Possible Subclinical Leaflet Thrombosis in Bioprosthetic Aortic Valves

Outcomes of Redo Transcatheter Aortic Valve Replacement for the Treatment of Postprocedural and Late Occurrence of Paravalvular Regurgitation and Transcatheter Valve Failure

Background—

Transcatheter aortic valves can degenerate in a manner similar to surgical bioprostheses.

Methods and Results—

Clinical and echocardiographic outcomes of patients who underwent redo transcatheter aortic valve replacement (TAVR) procedures >2 weeks post procedure were collected from 14 centers. Among 13 876 patients, 50 (0.4%) underwent redo TAVR procedure at participating centers. Indications for redo TAVR were moderate–severe prosthetic aortic valve stenosis (n=10, 21.7%), moderate–severe central prosthetic aortic valve regurgitation (n=13, 28.3%), and moderate–severe paraprosthetic aortic valve regurgitation (n=25, 50.0%). The index TAVR was most commonly a Medtronic CoreValve (N=38, 76.0%), followed by Edwards SAPIEN-type valves (n=12, 24.0%) and Portico (n=1, 2.0%). The redo TAVR device was most commonly a CoreValve/Evolut R (n=29, 58.0%), followed by a SAPIEN-type valve (n=20,40.0%) or a Boston Lotus valve (n=1, 2.0%). In 40 patients (80.0%), redo TAVR was performed using the identical device type or that of the succeeding generation. Valve performance was uniformly good after redo TAVR (mean transvalvular gradient post redo TAVR: 12.5±6.1 mm Hg). At hospital discharge, all patients remained alive, with 1 nondisabling stroke (2.0%) and 1 life-threatening bleed (2.0%). Permanent pacemaker implantation was required in 3 out of 35 patients without a prior pacemaker (8.6%). Late survival was 85.1% at a median follow-up of 1589 days (range: 31–3775) after index TAVR and 635 days (range: 8–2460) after redo TAVR.

Conclusions—

Redo TAVR for the treatment of postprocedural and late occurrence of paravalvular regurgitation and transcatheter aortic valve prosthesis failure seems to be safe, and it is associated with favorable acute and midterm clinical and echocardiographic outcomes.

Role of Imaging in Transcatheter Aortic Valve Replacement

OPINION STATEMENT

Transcatheter aortic valve replacement (TAVR) has emerged as an effective treatment alternative in patients with severe aortic stenosis (AS) who are deemed surgically high-risk or ineligible for surgery. Pre-procedural imaging, in particular computed tomography (CT), plays an integral part in the planning and performance of TAVR and is crucial for a successful treatment. Novel technological advances in CT include high-pitch, low kV acquisitions, and iterative reconstruction resulting in high image quality at substantially reduced scan duration, contrast volume, and radiation exposure. Given the high spatial and temporal resolution of the acquisitions, CT angiography provides critical information on the eligibility for the peripheral vascular access, aortic root assessment, as well as the aortic annulus measurements, including the coronary ostia and concomitant cardiac pathology. Pre-procedural CT imaging is key for appropriate device size selection to minimize peri-procedural complications and optimize procedural success. In this article, we review the current state of imaging in the pre-interventional setting of TAVR with a special emphasis on CT.

Transcatheter Aortic Valve Thrombosis: Incidence, Predisposing Factors, and Clinical Implications

BACKGROUND

There are limited data on the incidence, clinical implications, and predisposing factors of transcatheter heart valve (THV) thrombosis following transcatheter aortic valve replacement (TAVR).

OBJECTIVES

The authors assessed the incidence, potential predictors, and clinical implications of THV thrombosis as determined by contrast-enhanced multidetector computed tomography (MDCT) after TAVR.

METHODS

Among 460 consecutive patients who underwent TAVR with the Edwards Sapien XT or Sapien 3 (Edwards Lifesciences, Irvine, California) THV, 405 (88%) underwent MDCT in addition to transthoracic and transesophageal echocardiography 1 to 3 months post-TAVR. MDCT scans were evaluated for hypoattenuated leaflet thickening that indicated THV thrombosis.

