The silent and apparent neurological injury in transcatheter aortic valve implantation study (SANITY): concept, design and rationale

Prevalence of Neurovascular Microemboli After Transcatheter Aortic Valve Replacement

Background

Neurolotic sequelae after transcatheter aortic valve replacement (TAVR) can cause significant morbidity and mortality. Transcranial Doppler (TCD) imaging can show real-time high intensity transient signals (HITS), which reflect active microembolization. Although it is well known that intraprocedural microembolism occurs, it is not known if this embolic phenomenon continues in the postprocedural period. We investigated whether microemboli occur post-TAVR and whether we could determine any clinical, procedural, or echocardiographic predictors.

Methods

We evaluated HITS in 51 consecutive patients undergoing unprotected TAVR with low-, intermediate-, or high-risk Society of Thoracic Surgeons score. Patients were excluded if they did not have temporal windows for insonation of the middle cerebral artery or if they were not willing to participate. Primary outcomes of HITS 24 hours post-TAVR were observed using a Philips iU22 TCD. TCD was performed at 3 time points (pre-, peri-, and post-TAVR) for each patient, before, during, and 24 hours postprocedure.

Results

While no HITS were detected in any of the patients preoperatively, all patients had HITS during the procedure. Interestingly, 56.8% had HITS 24 hours post-TAVR. One patient with HITS post-TAVR had a stroke 48 hours after TAVR.

Conclusion

We observed a high prevalence of microemboli 24 hours post-TAVR. None of the predictors for intraprocedural microembolism seemed to play an important role for post-TAVR microemboli.

Association between Neuron-Specific Enolase, Memory Function, and Postoperative Delirium after Transfemoral Aortic Valve Replacement

INTRODUCTION

Although transfemoral aortic valve replacement (TAVR) is a safe treatment for elderly patients with severe aortic valve stenosis, postoperative microembolism has been described. In this secondary endpoint analysis of the POST-TAVR trial, we aimed to investigate whether changes in neuron-specific enolase (NSE)-a biomarker of neuronal damage-are associated with changes in memory function or postoperative delirium (POD).

MATERIALS AND METHODS

This was a prospective single-center study enrolling patients undergoing elective TAVR. Serum NSE was measured before and 24 h after TAVR. POD was diagnosed using CAM-ICU testing. Memory function was assessed before TAVR and before hospital discharge using the "Consortium to Establish a Registry for Alzheimer's Disease" (CERAD) word list and the digit span task (DST) implemented in "∆elta-App".

RESULTS

Subjects' median age was 82 years (25th to 75th percentile: 77.5-85.0), 42.6% of subjects were women. CERAD scores significantly increased from pre- to post-TAVR, with p < 0.001. POD occurred in 4.4% (6/135) of subjects at median 2 days after TAVR. After TAVR, NSE increased from a median of 1.85 ng/mL (1.30-2.53) to 2.37 ng/mL (1.69-3.07), p < 0.001. The median increase in NSE was 40.4% (13.1-138.0) in patients with POD versus 17.3% (3.3-43.4) in those without POD (p = 0.17).

CONCLUSIONS

Memory function improved after TAVR, likely due to learning effects, with no association to change in NSE. Patients with POD appear to have significantly higher postoperative levels of NSE compared to patients without POD after TAVR. This finding suggests that neuronal damage, as indicated by NSE elevation, may not significantly impair assessed memory function after TAVR.

App-based assessment of memory functions in patients after transfemoral aortic valve replacement

BACKGROUND

Transfemoral aortic valve replacement (TAVR) is the standard treatment for elderly patients with aortic valve stenosis. Although safe and well-established, there is a risk of intraprocedural hemodynamic instability and silent cerebral embolism, which can lead to a decline in neurocognitive function and dementia. In clinical practice, comprehensive cognitive testing is difficult to perform. AI-assisted digital applications may help to optimize diagnosis and monitoring.

