = 0.688). However, the incidence of new cerebral lesions on brain magnetic resonance imaging and worsening of neurologic and neurocognitive function were not significantly different between the groups among the various key subgroups. The relative effects of edoxaban and DAPT on the risk of leaflet thrombosis, cerebral thromboembolism, and neurologic dysfunction were consistent across a diverse spectrum of clinical or anatomical factors. Further studies are required to define tailored antithrombotic therapy for high-risk groups with specific clinical or anatomic characteristics.

Comparison of oral anticoagulation by vitamin-K antagonists and non-vitamin-K antagonists for treatment of leaflet thickening after transcatheter aortic valve implantation (TAVI)

INTRODUCTION

Hypoattenuated leaflet thickening (HALT), as identified by CT imaging, is not infrequent after transcatheter aortic valve implantation (TAVI). The best choice of oral anticoagulation is unknown. We compared the effectiveness of Direct Oral AntiCoagulants (DOAC) and Vitamin-K Antagonists (VKA) to resolve HALT in patients with serial CT aquisitions.

METHODS

A total of 46 consecutive TAVI patients in whom anticoagulation had been initiated because of HALT and who underwent follow-up CT were identified. Indication and type of anticoagulation was according to physician discretion. Patients on DOAC were compared to VKA therapy regarding resolution of HALT.

RESULTS

Mean age of the 46 patients was 80 ± 6 years (59% men), and the mean duration of anticoagulation was 156 days. Overall, 41 patients (89%) showed resolution of HALT with anticoagulation therapy, whereas HALT persisted in 5 patients (11%). Resolution of HALT was seen in 26 out of 30 (87%) patients receiving VKA and in 15 out of 16 (94%) patients receiving DOAC, respectively. Groups did not differ regarding age, cardiovascular risk factors, TAVI prosthesis type and size or duration of anticoagulation (all p > 0.05).

CONCLUSION

Anticoagulation therapy resolves leaflet thickening after TAVI in most patients. Non-Vitamin-K antagonists seem to be an effective alternative to Vitamin-K antagonists. This finding needs to be confirmed in larger prospective trials.

A Contemporary Review of Antiplatelet Therapies in Current Clinical Practice

Antiplatelet therapy plays a crucial role in a number of cardiovascular disorders. We currently have a range of antiplatelet agents in our armamentarium. In this review, we aim to summarise the common antiplatelet agents currently available, and their use in clinic practice. We not only highlight recent trials exploring antiplatelet therapy in atherosclerotic cardiovascular disease, but also in trials related to transcatheter aortic valve implantation and coronavirus disease 2019. Inevitably, the antithrombotic benefits of these drugs are accompanied by an increase in bleeding complications. Therefore, an individualised approach to weighing each patient's thrombotic risk versus bleeding risk is imperative, in order to improve clinical outcomes.

Platelet and Monocyte Activation After Transcatheter Aortic Valve Replacement (POTENT-TAVR): A Mechanistic Randomized Trial of Ticagrelor Versus Clopidogrel

Background

Inflammation and thrombosis are often linked mechanistically and are associated with adverse events after transcatheter aortic valve replacement (TAVR). High residual platelet reactivity (HRPR) is especially common when clopidogrel is used in this setting, but its relevance to immune activation is unknown. We sought to determine whether residual activity at the purinergic receptor P2Y12 (P2Y12) promotes prothrombotic immune activation in the setting of TAVR.

Methods

This was a randomized trial of 60 patients (enrolled July 2015 through December 2018) assigned to clopidogrel (300mg load, 75mg daily) or ticagrelor (180mg load, 90 mg twice daily) before and for 30 days following TAVR. Co-primary endpoints were P2Y12-dependent platelet activity (Platelet Reactivity Units; VerifyNow) and the proportion of inflammatory (cluster of differentiation [CD] 14+/CD16+) monocytes 1 day after TAVR.

Results

Compared to clopidogrel, those randomized to ticagrelor had greater platelet inhibition (median Platelet Reactivity Unit [interquartile range]: (234 [170.0-282.3] vs. 128.5 [86.5-156.5], p < 0.001), but similar inflammatory monocyte proportions (22.2% [18.0%-30.2%] vs. 25.1% [22.1%-31.0%], p = 0.201) 1 day after TAVR. Circulating monocyte-platelet aggregates, soluble CD14 levels, interleukin 6 and 8 levels, and D-dimers were also similar across treatment groups. HRPR was observed in 63% of the clopidogrel arm and was associated with higher inflammatory monocyte proportions. Major bleeding events, pacemaker placement, and mortality did not differ by treatment assignment.

Conclusions

Residual P2Y12 activity after TAVR is common in those treated with clopidogrel but ticagrelor does not significantly alter biomarkers of prothrombotic immune activation. HRPR appears to be an indicator (not a cause) of innate immune activation in this setting.

Natural History of Leaflet Thrombosis After Transcatheter Aortic Valve Replacement: A 5-Year Follow-Up Study

Background Subclinical leaflet thrombosis, characterized by hypoattenuated leaflet thickening (HALT) on multidetector computed tomography, is common after transcatheter aortic valve replacement (TAVR). Because little is known about the long-term natural history of subclinical HALT, we aimed to investigate this in patients who underwent TAVR without using additional anticoagulation. Methods and Results We retrospectively evaluated patients who underwent TAVR with the Edwards SAPIEN-XT at our institute between October 2013 and December 2015. Patients were grouped according to the presence or absence of HALT within 1 year after TAVR (HALT and No-HALT groups). The primary outcome, defined as the composite of all-cause mortality, heart failure readmission, and ischemic stroke, was compared. Valve performance was assessed over time by transthoracic echocardiography. Among 124 patients (men: 29.1%; median age, 85 years), 27 (21.8%) showed HALT on multidetector computed tomography within 1 year after TAVR. No patient required additional anticoagulation for treating HALT because of the absence of valve-related symptomatic deterioration. During the median follow-up period of 4.7 years (interquartile range, 4.0-5.6), the rate of primary outcome and valve performance was not statistically different between the 2 groups (37.0% versus 38.1%; log-rank test P=0.92; mean pressure gradient, 9 mm Hg [8-14 mm Hg] versus 10 mm Hg [7-15 mm Hg]; P=0.51, respectively). Conclusions Approximately 20% of patients after TAVR had HALT within 1 year; however, that did not change the risk of subsequent adverse cardiovascular events or the valve performance with statistical significance for up to 5 years despite no additional anticoagulation therapy.