RESULTS

MDCT verified THV thrombosis in 28 of 405 (7%) patients. A total of 23 patients had subclinical THV thrombosis, whereas 5 (18%) patients experienced clinically overt obstructive THV thrombosis. THV thrombosis risk did not differ among different generations of THVs (8% vs. 6%; p = 0.42). The risk of THV thrombosis in patients who did not receive warfarin was higher compared with patients who received warfarin (10.7% vs. 1.8%; risk ratio [RR]: 6.09; 95% confidence interval [CI]: 1.86 to 19.84). A larger THV was associated with an increased risk of THV thrombosis (p = 0.03). In multivariable analysis, a 29-mm THV (RR: 2.89; 95% CI: 1.44 to 5.80) and no post-TAVR warfarin treatment (RR: 5.46; 95% CI: 1.68 to 17.7) independently predicted THV thrombosis. Treatment with warfarin effectively reverted THV thrombosis and normalized THV function in 85% of patients as documented by follow-up transesophageal echocardiography and MDCT.

CONCLUSIONS

Incidence of THV thrombosis in this large study was 7%. A larger THV size may predispose to THV thrombosis, whereas treatment with warfarin appears to have a protective effect. Although often subclinical, THV thrombosis may have important clinical implications.

Morphology, Clinicopathologic Correlations, and Mechanisms in Heart Valve Health and Disease

The clinical and pathological features of the most frequent intrinsic structural diseases that affect the heart valves are well established, but heart valve disease mechanisms are poorly understood, and effective treatment options are evolving. Major advances in the understanding of the structure, function and biology of native valves and the pathobiology, biomaterials and biomedical engineering, and the clinical management of valvular heart disease have occurred over the past several decades. This communication reviews contemporary considerations relative to the pathology of valvular heart disease, including (1) clinical significance and epidemiology of valvular heart disease; (2) functional and dynamic valvular macro-, micro- and ultrastructure; (3) causes, morphology and mechanisms of human valvular heart disease; and (4) pathologic considerations in valve replacement, repair and, potentially, regeneration of the heart valves.

Microparticles in patients undergoing transcatheter aortic valve implantation (TAVI)

Degenerative aortic stenosis (AS) is the most frequent form of acquired valvular heart disease. AS is known to entail endothelial dysfunction caused by increased mechanical shear stress leading to elevated circulatory levels of microparticles. Endothelial and platelet microparticles (EMP and PMP) are small vesicles that originate from activated cells and thrombocytes. We sought to evaluate whether transcatheter aortic valve implantation (TAVI) procedure would elicit effects on circulating EMP and PMP. 92 patients undergoing TAVI procedure for severe AS were included in this study. Samples were obtained at each visit before TAVI, 1 week post-procedure and at 1, 3 and after 6 months after TAVI and were evaluated using flow cytometry. A 12 month clinical follow-up was also performed. CD62E+ EMP concentration before TAVI was 21.11 % (±6.6 % SD) and declined to 20.99 % (±6.8 % SD) after 1 week, to 16.63 % (±5.4 % SD, p < 0.0001) after 1 month, to 17.08 % (±4.6 % SD, p < 0.0001) after 3 months and to 15.94 % (±5.4 % SD, p < 0.0001) after 6 months. CD31+/CD42b-, CD31+/Annexin+/- EMP remained unchanged. CD31+/CD41b+ PMP evidenced a slight, but statistically significant increase after TAVI and remained elevated during the entire follow-up. Apart from a procedure-related improvement in echocardiographic parameters, TAVI procedure led also to a decline in CD62E+ EMP. The reduction in pressure gradients with less hemodynamic shear stress seems also to have beneficially affected endothelial homeostasis.