METHODS

Neurocognitive function was assessed by validated psychometric tests using "∆elta -App", which uses artificial intelligence and computational linguistic methods for extraction and analysis. Memory function was assessed using the 'Consortium to Establish a Registry for Alzheimer's Disease' (CERAD) word list and digit span task (DST) before TAVR and before hospital discharge. The study is registered in the German Register of Clinical Trials (https://drks.de/search/de/trial/DRKS00020813).

RESULTS

From October 2020 until March 2022, 141 patients were enrolled at University Hospital Heart Centre Brandenburg. Mean age was 81 ± 6 years, 42.6% were women. Time between the pre- and post-interventional test was on average 6 ± 3 days. Memory function before TAVR was found to be below average in relation to age and educational level. The pre-post TAVR comparison showed significant improvements in the wordlist repeat, P < 0.001 and wordlist recall test of CERAD, P < 0.001. There were no changes in the digital span test.

CONCLUSIONS

Despite impaired preoperative memory function before TAVR, no global negative effect on memory function after TVAR was detected. The improvements shown in the word list test should be interpreted as usual learning effects in this task.

Valve Academic Research Consortium 3: updated endpoint definitions for aortic valve clinical research

Aims 

The Valve Academic Research Consortium (VARC), founded in 2010, was intended to (i) identify appropriate clinical endpoints and (ii) standardize definitions of these endpoints for transcatheter and surgical aortic valve clinical trials. Rapid evolution of the field, including the emergence of new complications, expanding clinical indications, and novel therapy strategies have mandated further refinement and expansion of these definitions to ensure clinical relevance. This document provides an update of the most appropriate clinical endpoint definitions to be used in the conduct of transcatheter and surgical aortic valve clinical research.

Methods and results 

Several years after the publication of the VARC-2 manuscript, an in-person meeting was held involving over 50 independent clinical experts representing several professional societies, academic research organizations, the US Food and Drug Administration (FDA), and industry representatives to (i) evaluate utilization of VARC endpoint definitions in clinical research, (ii) discuss the scope of this focused update, and (iii) review and revise specific clinical endpoint definitions. A writing committee of independent experts was convened and subsequently met to further address outstanding issues. There were ongoing discussions with FDA and many experts to develop a new classification schema for bioprosthetic valve dysfunction and failure. Overall, this multi-disciplinary process has resulted in important recommendations for data reporting, clinical research methods, and updated endpoint definitions. New definitions or modifications of existing definitions are being proposed for repeat hospitalizations, access site-related complications, bleeding events, conduction disturbances, cardiac structural complications, and bioprosthetic valve dysfunction and failure (including valve leaflet thickening and thrombosis). A more granular 5-class grading scheme for paravalvular regurgitation (PVR) is being proposed to help refine the assessment of PVR. Finally, more specific recommendations on quality-of-life assessments have been included, which have been targeted to specific clinical study designs.

Conclusions 

Acknowledging the dynamic and evolving nature of less-invasive aortic valve therapies, further refinements of clinical research processes are required. The adoption of these updated and newly proposed VARC-3 endpoints and definitions will ensure homogenous event reporting, accurate adjudication, and appropriate comparisons of clinical research studies involving devices and new therapeutic strategies.

Valve Academic Research Consortium 3: Updated Endpoint Definitions for Aortic Valve Clinical Research

AIMS

The Valve Academic Research Consortium (VARC), founded in 2010, was intended to (i) identify appropriate clinical endpoints and (ii) standardize definitions of these endpoints for transcatheter and surgical aortic valve clinical trials. Rapid evolution of the field, including the emergence of new complications, expanding clinical indications, and novel therapy strategies have mandated further refinement and expansion of these definitions to ensure clinical relevance. This document provides an update of the most appropriate clinical endpoint definitions to be used in the conduct of transcatheter and surgical aortic valve clinical research.