The search for optimal antithrombotic therapy in transcatheter aortic valve implantation: facts and uncertainties

Transcatheter aortic valve implantation (TAVI) is a minimally invasive procedure, which is used frequently in patients with symptomatic severe aortic valve stenosis. Most patients undergoing TAVI are over 80 years of age with a high bleeding as well as thrombotic risk. Despite the increasing safety of the procedure, thromboembolic events [stroke, (subclinical) valve thrombosis] remain prevalent. As a consequence, antithrombotic prophylaxis is routinely used and only recently new data on the efficacy and safety of antithrombotic drugs has become available. On the other hand, these antithrombotic drugs increase bleeding in a population with unique aortic stenosis-related bleeding characteristics (such as acquired von Willebrand factor defect and angiodysplasia). In this review, we discuss the impact of thromboembolic and bleeding events, the current optimal antithrombotic therapy based on registries and recent randomized controlled trials, as well as try to give a practical guide how to treat these high-risk patients. Finally, we discuss knowledge gaps and future research needed to fill these gaps.

Risk factors and clinical effects of subclinical leaflet thrombosis after transcatheter aortic valve replacement

Aims

The number of trans-catheter aortic valve replacement (TAVR) procedure is increasing; However, the incidence of leaflet thrombosis is higher in TAVR than in surgical aortic valve replacement (SAVR). In this study, the risk factors for leaflet thrombosis after TAVR and its effects on hemodynamics and clinical course were investigated.

Methods and results

Multidetector computed tomography (MDCT) was performed at 1year after TAVR in 94 patients from January 2015 to October 2020 at Samsung Medical Center in South Korea. Among the 94 patients, subclinical leaflet thrombosis occurred in 20 patients, and risk factors were analyzed. In addition, the difference in aortic valve (AV) hemodynamics between the two groups was examined and clinical outcomes compared. Indexed mean sinus of Valsalva (SOV) diameter, AV calcium volume, and post-procedure effective orifice area (EOA) were predictive of subclinical leaflet thrombosis with the area under the curve (AUC) value of 0.670 (P-value = 0.020), 0.695 (P-value = 0.013), and 0.665 (P-value = 0.031), respectively. In echocardiography performed at the time of follow-up CT, the value of AV max velocity and AV mean pressure gradient were higher in the thrombosis group and the EOA and Doppler velocity index values were lower in the thrombosis group than in the no thrombosis group. Clinical outcome was not significantly different between the two groups (log-rank P-value = 0.26).

Conclusion

Larger indexed SOV diameter, higher AV calcium volume, and smaller post-procedure AV EOA were risk factors for subclinical leaflet thrombosis after TAVR. Subclinical leaflet thrombosis has a benign course when properly managed.

Effect of Native Aortic Leaflet Geometry Modification on Transcatheter Aortic Valve Neo-sinus and Aortic Sinus Flow: An In-vitro Study

PURPOSE

Leaflet thrombosis is a potentially fatal complication after transcatheter aortic valve replacement (TAVR). Blood flow stagnation in the neo-sinus and aortic sinuses are associated with increased thrombus severity. Native aortic leaflet modification may be a potential strategy to improve the neo-sinus and aortic sinus fluid dynamics. However, limited data exist on the effect of leaflet geometry modification on the flow within the neo-sinus and aortic sinus regions. We evaluate the effect of aortic leaflet modification on the neo-sinus and aortic sinus flow stagnation after simulated TAVR.

METHODS

Particle image velocimetry measurements were performed under nominal (5 LPM) and low (2.5 LPM) cardiac output conditions for an intact leaflet (control) case, and 3 modified leaflet geometries. Aortic leaflet geometry modification via leaflet splay was simulated with increasing splay geometry (leaflet splay distance: 5 mm-narrow, 10 mm-medium, and 20 mm-wide).

RESULTS

Leaflet geometry modification influenced flow features throughout the cardiac cycle, at both cardiac outputs, and allowed for flow communication between the neo-sinus and aortic sinus regions compared to the control. In the aortic sinus, flow stagnation reduced by over 64% at 5LPM, and over 36% at 2.5LPM for all simulated modified leaflet geometries compared to the control. However, only the medium and wide splay geometries enabled a reduction in neo-sinus flow stagnation compared to the control case.

CONCLUSIONS

These findings suggest that aortic leaflet geometry modification (of at least 10 mm leaflet splay distance) may reduce flow stasis and potentially decrease valve thrombosis risk.

Subclinical leaflet thrombosis after transcatheter aortic valve implantation is associated with silent brain injury on brain magnetic resonance imaging

AIMS

Whether hypoattenuated leaflet thickening (HALT) following transcatheter aortic valve implantation (TAVI) carries a risk of subclinical brain injury (SBI) is unknown. We investigated whether HALT is associated with SBI detected on magnetic resonance imaging (MRI), and whether post-TAVI SBI impacts the patients' cognition and outcome.

METHODS AND RESULTS

We prospectively enrolled 153 patients (age: 78.1 ± 6.3 years; female 44%) who underwent TAVI. Brain MRI was performed shortly post-TAVI and 6 months later to assess the occurrence of acute silent cerebral ischaemic lesions (SCIL) and chronic white matter hyperintensities (WMH). HALT was screened by cardiac computed tomography (CT) angiography (CTA) 6 months post-TAVI. Neurocognitive evaluation was performed before, shortly after and 6 months following TAVI. At 6 months, 115 patients had diagnostic CTA and 10 had HALT. HALT status, baseline, and follow-up MRIs were available in 91 cases. At 6 months, new SCIL was evident in 16%, new WMH in 66%. New WMH was more frequent (100 vs. 62%; P = 0.047) with higher median volume (319 vs. 50 mm3; P = 0.039) among HALT-patients. In uni- and multivariate analysis, HALT was associated with new WMH volume (beta: 0.72; 95%CI: 0.2-1.39; P = 0.009). The patients' cognitive trajectory from pre-TAVI to 6 months showed significant association with the 6-month SCIL volume (beta: -4.69; 95%CI: -9.13 to 0.27; P = 0.038), but was not related to the presence or volume of new WMH. During a 3.1-year follow-up, neither HALT [hazard ratio (HR): 0.86; 95%CI: 0.202-3.687; P = 0.84], nor the related WMH burden (HR: 1.09; 95%CI: 0.701-1.680; P = 0.71) was related with increased mortality.