Cardiac surgery 2015 reviewed

For the year 2015, almost 19,000 published references can be found in PubMed when entering the search term "cardiac surgery". The last year has been again characterized by lively discussions in the fields where classic cardiac surgery and modern interventional techniques overlap. Lacking evidence in the field of coronary revascularization with either percutaneous coronary intervention or bypass surgery has been added. As in the years before, CABG remains the gold standard for the revascularization of complex stable triple-vessel disease. Plenty of new information has been presented comparing the conventional to transcatheter aortic valve implantation (TAVI) demonstrating similar short- and mid-term outcomes at high and low risk, but even a survival advantage with transfemoral TAVI at intermediate risk. In addition, there were many relevant and interesting other contributions from the purely operative arena. This review article will summarize the most pertinent publications in the fields of coronary revascularization, surgical treatment of valve disease, heart failure (i.e., transplantation and ventricular assist devices), and aortic surgery. While the article does not have the expectation of being complete and cannot be free of individual interpretation, it provides a condensed summary that is intended to give the reader "solid ground" for up-to-date decision-making in cardiac surgery.

Clinical trials in transcatheter aortic valve replacement

PURPOSE OF REVIEW

Clinical trials in transcatheter aortic valve replacement (TAVR) have been essential in establishing the effectiveness as well as the limitations of this exciting and disruptive technology. This review will focus on clinical trials related to TAVR that have been presented in the past year or are currently enrolling, as well as future trials that are in the planning stages.

RECENT FINDINGS

The currently available devices have gone through iterations to improve safety and outcomes, including lower profiles to reduce bleeding complications as well as adding a sealing skirt or allowing for re-positioning in order to decrease para-valvular regurgitation and need for a permanent pacemaker. The intermediate-risk clinical trials will be finishing soon and will be followed by low-risk trials. Ancillary devices will likely continue to expand the access to this therapy. One of the main challenges moving forward will be the post-TAVR pharmacotherapy.

SUMMARY

Recently, improvements in first-generation devices have led to improved outcomes. Current trials evaluating novel TAVR platforms and lower risk patients as well as ancillary devices will likely continue to expand the access to this therapy.

Heart valve health, disease, replacement, and repair: a 25-year cardiovascular pathology perspective

The past several decades have witnessed major advances in the understanding of the structure, function, and biology of native valves and the pathobiology and clinical management of valvular heart disease. These improvements have enabled earlier and more precise diagnosis, assessment of the proper timing of surgical and interventional procedures, improved prosthetic and biologic valve replacements and repairs, recognition of postoperative complications and their management, and the introduction of minimally invasive approaches that have enabled definitive and durable treatment for patients who were previously considered inoperable. This review summarizes the current state of our understanding of the mechanisms of heart valve health and disease arrived at through innovative research on the cell and molecular biology of valves, clinical and pathological features of the most frequent intrinsic structural diseases that affect the valves, and the status and pathological considerations in the technological advances in valvular surgery and interventions. The contributions of many cardiovascular pathologists and other scientists, engineers, and clinicians are emphasized, and potentially fruitful areas for research are highlighted.

Safety and Use of Anticoagulation After Aortic Valve Replacement With Bioprostheses: A Meta-Analysis

BACKGROUND

The American College of Cardiology guidelines recommend 3 months of anticoagulation after replacement of the aortic valve with a bioprosthesis. However, there remains great variability in the current clinical practice and conflicting results from clinical studies. To assist clinical decision making, we pooled the existing evidence to assess whether anticoagulation in the setting of a new bioprosthesis was associated with improved outcomes or greater risk of bleeding.