METHODS AND RESULTS

Several years after the publication of the VARC-2 manuscript, an in-person meeting was held involving over 50 independent clinical experts representing several professional societies, academic research organizations, the US Food and Drug Administration (FDA), and industry representatives to (i) evaluate utilization of VARC endpoint definitions in clinical research, (ii) discuss the scope of this focused update, and (iii) review and revise specific clinical endpoint definitions. A writing committee of independent experts was convened and subsequently met to further address outstanding issues. There were ongoing discussions with FDA and many experts to develop a new classification schema for bioprosthetic valve dysfunction and failure. Overall, this multi-disciplinary process has resulted in important recommendations for data reporting, clinical research methods, and updated endpoint definitions. New definitions or modifications of existing definitions are being proposed for repeat hospitalizations, access site-related complications, bleeding events, conduction disturbances, cardiac structural complications, and bioprosthetic valve dysfunction and failure (including valve leaflet thickening and thrombosis). A more granular 5-class grading scheme for paravalvular regurgitation (PVR) is being proposed to help refine the assessment of PVR. Finally, more specific recommendations on quality-of-life assessments have been included, which have been targeted to specific clinical study designs.

CONCLUSIONS

Acknowledging the dynamic and evolving nature of less-invasive aortic valve therapies, further refinements of clinical research processes are required. The adoption of these updated and newly proposed VARC-3 endpoints and definitions will ensure homogenous event reporting, accurate adjudication, and appropriate comparisons of clinical research studies involving devices and new therapeutic strategies.

The learning curve in transcatheter aortic valve implantation clinical studies: A systematic review

Background

Transcatheter aortic-valve implantation (TAVI) has become an essential alternative to surgical aortic-valve replacement in the treatment of symptomatic severe aortic stenosis, and this procedure requires technical expertise. The aim of this study was to identify prospective studies on TAVI from the past 10 years, and then to analyze the quality of information reported about the learning curve.

Materials and methods

A systematic review of articles published between 2007 and 2017 was performed using PubMed and the EMBASE database. Prospective studies regarding TAVI were included. The quality of information reported about the learning curve was evaluated using the following criteria: mention of the learning curve, the description of a roll-in phase, the involvement of a proctor, and the number of patients suggested to maintain skills.

Results

A total of sixty-eight studies met the selection criteria and were suitable for analysis. The learning curve was addressed in approximately half of the articles (n = 37, 54 percent). However, the roll-in period was mentioned by only eight studies (12 percent) and with very few details. Furthermore, a proctorship was disclosed in three articles (4 percent) whereas twenty-five studies (37 percent) included authors that were proctors for manufacturers of TAVI.

Conclusion

Many prospective studies on TAVI over the past 10 years mention learning curves as a core component of successful TAVI procedures. However, the quality of information reported about the learning curve is relatively poor, and uniform guidance on how to properly assess the learning curve is still missing.

Neuron-Specific Enolase and Matrix Metalloproteinase 9 Signal Perioperative Silent Brain Infarction During or After Transcatheter Aortic Valve Implantation

Magnetic resonance imaging (MRI) studies have consistently identified a high incidence of silent brain infarction (SBI) after cardiac intervention. The frequent occurrence, objective measurement and clinical sequelae of SBI have seen interest in their detection for both research and clinical purposes. However, MRI is expensive, time-consuming, unsafe in acutely-ill patients, and not always available, limiting its use as a routine screening tool. For this purpose, a blood biomarker of SBI would be the "Holy Grail." By performing targeted profiling of serologic biomarkers this study aimed to assess their potential as screening tools for perioperative SBI. This is a nested case-control study of 20 prospectively recruited patients undergoing transcatheter aortic valve implantation under general anesthesia. Clinical and diffusion-weighted MRI assessments were performed at baseline and on day 3 postprocedure to identify the presence (cases) or absence (controls) of new SBI. Blood was collected at baseline and 24, 48, and 72 hours postprocedure and analyzed for S100 calcium-binding protein B, neuron specific enolase (NSE), matrix metalloproteinase 9 (MMP 9), and glial fibrillary acidic protein. Best-fit polynomial curves using a smoothing model were generated for each biomarker and inferential testing at a predefined 24-hour postprocedure timepoint detected a significant difference for MMP 9 (72,435; SEM: 25,030; p = 0.027). Longitudinal regression revealed a statistically significant case-control difference for both NSE (mean: 10,747; SEM: 3,114) and MMP 9 (63,842; SEM: 16,173). In conclusion, NSE and MMP 9 are present in higher levels following SBI and warrant further investigation for their utility as screening tools.