CONCLUSIONS

At 6 months post-TAVI, HALT was linked with greater WMH burden, but did not carry an increased risk of cognitive decline or mortality over a 3.1-year follow-up (NCT02826200).

Deformation of Transcatheter Aortic Valve Prostheses: Implications for Hypoattenuating Leaflet Thickening and Clinical Outcomes

BACKGROUND

Although transcatheter aortic valve replacement (TAVR) therapy continues to grow, there have been concerns about the occurrence of hypoattenuating leaflet thickening (HALT), which may affect prosthesis function or durability. This study aimed to examine prosthesis frame factors and correlate their extent to the frequency of HALT and clinical outcomes.

METHODS

We prospectively examined 565 patients with cardiac computed tomography screening for HALT at 30 days after balloon-expandable SAPIEN3 and self-expanding EVOLUT TAVR. Deformation of the TAVR prostheses, asymmetric prosthesis leaflet expansion, prosthesis sinus volumes, and commissural alignment were analyzed on the postprocedural computed tomography. For descriptive purposes, an index of prosthesis deformation was calculated, with values >1.00 representing relative midsegment underexpansion. A time-to-event model was performed to evaluate the association of HALT with the clinical outcome.

RESULTS

Overall, HALT was present in 21% of SAPIEN3 patients and in 16% of EVOLUT patients at 30 days after TAVR. The occurrence of HALT was directly associated with greater prosthesis frame deformation (P<0.001), worse asymmetry of the leaflets (P<0.001), and smaller TAVR neosinus volumes (P<0.001). These relations were present in both prosthetic types and in all of their size ranges (all P<0.05). In multivariable analyses that include clinical variables previously associated with HALT (eg, anticoagulant therapy), variables of TAVR prosthesis deformation remained predictive of HALT. Although HALT was not associated with changes in prosthetic hemodynamics, its presence was associated with the risk of mortality at 1 year, with respect to greater incidences of all-cause mortality (hazard ratio, 2.98 [95% CI, 1.57-5.63]; P=0.001), cardiac death (hazard ratio, 4.58 [95% CI, 1.81-11.6]; P=0.001), and a composite outcome of all-cause mortality and heart failure hospitalization (hazard ratio, 1.94 [95% CI, 1.14-3.30]; P=0.02) with adjustment for age, sex, and comorbidities.

CONCLUSIONS

Nonuniform expansion of TAVR prostheses resulting in frame deformation, asymmetric leaflet, and smaller neosinus volume is related to occurrence of HALT in patients who undergo TAVR. These data may have implications for both prosthesis valve design and deployment techniques to improve clinical outcomes for these patients.

DNA Origami-Platelet Adducts: Nanoconstruct Binding without Platelet Activation

Objective. Platelets are small, mechanosensitive blood cells responsible for maintaining vascular integrity and activatable on demand to limit bleeding and facilitate thrombosis. While circulating in the blood, platelets are exposed to a range of mechanical and chemical stimuli, with the platelet membrane being the primary interface and transducer of outside-in signaling. Sensing and modulating these interface signals would be useful to study mechanochemical interactions; yet, to date, no methods have been defined to attach adducts for sensor fabrication to platelets without triggering platelet activation. We hypothesized that DNA origami, and methods for its attachment, could be optimized to enable nonactivating instrumentation of the platelet membrane. Approach and Results. We designed and fabricated multivalent DNA origami nanotile constructs to investigate nanotile hybridization to membrane-embedded single-stranded DNA-tetraethylene glycol cholesteryl linkers. Two hybridization protocols were developed and validated (Methods I and II) for rendering high-density binding of DNA origami nanotiles to human platelets. Using quantitative flow cytometry, we showed that DNA origami binding efficacy was significantly improved when the number of binding overhangs was increased from two to six. However, no additional binding benefit was observed when increasing the number of nanotile overhangs further to 12. Using flow cytometry and transmission electron microscopy, we verified that hybridization with DNA origami constructs did not cause alterations in the platelet morphology, activation, aggregation, or generation of platelet-derived microparticles. Conclusions. Herein, we demonstrate that platelets can be successfully instrumented with DNA origami constructs with no or minimal effect on the platelet morphology and function. Our protocol allows for efficient high-density binding of DNA origami to platelets using low quantities of the DNA material to label a large number of platelets in a timely manner. Nonactivating platelet-nanotile adducts afford a path for advancing the development of DNA origami nanoconstructs for cell-adherent mechanosensing and therapeutic agent delivery.

Long-Term Follow-Up of Hypoattenuated Leaflet Thickening After Transcatheter Aortic Valve Replacement

BACKGROUND

Early hypoattenuated leaflet thickening (HALT) occurs in at least 10% of all transcatheter aortic valve replacement (TAVR) patients. The long-term prognostic impact of HALT is uncertain.

OBJECTIVES

The aim of this study was to assess the long-term risk of early HALT post-TAVR.

METHODS

We report outcome data from our prospective observational registry with post-TAVR computed tomography angiography performed between May 2012 and December 2017. The outcomes were survival, cardiovascular mortality, ischemic cerebrovascular events, and symptomatic hemodynamic valve deterioration.

RESULTS

Early HALT was diagnosed in 115 (16.0%) of 804 patients. During a median follow-up of 3.25 years, survival rates did not differ significantly between patients with and without HALT (Kaplan-Meier 3-year estimates for survival 70.1% vs 74.0%, P = 0.597). The 3-year cardiovascular mortality rate was 13.2% versus 11.3% (with vs without HALT, P = 0.733). The 3-year event rate for cerebrovascular events was 2.0% versus 4.4% (with vs without HALT, P = 0.246), and the 3-year event rate of symptomatic hemodynamic valve deterioration was 9.4% versus 1.5% (with vs without HALT, P < 0.001). Multivariable analysis revealed the following predictors of symptomatic hemodynamic valve deterioration: HALT (HR: 6.10; 95% CI: 2.59-14.29; P < 0.001), the mixed valve-type group (HR: 6.51; 95% CI: 2.38-17.81; P < 0.001), and prosthesis diameter (HR valve size per 3 mm [HR: 0.37; 95% CI: 0.17-0.79]; P = 0.011).

CONCLUSIONS

During a median follow-up of more than 3 years, HALT was not associated with mortality or cerebrovascular events. However, we observed an association of HALT with symptomatic hemodynamic valve deterioration.