METHODS AND RESULTS

We searched the PubMed database from the inception of these databases until April 2015 to identify original studies (observational studies or clinical trials) that assessed anticoagulation with warfarin in comparison with either aspirin or no antiplatelet or anticoagulant therapy. We included the studies if their outcomes included thromboembolism or stroke/transient ischemic attacks and bleeding events. Quality assessment was performed in accordance with the Newland Ottawa Scale, and random effects analysis was used to pool the data from the available studies. I(2) testing was done to assess the heterogeneity of the included studies. After screening through 170 articles, a total of 13 studies (cases=6431; controls=18210) were included in the final analyses. The use of warfarin was associated with a significantly increased risk of overall bleeding (odds ratio, 1.96; 95% confidence interval, 1.25-3.08; P<0.0001) or bleeding risk at 3 months (odds ratio, 1.92; 95% confidence interval, 1.10-3.34; P<0.0001) compared with aspirin or placebo. With regard to composite primary outcome variables (risk of venous thromboembolism, stroke, or transient ischemic attack) at 3 months, no significant difference was seen with warfarin (odds ratio, 1.13; 95% confidence interval, 0.82-1.56; P=0.67). Moreover, anticoagulation was also not shown to improve outcomes at time interval >3 months (odds ratio, 1.12; 95% confidence interval, 0.80-1.58; P=0.79).

CONCLUSIONS

Contrary to the current guidelines, a meta-analysis of previous studies suggests that anticoagulation in the setting of an aortic bioprosthesis significantly increases bleeding risk without a favorable effect on thromboembolic events. Larger, randomized controlled studies should be performed to further guide this clinical practice.

The Effect of Valve-in-Valve Implantation Height on Sinus Flow

Valve-in-valve transcatheter aortic valve replacement (VIV-TAVR) has proven to be a successful treatment for high risk patients with failing aortic surgical bioprostheses. However, thrombus formation on the leaflets of the valve has emerged as a major issue in such procedures, posing a risk of restenosis, thromboembolism, and reduced durability. In this work we attempted to understand the effect of deployment position of the transcatheter heart valve (THV) on the spatio-temporal flow field within the sinus in VIV-TAVR. Experiments were performed in an in vitro pulsatile left heart simulator using high-speed Particle Image Velocimetry (PIV) to measure the flow field in the sinus region. The time-resolved velocity data was used to understand the qualitative and quantitative flow patterns. In addition, a particle tracking technique was used to evaluate relative thrombosis risk via sinus washout. The velocity data demonstrate that implantation position directly affects sinus flow patterns, leading to increased flow stagnation with increasing deployment height. The particle tracking simulations showed that implantation position directly affected washout time, with the highest implantation resulting in the least washout. These results clearly demonstrate the flow pattern and flow stagnation in the sinus is sensitive to THV position. It is, therefore, important for the interventional cardiologist and cardiac surgeon to consider how deployment position could impact flow stagnation during VIV-TAVR.

Variation in Warfarin Use at Hospital Discharge After Isolated Bioprosthetic Mitral Valve Replacement: An Analysis of the Society of Thoracic Surgeons Adult Cardiac Surgery Database

BACKGROUND

Anticoagulation with warfarin following bioprosthetic mitral valve replacement (BMVR) is recommended by multiple practice guidelines. We assessed practice variability and patient characteristics associated with warfarin prescription following BMVR.

METHODS

We analyzed 7,637 patients in the Society of Thoracic Surgeons Database (January 1, 2008 to June 30, 2011) who were discharged following isolated primary nonemergent BMVR. Patients requiring preoperative warfarin, those with preoperative atrial fibrillation, or those with a contraindication to warfarin were excluded. The association between patient, hospital, and surgeon characteristics and warfarin prescription were evaluated.

RESULTS

Fifty-eight percent of this cohort (median age, 66 years; female sex, 58.7%) was prescribed warfarin. Patients receiving warfarin were older (67 vs 65 years; P < .0001), were less likely to have had preoperative stroke (9.3% vs 12.1%; P < .001), CHF (51.4% vs 54.1%; P < .02), or dialysis (4.9% vs 9.0%; P < 0.001), and had a longer postoperative length of stay (8.0 vs 7.0 days; P < 0.01). Warfarin was prescribed less often for patients with postoperative GI events (44.4% vs 55.6%; P < .001) but more often for patients with postoperative myocardial infarction (75.8% vs 24.2%; P < .001) or new atrial fibrillation (68% vs 32%; P < .001) and those requiring blood transfusions intraoperatively (55.7% vs 44.3%; P < .001) or postoperatively (57% vs 43%; P < .03). Similar rates of warfarin prescription were observed in patients requiring reoperation for bleeding (54.9% vs 45.1%; P = .20) and those with postoperative stroke (53.6 % vs 46.4 %; P = .30). After adjusting for patient characteristics, significant surgeon and hospital variation in warfarin prescription at hospitals was observed.