Differential immunological profiles herald magnetic resonance imaging-defined perioperative cerebral infarction

Background:

The perioperative period is associated with a high risk for human ischaemic stroke. Although inflammatory mechanisms are known to have an important role in cerebral infarction in the nonoperative setting, their role in modulating perioperative risk remains unclear.

Methods:

In this prospective case-control study, we compared 10 patients (cases) who developed magnetic resonance imaging (MRI) evidence of cerebral infarction following transcatheter aortic valve implantation with 10 patients (controls) who underwent the same procedure without neurological complication. Blood sampling was performed preoperatively (baseline) and at 24 h, 48 h and 72 h postoperatively and analysed for specific cytokines, chemokines and complement factors.

Results:

Baseline serum assessments identified significant differences between the two cohorts for levels of complement C3, complement C4b, granulocyte-macrophage colony-stimulating factor, interleukin-15 and macrophage inflammatory protein-1β. Longitudinal regression analysis and best-fit polynomial curves of postoperative analyte profiles identified significantly higher levels of complement C3 and matrix metalloproteinase-9, and lower levels of interferon-γ and macrophage inflammatory protein-1β levels in cases versus controls.

Conclusions:

These results support a potentially important role for inflammatory mechanisms in MRI-defined perioperative stroke and reveal a potentially important role for complement components in this process.

Intraoperative Cerebral Perfusion Disturbances During Transcatheter Aortic Valve Replacement

BACKGROUND

Transcatheter aortic valve replacement entails profound and unavoidable hemodynamic perturbations that may contribute to the neurological injury associated with the procedure.

METHODS

Thirty-one patients were monitored with cerebral oximetry as a surrogate marker of perfusion while undergoing transcatheter aortic valve replacement via a transfemoral approach under general anesthesia to detect intraoperative hypoperfusion insult. Serial neurologic, cognitive, and cerebral magnetic resonance imaging assessments were administered to objectively quantify perioperative neurologic injury and ascertain any association with significant cerebral oximetry disturbances.

RESULTS

Cerebral oximetry reacted promptly to rapid ventricular pacing with significant cerebral desaturation, relative to baseline, of greater than 12% and greater than 20% in 12 of 31 (68%) and 9 of 31 (29%) patients, respectively; or to an absolute measurement of less than 50% in 10 of 31 (33%) patients. Hyperemia occurred immediately following relief of aortic stenosis exceeding baseline by greater than 10% and greater than 20% in 14 of 31 (45%) and 5 of 31 (16%) patients. Postoperative cognitive dysfunction was evident in 3 of 31 (10%) patients and new magnetic resonance imaging-defined ischemic lesions were seen in 17 of 28 (61%) patients. No patient experienced clinically apparent stroke.

CONCLUSIONS

Cerebral oximetry reacted promptly to rapid ventricular pacing with significant desaturation and hyperemia a common occurrence. However, no association between this intraoperative insult and objective neurologic injury was detected.

Aortic sinus flow stasis likely in valve-in-valve transcatheter aortic valve implantation

OBJECTIVE

Valve-in-valve procedures using transcatheter aortic valves are increasingly performed to treat degenerated bioprosthetic surgical aortic valves because they are less invasive than redo aortic valve replacement. The objective of this study is to quantify the changes in aortic sinus blood flow dynamics before and after a valve-in-valve procedure to gain insight into mechanisms for clinical and subclinical thrombosis of leaflets.