18F-GP1 Positron Emission Tomography and Bioprosthetic Aortic Valve Thrombus

BACKGROUND

Bioprosthetic valve thrombosis may have implications for valve function and durability.

OBJECTIVES

Using a novel glycoprotein IIb/IIIa receptor radiotracer 18F-GP1, we investigated whether positron emission tomography (PET)-computed tomography (CT) could detect thrombus formation on bioprosthetic aortic valves.

METHODS

Ex vivo experiments were performed on human platelets and explanted bioprosthetic aortic valves. In a prospective cross-sectional study, patients with either bioprosthetic or normal native aortic valves underwent echocardiography, CT angiography, and 18F-GP1 PET-CT.

RESULTS

Flow cytometric analysis, histology, immunohistochemistry, and autoradiography demonstrated selective binding of 18F-GP1 to activated platelet glycoprotein IIb/IIIa receptors and thrombus adherent to prosthetic valves. In total, 75 participants were recruited: 53 with bioprosthetic valves (median time from implantation 37 months [IQR: 12-80 months]) and 22 with normal native aortic valves. Three participants had obstructive valve thrombosis, and a further 3 participants had asymptomatic hypoattenuated leaflet thickening on CT angiography. All bioprosthetic valves, but none of the native aortic valves, demonstrated focal 18F-GP1 uptake on the valve leaflets: median maximum target-to-background ratio 2.81 (IQR: 2.29-3.48) vs 1.43 (IQR: 1.28-1.53) (P < 0.001). Higher 18F-GP1 uptake was independently associated with duration of valve implantation and hypoattenuated leaflet thickening. All 3 participants with obstructive valve thrombosis were anticoagulated for 3 months, leading to resolution of their symptoms, improvement in mean valve gradients, and a reduction in 18F-GP1 uptake.

CONCLUSIONS

Adherence of activated platelets is a common and sustained finding on bioprosthetic aortic valves. 18F-GP1 uptake is higher in the presence of thrombus, regresses with anticoagulation, and has potential use as an adjunctive clinical tool. (18F-GP1 PET-CT to Detect Bioprosthetic Aortic Valve Thrombosis; NCT04073875).

Biomechanics of Transcatheter Aortic Valve Replacement Complications and Computational Predictive Modeling

Transcatheter aortic valve replacement (TAVR) is a rapidly growing field enabling replacement of diseased aortic valves without the need for open heart surgery. However, due to the nature of the procedure and nonremoval of the diseased tissue, there are rates of complications ranging from tissue rupture and coronary obstruction to paravalvular leak, valve thrombosis, and permanent pacemaker implantation. In recent years, computational modeling has shown a great deal of promise in its capabilities to understand the biomechanical implications of TAVR as well as help preoperatively predict risks inherent to device-patient-specific anatomy biomechanical interaction. This includes intricate replication of stent and leaflet designs and tested and validated simulated deployments with structural and fluid mechanical simulations. This review outlines current biomechanical understanding of device-related complications from TAVR and related predictive strategies using computational modeling. An outlook on future modeling strategies highlighting reduced order modeling which could significantly reduce the high time and cost that are required for computational prediction of TAVR outcomes is presented in this review paper. A summary of current commercial/in-development software is presented in the final section.

Aortic Sinus Contrast Retention During TAVR

Sinus contrast material retention after transcatheter aortic valve replacement (TAVR) is a rare phenomenon that may reflect an increased risk for thrombotic complications. We present 3 cases of persistent contrast agent retention in the sinus of Valsalva during the TAVR procedure that portend the occurrence of embolic stroke or bioprosthetic valve thrombosis. (Level of Difficulty: Advanced.)

Off-Label Use and Inappropriate Dosing of Direct Oral Anticoagulants in Cardiopulmonary Disease

Direct oral anticoagulants (DOACs) are increasingly used in clinical practice and have become essential in the management of atrial fibrillation and VTE. The enthusiasm for DOACs has fueled the off-label application of these agents in cardiopulmonary disease, and their use has often outpaced the evidence supporting their application. This article reviews the evidence and current off-label use of DOACs in various cardiopulmonary disease states.

Antithrombotic Therapy Following Transcatheter Aortic Valve Replacement

Due to a large technical improvement in the past decade, transcatheter aortic valve replacement (TAVR) has expanded to lower-surgical-risk patients with symptomatic and severe aortic stenosis. While mortality rates related to TAVR are decreasing, the prognosis of patients is still impacted by ischemic and bleeding complications, and defining the optimal antithrombotic regimen remains a priority. Recent randomized control trials reported lower bleeding rates with an equivalent risk in ischemic outcomes with single antiplatelet therapy (SAPT) when compared to dual antiplatelet therapy (DAPT) in patients without an underlying indication for anticoagulation. In patients requiring lifelong oral anticoagulation (OAC), the association of OAC plus antiplatelet therapy leads to a higher risk of bleeding events with no advantages on mortality or ischemic outcomes. Considering these data, guidelines have recently been updated and now recommend SAPT and OAC alone for TAVR patients without and with a long-term indication for anticoagulation. Whether a direct oral anticoagulant or vitamin K antagonist provides better outcomes in patients in need of anticoagulation remains uncertain, as recent trials showed a similar impact on ischemic and bleeding outcomes with apixaban but higher gastrointestinal bleeding with edoxaban. This review aims to summarize the most recently published data in the field, as well as describe unresolved issues.

Performance of Computed Tomography Angiography (CTA) for the Diagnosis of Hypo-Attenuated Leaflet Thickening (HALT)

(1) Background: Early hypo-attenuated leaflet thickening (HALT) is diagnosed by computed tomography angiography (CTA) in approximately 15% of patients undergoing transcatheter aortic valve replacement (TAVR). We sought to investigate the diagnostic performance of CTA for the diagnosis of HALT, focusing on timing data assessment within the cardiac cycle. (2) Methods: The study enrolled 50 patients with and 50 without HALT with available post-TAVR-CTA. The primary objective was to compare the diagnostic performance of CTA readings at specific intervals and time points during the cardiac cycle (entire systole, entire diastole, end-systole, and mid-diastole) versus gold standard (consensus reading by two observers based on multiphase full cardiac cycle data sets). (3) Results: 100 CTAs were independently analysed by two observers blinded to clinical characteristics of the study population and the results from the gold standard reading. Sensitivity and specificity for the diagnosis of HALT were 84%/94% in systole, 87%/92% in diastole, 78%/95% at end-systole, and 80%/94% at mid-diastole. End-systole had the highest positive predictive value (0.88) and positive likelihood ratio (36). Cohen’s kappa for interobserver reliability was 0.715 in systole, 0.578 in diastole, 0.650 at end-systole, and 0.517 at mid-diastole. (4) Conclusion: Limiting CTA reading to distinct intervals or time points during the cardiac cycle has good specificity but lowers sensitivity. For a reliable diagnosis of HALT, data sets from a multiphase CTA covering the entire cardiac cycle should be analysed. A double reader approach would be desirable in further studies investigating HALT.