CONCLUSIONS

Although patient characteristics and postoperative events may be associated with the prescription of warfarin following BMVR, substantial surgeon and hospital variability remains. This variability largely ignores the established practice guidelines and warrants further study to define the optimal anticoagulation strategy in patients undergoing BMVR.

Transcatheter or Surgical Aortic-Valve Replacement in Intermediate-Risk Patients

BACKGROUND

Previous trials have shown that among high-risk patients with aortic stenosis, survival rates are similar with transcatheter aortic-valve replacement (TAVR) and surgical aortic-valve replacement. We evaluated the two procedures in a randomized trial involving intermediate-risk patients.

METHODS

We randomly assigned 2032 intermediate-risk patients with severe aortic stenosis, at 57 centers, to undergo either TAVR or surgical replacement. The primary end point was death from any cause or disabling stroke at 2 years. The primary hypothesis was that TAVR would not be inferior to surgical replacement. Before randomization, patients were entered into one of two cohorts on the basis of clinical and imaging findings; 76.3% of the patients were included in the transfemoral-access cohort and 23.7% in the transthoracic-access cohort.

RESULTS

The rate of death from any cause or disabling stroke was similar in the TAVR group and the surgery group (P=0.001 for noninferiority). At 2 years, the Kaplan-Meier event rates were 19.3% in the TAVR group and 21.1% in the surgery group (hazard ratio in the TAVR group, 0.89; 95% confidence interval [CI], 0.73 to 1.09; P=0.25). In the transfemoral-access cohort, TAVR resulted in a lower rate of death or disabling stroke than surgery (hazard ratio, 0.79; 95% CI, 0.62 to 1.00; P=0.05), whereas in the transthoracic-access cohort, outcomes were similar in the two groups. TAVR resulted in larger aortic-valve areas than did surgery and also resulted in lower rates of acute kidney injury, severe bleeding, and new-onset atrial fibrillation; surgery resulted in fewer major vascular complications and less paravalvular aortic regurgitation.

CONCLUSIONS

In intermediate-risk patients, TAVR was similar to surgical aortic-valve replacement with respect to the primary end point of death or disabling stroke. (Funded by Edwards Lifesciences; PARTNER 2 ClinicalTrials.gov number, NCT01314313.).

In situ regeneration of bioactive coatings enabled by an evolved Staphylococcus aureus sortase A

Surface immobilization of bioactive molecules is a central paradigm in the design of implantable devices and biosensors with improved clinical performance capabilities. However, in vivo degradation or denaturation of surface constituents often limits the long-term performance of bioactive films. Here we demonstrate the capacity to repeatedly regenerate a covalently immobilized monomolecular thin film of bioactive molecules through a two-step stripping and recharging cycle. Reversible transpeptidation by a laboratory evolved Staphylococcus aureus sortase A (eSrtA) enabled the rapid immobilization of an anti-thrombogenic film in the presence of whole blood and permitted multiple cycles of film regeneration in vitro that preserved its biological activity. Moreover, eSrtA transpeptidation facilitated surface re-engineering of medical devices in situ after in vivo implantation through removal and restoration film constituents. These studies establish a rapid, orthogonal and reversible biochemical scheme to regenerate selective molecular constituents with the potential to extend the lifetime of bioactive films.

Bioactive coatings offer a strategy to modulate host response to implants, but their translation to the clinic is hampered by their fast in vivo degradation. Here, the authors use an engineered bacterial protein to regenerate an anti-thrombogenic film in vitro and in situ after device implantation.