METHODS

A detailed description of the sinus hemodynamics for valve-in-valve implantation was performed in vitro. A Medtronic Hancock II (Medtronic Inc, Minneapolis, Minn) porcine bioprosthesis was modeled as a surgical aortic valve, and Medtronic CoreValve and Edwards Sapien (Edwards Lifesciences, Irvine, Calif) valves were used as the transcatheter aortic valves. High-resolution particle image velocimetry was used to compare the flow patterns from these 2 valves within both the left coronary and noncoronary sinuses in vitro.

RESULTS

Velocity and vorticity within the surgical valve sinuses reached peak values of 0.7 m/s and 1000 s^-1, with a 70% decrease in peak fluid shear stress near the aortic side of the leaflet in the noncoronary sinus. With the introduction of transcatheter aortic valves, peak velocity and vorticity were reduced to approximately 0.4 m/s and 550 s^-1 and 0.58 m/s and 653 s^-1 without coronary flow and 0.60 m/s and 631 s^-1 and 0.81 m/s and 669 s^-1 with coronary flow for the CoreValve and Sapien valve-in-valve implantations, respectively. Peak shear stress was approximately 38% higher along the aortic side of the coronary versus noncoronary transcatheter aortic valve leaflet.

CONCLUSIONS

Decreased flow and shear stress in valve-in-valve procedures indicate a higher risk of leaflet thrombosis secondary to flow stasis, perhaps more so in the noncoronary sinus.

Adjuncts to transcatheter aortic valve implantation

INTRODUCTION

The appreciable rise in percutaneous valve procedures has been pursued by a wave of development in advanced technology to help guide straightforward, streamlined and safe intervention. This review article aims to highlight the adjunctive devices, tools and techniques currently used in transcatheter aortic valve implantation procedures to avoid potential pitfalls. Areas covered: The software and devices featured here are at the forefront of technological advances, most of which are not yet in widespread use. These products have been discussed in national and international structural intervention conferences and the authors felt it important to showcase particularly well designed adjuncts that improve procedural efficacy and safety. Whilst vascular pre-closure systems are used routinely and are an integral part of these complex cardiovascular procedures, these have been well summarised elsewhere and are beyond the scope of this article. Expert commentary: The rising volume of patients with aortic stenosis who are treatable with TAVI means that this exponential increase in procedures must be accompanied by a steady decline in procedural complications. This section provides an overview of our current perspective, and what we feel the direction of travel will be.

Are anticoagulant independent mechanical valves within reach-fast prototype fabrication and in vitro testing of innovative bi-leaflet valve models

BACKGROUND

Exploration for causes of prosthetic valve thrombogenicity has frequently focused on forward or post-closure flow detail. In prior laboratory studies, we uncovered high amplitude flow velocities of short duration close to valve closure implying potential for substantial shear stress with subsequent initiation of blood coagulation pathways. This may be relevant to widely accepted clinical disparity between mechanical and tissue valves vis-à-vis thrombogenicity. With a series of prototype bi-leaflet mechanical valves, we attempt reduction of closure related velocities with the objective of identifying a prototype valve with thrombogenic potential similar to our tissue valve control. This iterative design approach may find application in preclinical assessment of valves for anticoagulation independence.

METHODS

Tested valves included: prototype mechanical bi-leaflet BVs (n=56), controls (n=2) and patented early prototype mechanicals (n=2) from other investigators. Pulsatile and quasi-steady flow systems were used for testing. Projected dynamic valve area (PDVA) was measured using previously described novel technology. Flow velocity over the open and closing periods was determined by volumetric flow rate/PDVA. For the closed valve interval, use was made of data obtained from quasi-steady back pressure/flow tests. Performance was ranked by a proposed thrombogenicity potential index (TPI) relative to tissue and mechanical control valves.