Clinical applications of cardiac computed tomography: a consensus paper of the European Association of Cardiovascular Imaging-part II

Cardiac computed tomography (CT) was initially developed as a non-invasive diagnostic tool to detect and quantify coronary stenosis. Thanks to the rapid technological development, cardiac CT has become a comprehensive imaging modality which offers anatomical and functional information to guide patient management. This is the second of two complementary documents endorsed by the European Association of Cardiovascular Imaging aiming to give updated indications on the appropriate use of cardiac CT in different clinical scenarios. In this article, emerging CT technologies and biomarkers, such as CT-derived fractional flow reserve, perfusion imaging, and pericoronary adipose tissue attenuation, are described. In addition, the role of cardiac CT in the evaluation of atherosclerotic plaque, cardiomyopathies, structural heart disease, and congenital heart disease is revised.

Impact of Systemic Inflammatory Response Syndrome on Clinical, Echocardiographic, and Computed Tomographic Outcomes Among Patients Undergoing Transcatheter Aortic Valve Implantation

Background

Systemic inflammatory response syndrome (SIRS) is a systemic insult that has been described with many interventional cardiac procedures. The outcomes of patients undergoing transcatheter aortic valve implantation (TAVI) are thought to be influenced by this syndrome not only on short-term, but also on long-term.

Objective

We assessed the association of SIRS to different clinical, echocardiographic, and computed tomographic (CT) outcomes after TAVI.

Methods

Two hundred and twenty-four consecutive patients undergoing TAVI were enrolled in this study. They were assessed for the occurrence of SIRS within the first 48 h after TAVI. Patients were followed-up for short- and long-term clinical outcomes. Serial echocardiographic follow-ups were conducted at 1-week, 6-months, and 1-year. CT follow-up at 1 year was recorded.

Results

Eighty patients (36%) developed SIRS. Among different parameters, only pre-TAVI total leucocytic count (TLC), pre-TAVI heart rate, and post-TAVI systolic blood pressure independently predicted the occurrence of SIRS. The incidence of HALT was not significantly different between both groups, albeit higher among SIRS patients (p = 0.1) at 1-year CT follow-up. Both groups had similar patterns of LV recovery on serial echocardiography. Long-term follow-up showed that all-cause death, cardiac death, and re-admission for heart failure (HF) or acute coronary syndrome (ACS) were significantly more frequent among SIRS patients. Early safety and clinical efficacy outcomes were more frequently encountered in the SIRS group, while device-related events and time-related valve safety were comparable.

Conclusion

Although SIRS implies an early acute inflammatory status post-TAVI, yet its clinical sequelae seem to extend to long-term clinical outcomes.

Treatment of Bicuspid Aortic Valve Stenosis with TAVR: Filling Knowledge Gaps Towards Reducing Complications

PURPOSE OF REVIEW

Bicuspid aortic valve (BAV) disease is the most common congenital heart defect worldwide. When severe, symptomatic aortic stenosis ensues, the treatment has increasingly become transcatheter aortic valve replacement (TAVR). The purpose of this review is to identify BAV classification and imaging methods, outline TAVR outcomes in BAV anatomy, and discuss how computational modeling can enhance TAVR treatment in BAV patients.

RECENT FINDINGS

TAVR use in BAV patients, when compared to use in tricuspid aortic valves, showed lower device success rate, and there remains no long-term randomized trial data. It has been reported that BAV patients with severe calcification increase the rate of complications. Additionally, the asymmetrical morphology of BAVs often results in asymmetric stent geometries which have implications for increased thrombosis risk and decreased durability. These adverse outcomes are currently very difficult to predict from routine pre-procedural imaging alone. Recently developed patient specific experimental and computational techniques have the potential to assist in filling knowledge gaps in the mechanisms of these complications and provide more information during preclinical planning for better TAVR selection in low surgical risk BAV patients. Efficacy of TAVR for irregular BAV anatomies remains concerning due to the lack of a long-term randomized trial data, their increased rate of short-term complications, and signs that long-term durability could be an issue. More knowledge on identifying which BAV anatomies are at greater risk for these adverse outcomes can potentially improve patient selection for TAVR versus SAVR in low surgical risk BAV patients.

Subclinical Leaflets Thrombosis After Transcatheter Replacement of Bicuspid vs. Tricuspid Aortic Valve

Background: Subclinical leaflet thrombosis (SLT) is an important sequela that compromises the durability of the bioprosthetic valve. Objectives: To better determine the effect of SLT in bicuspid aortic valve (BAV), we performed a retrospective assessment of CT-defined SLT in BAV and tricuspid aortic valve (TAV) stenotic patients. Methods: We consecutively collected patients undergoing the TAVR between August 2015 and March 2020 in our center. A total of 170 BAV and 201 TAV cases were enrolled. Multidetector computed tomography was performed within 30 days and at 1-year. Results: Twenty cases in the BAV group and 19 cases in the TAV group had hypoattenuated leaflet thickening (HALT) in 30 days (12.5 vs. 9.9%, p = 0.449), and 52 cases in BAV and 61 cases in TAV had the HALT (34.9 vs. 36.7%, p = 0.733) at 1-year follow-up. The mean aortic gradient (MAG) and effective orifice areas (EOA) values were comparable between the two groups at 30 days (HALT vs. no HALT; 10.8 ± 4.8 vs. 11.3 ± 6.0, p = 0.638; 1.6 ± 0.4 vs. 1.6 ± 0.3, p = 0.724), and still, no difference was observed in the MAG at 1-year (11.5 ± 5.6 vs. 10.6 ± 5.1, p = 0.164). However, the EOA at 1-year was statistically different between the two groups (1.5 ± 0.3 vs. 1.6 ± 0.4, p = 0.004). The multivariate logistic regression analysis demonstrated the anticoagulation and age as independent predictors both in the BAV and TAV groups at 1-year. There was no difference in clinical events between the HALT and no HALT group in relevant to BAV or TAV at 1-year follow-up. Conclusions: The presence of subclinical leaflet thrombosis defined by the CT was comparable between the BAV and TAV in the first year after the TAVR procedure. Age and anticoagulation were the independent predictors of the subclinical leaflet thrombosis at 1 year after the TAVR. There was no difference in relevant clinical events between the BAV and TAV groups at 1-year follow-up.