Transcatheter Aortic Valve Implantation in Lower-Risk Patients With Aortic Stenosis

Transcatheter aortic valve implantation underwent progressive improvements until it became the default therapy for inoperable patients, and a recommended therapy in high-risk operable patients with symptomatic severe aortic stenosis. In the lower-risk patient strata, a currently costly therapy that still has important complications with questionable durability is competing with the established effective and still-improving surgical replacement. This report tries to weigh the clinical evidence, the recent technical improvements, the durability, and the cost-effectiveness claims supporting the adoption of transcatheter aortic valve implantation in intermediate-low risk patients. The importance of appropriate patients’ risk stratification and a more comprehensive approach to estimate that risk are also emphasized in the present report.

Management strategies and future challenges for aortic valve disease

The management of aortic valve disease has been improved by accurate diagnosis and assessment of severity by echocardiography and advanced imaging techniques, efforts to elicit symptoms or objective markers of disease severity and progression, and consideration of optimum timing of aortic valve replacement, even in elderly patients. Prevalence of calcific aortic stenosis is growing in ageing populations. Conventional surgery remains the most appropriate option for most patients who require aortic valve replacement, but the transcatheter approach is established for high-risk patients or poor candidates for surgery. The rapid growth of transcatheter aortic valve replacement has been fuelled by improved technology, evidence-based clinical research, and setting up of multidisciplinary heart teams. Aortic regurgitation can be difficult to diagnose and quantify. Left ventricular dysfunction often precedes symptoms, needing active surveillance by echocardiography to determine the optimum time for aortic valve replacement. Development of transcatheter approaches for aortic regurgitation is challenging, owing to the absence of valvular calcification and distortion of aortic root anatomy in many patients.

Noteworthy Literature in Cardiac Surgery 2015

In 2015, the cardiac literature has pushed for change in cardiac practice. The areas are evolving quickly based on new technology, ranging from percutaneous valves in the aortic position to mechanical support. The new devices in both these fields are changing the way patients are cared for very quickly. Another topic evolving is temperature management in aortic arch cases. This field is being pushed more by the threat of endovascular technology creeping into the arch than technology directly causing change in care. But that threat is real and inevitable. Finally, the discussion about optimal conduits is unending in coronary bypass grafting. A new algorithm has been proposed for utilization of more arterial grafts; however, there remains trepidation in changing from more vein grafts. Furthermore, those pushing for more arterial grafting seem to be black and white about these approaches rather than using what is best for the patient. These topics, among others, have made the literature from cardiac surgery in 2015 worth reading.

Update: Cardiac Imaging (II). Transcatheter Aortic Valve Replacement: Advantages and Limitations of Different Cardiac Imaging Techniques

Transcatheter aortic valve replacement is an established therapy for patients with symptomatic severe aortic stenosis and contraindications or high risk for surgery. Advances in prostheses and delivery system designs and continuous advances in multimodality imaging, particularly the 3-dimensional techniques, have led to improved outcomes with significant reductions in the incidence of frequent complications such as paravalvular aortic regurgitation. In addition, data on prosthesis durability are accumulating. Multimodality imaging plays a central role in the selection of patients who are candidates for transcatheter aortic valve replacement, procedure planning and guidance, and follow-up of prosthesis function. The strengths and limitations of each imaging technique for transcatheter aortic valve replacement will be discussed in this update article.

The Changing Paradigm in the Treatment of Structural Heart Disease and the Need for the Interventional Imaging Specialist

Percutaneous interventions in structural heart diseases are emerging rapidly. The variety of novel percutaneous treatment approaches and the increasing complexity of interventional procedures are associated with new challenges and demands on the imaging specialist. Standard catheterisation laboratory imaging modalities such as fluoroscopy and contrast ventriculography provide inadequate visualisation of the soft tissue or three-dimensional delineation of the heart. Consequently, additional advanced imaging technology is needed to diagnose and precisely identify structural heart diseases, to properly select patients for specific interventions and to support fluoroscopy in guiding procedures. As imaging expertise constitutes a key factor in the decision-making process and in the management of patients with structural heart disease, the sub-speciality of interventional imaging will likely develop out of an increased need for high-quality imaging.