RESULTS

Optimization of the prototype valve designs lead to a 3-D printed model (BV3D). For the mitral/aortic site, BV3D has lower TPI (1.10/1.47) relative to the control mechanical valve (3.44/3.93) and similar to the control tissue valve (ideal TPI ≤1.0).

CONCLUSIONS

Using unique technology, rapid prototyping and thrombogenicity ranking, optimization of experimental valves for reduced thrombogenic potential was expedited and simplified. Innovative mechanical valve configurations were identified that merit consideration for further development which may bring the anti-coagulation independent mechanical valve within reach.

Total endoscopic sutureless aortic valve replacement: rationale, development, perspectives

Transcatheter valve implantation is progressively becoming the first line option for high risk patients in the management of severe aortic valve stenosis. Surgery is likely to remain the gold standard treatment option for intermediate risk patients since it ensures ablation of the underlying pathology and the calcified aortic valvular tissue, which potentially can act as a nidus of chronic embolization and provoke neurocognitive dysfunction in this subset of active patients. The surgical approach is continually evolving, with sutureless technology having the potential to facilitate ministernotomy and minithoracotomy approaches. Furthermore, Nitinol stented models can be introduced through thoracoscopic trocars, enabling the evolution of totally endoscopic aortic valve replacement (TEAVR). We present herein the development of TEAVR, starting from the cadaver experience in our lab. We transitioned through a clinical minithoracotomy video-assisted experience until we finally could initiate a program of human sutureless TEAVR. The limitations of this approach, which is still in refinement, and possible innovative solutions in order to build up a quick and reproducible procedure are discussed.

Nontransfemoral Approaches to Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement (TAVR) is noninferior to surgical aortic valve replacement in patients with high operative risk and superior to medical treatment in patients deemed unsuitable for surgical intervention. However, up to 30% to 50% of patients screened for this intervention are not candidates for TAVR via the preferred transfemoral route because of severe peripheral arterial disease. Alternative access routes must be considered and include the transapical, transaortic, transsubclavian, and transcarotid approaches. The use of alternative access is predicated on appropriate patient selection as determined by a dedicated multispecialty heart valve team and can lead to excellent outcomes.

The epidemiology of silent brain infarction: a systematic review of population-based cohorts

BACKGROUND

Cerebral infarction is a commonly observed radiological finding in the absence of corresponding, clinical symptomatology, the so-called silent brain infarction (SBI). SBIs are a relatively new consideration as improved imaging has facilitated recognition of their occurrence. However, the true incidence, prevalence and risk factors associated with SBI remain controversial.

METHODS

Systematic searches of the Medline and EMBASE databases from 1946 to December 2013 were performed to identify original studies of population-based adult cohorts derived from community surveys and routine health screening that reported the incidence and prevalence of magnetic resonance imaging (MRI)-determined SBI.

RESULTS

The prevalence of SBI ranges from 5% to 62% with most studies reported in the 10% to 20% range. Longitudinal studies suggest an annual incidence of between 2% and 4%. A strong association was seen to exist between epidemiological estimates of SBI and age of the population assessed. Hypertension, carotid stenosis, chronic kidney disease and metabolic syndrome all showed a strong association with SBI. Heart failure, coronary artery disease, hyperhomocysteinemia and obstructive sleep apnea are also likely of significance. However, any association between SBI and gender, ethnicity, tobacco or alcohol consumption, obesity, dyslipidemia, atrial fibrillation and diabetes mellitus remains unclear.

CONCLUSIONS

SBI is a remarkably common phenomenon and endemic among older people. This systematic review supports the association of a number of traditional vascular risk factors, but also highlights disparities between clinically apparent and silent strokes, potentially suggesting important differences in pathophysiology and warranting further investigation.