Neosinus and Sinus Flow After Self-Expanding and Balloon-Expandable Transcatheter Aortic Valve Replacement

OBJECTIVES

The aim of this study was to evaluate flow dynamics in the aortic sinus and the neosinus (NS) after transcatheter heart valve (THV) implantation in valve-in-valve (ViV).

BACKGROUND

Leaflet thrombosis may occur on THVs and affect performance and durability. Differences in flow dynamics may affect the risk for leaflet thrombosis.

METHODS

Hemodynamic assessment following THV implantation in a surgical aortic valve was performed in a left heart simulator under pulsatile physiological conditions. Assessment was performed using a 23-mm polymeric surgical aortic valve (not diseased) and multiple THV platforms, including self-expanding devices (26-mm Evolut, 23-mm Allegra, small ACURATE neo) and a balloon-expandable device (23-mm SAPIEN 3). Particle image velocimetry was performed to assess flow in the sinus and NS. Sinus and NS washout, shear stress, and velocity were calculated.

RESULTS

Sinus and NS washout was fastest and approximately 1 cardiac cycle for each with the Evolut, ACURATE neo, and Allegra compared with the SAPIEN 3, with washout in 2 and 3 cardiac cycles, respectively. The Allegra showed the largest shear stress distribution in the sinus, followed by the SAPIEN 3. In the NS, all 4 valves showed equal likelihoods of occurrence of shear stress <1 Pa, but the Allegra showed the highest likelihoods of occurrence for shear stress >1 Pa. The velocities in the sinus and NS were 0.05, 0.078, 0.080, and 0.075 m/s for Evolut, SAPIEN 3, ACURATE neo, and Allegra ViV, respectively.

CONCLUSIONS

Sinus and NS flow dynamics differ substantially among THVs after ViV. Self-expanding supra-annular valves seem to have faster washouts compared with an equivalent-size balloon-expandable THV.

Subclinical Leaflet Thrombosis After Transcatheter Aortic Valve Replacement: A Meta-Analysis

This meta-analysis and systematic review was performed to evaluate the clinical relevance of subclinical leaflet thrombosis (SLT) following transcatheter aortic valve replacement. PubMed, Web of Science, and CENTRAL were searched for eligible randomized and nonrandomized studies until November 2020. Risk ratios (RRs) or odds ratios and 95% CIs were calculated, using a random-effects model. Overall, 25 studies were eligible for the analysis and comprised a total of 11,098 patients. The median incidence of SLT was 6% at a median follow-up of 30 days. Use of intra-annular valves was associated with 2-fold greater risk for the development of SLT compared with use of supra-annular valves. There was no difference in the risk for SLT (RR: 0.97; 95% CI: 0.72-1.29; P = 0.83) between single-antiplatelet therapy (SAPT) and dual-antiplatelet therapy (DAPT), whereas oral anticoagulation (OAC) was associated with a 58% relative risk reduction for SLT (RR: 0.42; 95% CI: 0.29-0.61; P < 0.00001) compared with SAPT and DAPT. In patients with diagnosed leaflet thrombosis at follow-up, the risk for stroke or transient ischemic attack was increased by 2.6-fold (RR: 2.56; 95% CI: 1.60-4.09; P < 0.00001) compared with patients without leaflet thrombosis. In patients diagnosed with SLT, the odds of SLT resolution increased by 99% after switch from antiplatelet agents to OAC (odds ratio: 0.01; 95% CI: 0.00-0.06; P < 0.00001). To summarize, indication-based use of OAC after transcatheter aortic valve replacement is associated with a lower risk for SLT compared with SAPT and DAPT. Switching to OAC seems to be effective for SLT resolution. As SLT increased the odds of stroke or transient ischemic attack in the included population, further studies are needed to investigate whether screening tests for SLT and appropriate antithrombotic therapy improve long-term valve functionality and clinical prognosis.

Predictive Model for Thrombus Formation After Transcatheter Valve Replacement

PURPOSE

Leaflet thrombosis is a significant adverse event after transcatheter aortic valve (TAV) replacement (TAVR). The purpose of our study was to present a semi-empirical, mathematical model that links patient-specific anatomic, valve, and flow parameters to predict likelihood of leaflet thrombosis.

METHODS

The two main energy sources of neo-sinus (NS) washout after TAVR include the jet flow downstream of the TAV and NS geometric change in volume due to the leaflets opening and closing. Both are highly dependent on patient anatomic and hemodynamic factors. As rotation of blood flow is prevalent in both the sinus of Valsalva and then the NS, we adopted the vorticity flux or circulation (Г) as a metric quantifying overall washout. Leaflet thrombus volumes were segmented based on hypo-attenuating leaflet thickening (HALT) in post-TAVR patient's gated computed tomography. Г was assessed using dimensional scaling as well as computational fluid dynamics (CFD) respectively and correlated to the thrombosis volumes using sensitivity and specificity analysis.

RESULTS

Г in the NS, that accounted for patient flow and anatomic conditions derived from scaling arguments significantly better predicted the occurrence of leaflet thrombus than CFD derived measures such as stasis volumes or wall shear stress. Given results from the six patient datasets considered herein, a threshold Г value of 28.0 yielded a sensitivity and specificity of 100% where patients with Gamma < 28 developed valve thrombosis. A 10% error in measurements of all variables can bring the sensitivity specificity down to 87%.

CONCLUSION

A predictive model relating likelihood of valve thrombosis using Г in the NS was developed with promising sensitivity and specificity. With further studies and improvements, this predictive technology may lead to alerting physicians on the risk for thrombus formation following TAVR.

Baseline mean platelet volume is a strong predictor of major and life-threatening bleedings after transcatheter aortic valve replacement

BACKGROUND

Bleeding following transcatheter aortic valve replacement (TAVR) has important prognostic implications. This study sought to evaluate the impact of baseline mean platelet volume (MPV) on bleeding events after TAVR.

METHODS AND RESULTS

Patients undergoing TAVR between February 2010 and May 2019 were included. Low MPV (L-MPV) was defined as MPV ≤10 fL and high MPV (H-MPV) as MPV >10 fL. The primary endpoint was the occurrence of major/life-threatening bleeding complications (MLBCs) at one-year follow-up. Among 1,111 patients, 398 (35.8%) had L-MPV and 713 (64.2%) had H-MPV. The rate of MLBCs at 1 year was higher in L-MPV patients compared with H-MPV patients (22.9% vs. 17.7% respectively, p = 0.034). L-MPV was associated with vascular access-site complications (36.2% vs. 28.9%, p = 0.012), early (<30 days) major bleeding (15.6% vs. 9.4%, p<0.01) and red blood cell transfusion >2 units (23.9% vs. 17.5%, p = 0.01). No impact of baseline MPV on overall death, cardiovascular death and ischemic events (myocardial infarction and stroke) was evidenced. Multivariate analysis using Fine and Gray model identified preprocedural hemoglobin (sHR 0.84, 95%CI [0.75-0.93], p = 0.001), preprocedural L-MPV (sHR 1.64, 95%CI [1.16-2.32], p = 0.005) and closure time adenosine diphosphate post-TAVR (sHR 2.71, 95%CI [1.87-3.95], p<0.001) as predictors of MLBCs.

CONCLUSIONS

Preprocedural MPV was identified as an independent predictor of MLBCs one year after TAVR, regardless of the extent of platelet inhibition and primary hemostasis disorders.

Transcatheter aortic valve thrombosis: a review of potential mechanisms

Transcatheter aortic valve (TAV) thrombosis has been recognized as a significant problem that sometimes occurs as early as within 30 days after valve implantation, leading to increased concerns of stroke and long-term valve durability. In this article, a critical summary of the relevant literature on identifying potential mechanisms of TAV thrombosis from the perspective of the well-known Virchow's triad, which comprises blood flow, foreign materials and blood biochemistry, is presented. Blood flow mechanisms have been the primary focus thus far, with a general consensus on the flow mechanisms with respect to haemodynamic conditions, the influence of TAV placement and expansion and the influence of coronary flow. Less attention has been paid to the influence of blood biochemistry and foreign materials (and related endothelial damage), with little consensus among studies with regards to platelet and/or microparticle levels post-TAV implantation. Finally, we discuss the future outlook for research with unanswered scientific questions.

Transcatheter Aortic Valve Leaflet Thrombosis: Prevalence, Management, and Future Directions

PURPOSE OF REVIEW

We review the pathology, prevalence, diagnosis, hemodynamics, risk factors, prognosis, and treatment of leaflet thrombosis (LT), and suggest future directions in this field.

RECENT FINDINGS

The latest meta-analysis showed the prevalence of overall LT is 5.4% (clinical LT of 1.2% and subclinical LT of 15.1%). Either subclinical or clinical LT is not associated with risk of mortality; however, clinical LT is associated with increased risk of stroke. Although LT can be reduced by oral anticoagulation therapy (OAT), routine use of OAT as primary prevention for high-risk patients is not recommended due to increased risk of mortality. Four-dimensional computed tomography plays an important role in the diagnosis of LT and the accumulation of qualitative or qualitative assessments of hypoattenuated leaflet thickening would provide more clues to clarify effective OAT strategies. In addition, further studies are warranted to evaluate the efficacy of other anticoagulants in low-intermediate risk patients.

Thrombose et TAVI : beaucoup de questions restent sans réponses

Over the past decade, TAVI has become the standard technique for treatment of severe symptomatic aortic stenosis in patients at high or intermediate surgical risk and more recently in low-surgical-risk patients. Like any technique, TAVI is associated with certain complications such as post-TAVI thrombosis. This complication can have clinical manifestations with recurrence of symptoms and/or increase in trans-prosthetic gradients. It can also be infraclinical, i.e asymptomatic without trans-prosthetic gradient elevation as revealed by cardiac CT scan showing a thickening of the valvular leaflets or cusp thrombosis, with potential impairment of the valve opening. This greatly underestimated complication has a 10% to 15% incidence. Biomechanical factors, intrinsic patient-related predisposition as well as post-TAVI anti-thrombotic treatment have all been incriminated in the occurrence of TAVI thrombosis. The use of anticoagulation treatment by AVK or DOAC in the presence of post TAVI prosthetic thrombosis seems obvious. However, their benefit in the treatment of infraclinical thrombosis has not been clearly established.

How to reduce uncommon but severe transcatheter aortic valve implantation complications: stroke, thrombosis, endocarditis, cognitive decline?

Transcatheter aortic valve implantation has become a valid alternative to surgical aortic valve replacement for patients with symptomatic severe aortic stenosis, regardless of baseline surgical risk. The incidence of periprocedural complications has steadily declined over the years, thanks to technical advancement of transcatheter heart valves, delivery systems, and increased operators' experience. Beyond the most common periprocedural complications, there are a few uncommon but potentially severe complications that more often occur during follow-up, although they may also arise in the periprocedural phase. Stroke, infective endocarditis, valve thrombosis, and cognitive decline are among them. In this brief review, we describe the incidence, predictive factors, and potential preventive measures for those events.

Diagnosis and Treatment of Intracardiac Thrombus

ABSTRACT

Intracardiac thrombi can occur in a variety of locations and are frequently encountered in clinical practice. Yet evidence-based guidance for clinicians managing patients with intracardiac thrombi is often limited. This review summarizes what is known regarding the prevalence of intracardiac thrombus, diagnostic strategies, clinical relevance, and treatment options, focusing on four specific types of thrombus for which recent research has shifted clinical understanding and treatment decisions: (1) left atrial appendage thrombus, (2) cardiac implantable electronic device lead thrombus, (3) bioprosthetic aortic valve thrombus, and (4) left ventricular thrombus. Additional studies, ideally prospective, randomized, and head-to-head in design, are needed to better inform best practices in patients with intracardiac thrombi.

Transcatheter aortic valve thrombosis: Data from a French multicenter cohort analysis

OBJECTIVES

To evaluate the effectiveness of anticoagulant therapies in patients with clinical transcatheter heart valve (THV) thrombosis, to describe complications, and to assess their risk profile was the objectives.

BACKGROUND

Little research has been conducted on clinical THV thrombosis.

METHODS

Patients with clinical THV thrombosis were identified based on greater than 50% increased transvalvular gradient on transthoracic echocardiogram confirmed by 4-dimensional computed tomography, transesophageal echocardiogram, or regression with anticoagulant therapy. A cohort free from thrombosis for more than 1,100 days postprocedure was used for comparison.

RESULTS

Fifty-four patients with clinical THV thrombosis were identified. Most subjects (98.1%) received anticoagulant therapy which was effective (≥50% reduction in transvalvular gradient or return to postprocedure value) in 96%. The rate of serious hemodynamic or embolic complications in the thrombosis population was 31.5%. A multivariate analysis of subjects with and without thrombosis indicated a significantly increased risk of thrombosis from preexisting thrombocytopenia (odds ratio [OR] 9.96), absence of predilatation (OR = 5.67), renal insufficiency (OR = 4.84), and >10 mmHg mean transvalvular gradient postprocedure (OR = 3.36). No recurrence of thrombosis was identified during on average 685 days follow-up.

CONCLUSIONS

These data, from one of the largest cohorts with clinical THV thrombosis confirm anticoagulants appear effective. The rate of serious associated complications was high. The findings underline the importance of recognizing risk factors for thrombosis.

How to Image and Manage Prosthesis-Related Complications After Transcatheter Aortic Valve Replacement

PURPOSE OF REVIEW

In this review, we provide an overview of potential prosthesis - related complications after transcatheter aortic valve replacement, their incidences, the imaging modalities best suited for detection, and possible strategies to manage these complications.

RECENT FINDINGS

Therapy for severe aortic valve stenosis requiring intervention has increasingly evolved toward transcatheter aortic valve replacement over the past decade, and the number of procedures performed has increased steadily in recent years. As more and more centers favor a minimalistic approach and largely dispense with general anesthesia and intra-procedural imaging by transesophageal echocardiography, post-procedural imaging is becoming increasingly important to promptly detect dysfunction of the transcatheter valve and potential complications. Complications after transcatheter aortic valve replacement must be detected immediately in order to initiate adequate therapeutic measures, which require a profound knowledge of possible complications that may occur after transcatheter aortic valve replacement, the imaging modalities best suited for detection, and available treatment options.

Direct Flow Medical vs. Edwards Sapien 3 Prosthesis: A Propensity Matched Comparison on Intermediate Safety and Mortality

Aims: To compare intermediate performance and mortality rates in patients, who underwent transcatheter aortic valve implantation (TAVI) with two different types of prostheses: Edwards Sapien 3 (ES3) and Direct Flow Medical (DFM).

Methods and Results: 42 consecutive patients implanted with a DFM prosthesis for severe aortic stenosis were matched 1:1 with an equal number of patients, who received an ES3 during the same period. Primary endpoint was mortality. MACE, as a composite of all-cause death, stroke, and re-do-procedure (valve-in-valve), was defined as secondary endpoint. Moreover, we compared NYHA class, NT-proBNP-levels and the extent of restenosis. Patients were followed for 2 years. DFM patients showed echocardiographic elevated mean pressure gradients compared to ES3 patients before discharge (11.2 mmHg ± 5.3 vs. 3.5 mmHg ± 2.7; p < 0.001) and upon 6-months follow-up (20.3 mmHg ± 8.8 vs. 12.3 mmHg ± 4.4; p < 0.001). ES3 candidates showed superior NYHA class at follow-up (p = 0.001). Kaplan-Meier analysis revealed significantly worse survival in patients receiving a DFM prosthesis compared to ES3 (Breslow p = 0.020). MACE occurred more often in DFM patients compared to ES3 (Breslow p = 0.006).

Conclusions: Patients receiving DFM valve prostheses showed worse survival and higher rates in MACE compared to ES3. Prosthesis performance regarding mean pressure gradients and patients' NYHA class also favored ES3.

Coagulation derangement and risk factors for valve thrombosis following transcatheter aortic valve implantation

Aims

Durability of transcatheter aortic valve implantation (TAVI) is key to its expansion. We sought to identify incidence of valve thrombosis and predictors of valve thrombosis in our single centre with associated coagulation testing pre-TAVI and post-TAVI.

Methods and results

This single-centre observational study comprised patients undergoing transfemoral TAVI discussed in the Heart Team meeting. Patients were followed up with echocardiography at 120 days to identify incidence of elevated transvalvular gradient and multivariable analysis was performed to identify factors associated with an increased odds of developing valve thrombosis. In addition, 11 patients underwent baseline, day 1 and day 120 post-TAVI coagulation testing. Between August 2017 and August 2019, 437 consecutive patients underwent transfemoral TAVI. Of these patients, 207/437 (47.4%) had 3-month follow-up echo data available and were analysed. Of these patients, 26/207 (12.6%) had elevated transvalvular gradients. These patients tended to be younger (80±14 vs 83±6 years; p=0.047) with a lower ejection fraction (49±13 vs 54%±11%; p=0.021), with a greater proportion of the population experiencing atrial fibrillation (14/21, 54% vs 68/181, 38%; p=0.067). Following multivariable analysis, there remained a trend towards higher eccentricity index associated with elevated gradients. Baseline (pre-TAVI) elevation of thrombin antithrombin levels (56±63; reference range 1.0–4.1 ng/L) and PF 1+2 (791±632; reference range 69–229 ng/mL) normalised at 120 days post-TAVI

Conclusion

This study demonstrated that in the cohort of patients undergoing transfemoral TAVI in our centre: younger age, poor ejection fraction, atrial fibrillation and increased baseline eccentricity of the aortic valve annulus were present to a greater extent in patients exhibiting elevated transvalvular gradients at 3-month follow-up. Further work is required to delineate the extent of coagulation derangement and confirm predictors of thrombosis.

Clinical and Technical Challenges of Prosthesis-Patient Mismatch After Transcatheter Aortic Valve Implantation

Prosthesis-patient mismatch (PPM) is present when the effective area of a prosthetic valve inserted into a patient is inferior to that of a normal human valve; the hemodynamic consequence of a valve too small compared with the size of the patient's body is the generation of higher than expected transprosthetic gradients. Despite evidence of increased risk of short- and long-term mortality and of structural valve degeneration in patients with PPM after surgical aortic valve replacement, its clinical impact in patients subject to transcatheter aortic valve implantation (TAVI) is yet unclear. We aim to review and update on the definition and incidence of PPM after TAVI, and its prognostic implications in the overall population and in higher-risk subgroups, such as small aortic annuli or valve-in-valve procedures. Last, we will focus on the armamentarium available in order to reduce risk of PPM when planning a TAVI procedure.