Anatomical Characteristics Associated With Hypoattenuated Leaflet Thickening in Low-Risk Patients Undergoing Transcatheter Aortic Valve Replacement

Bioprosthetic Aortic Valve Thrombosis: Definitions, Clinical Impact, and Management: A State-of-the-Art Review

Bioprosthetic aortic valve thrombosis is frequently detected after transcatheter and surgical aortic valve replacement due to advances in cardiac computed tomography angiography technology and standardized surveillance protocols in low-surgical-risk transcatheter aortic valve replacement trials. However, evidence is limited concerning whether subclinical leaflet thrombosis leads to clinical adverse events or premature structural valve deterioration. Furthermore, there may be net harm in the form of bleeding from aggressive antithrombotic treatment in patients with subclinical leaflet thrombosis. This review will discuss the incidence, mechanisms, diagnosis, and optimal management of bioprosthetic aortic valve thrombosis after transcatheter aortic valve replacement and bioprosthetic surgical aortic valve replacement.

Commissural alignment and the ACURATE neo2 transcatheter aortic valve: Impact on valve performance

BACKGROUND

Transcatheter aortic valve replacement (TAVR) is increasingly being used to treat severe aortic stenosis in younger patients. Accordingly, lifetime management regarding future reintervention and coronary access is a concern.

AIMS

To assess the impact of commissural alignment on ACURATE neo2 transcatheter aortic valve (TAV) performance.

METHODS

COMALIGN-neo2 was an observational, retrospective study enrolling consecutive TAVR patients treated with the ACURATE neo2 (October 2021 to October 2022). The degree of commissural (mis)-alignment (CMA) with the native aortic valve commissures was determined and transvalvular gradient, effective orifice area, patient-prosthesis mismatch (PPM), and aortic regurgitation (AR) were assessed.

RESULTS

Among 825 patients, the mean age was 80.7 years and 42% were female. Commissural alignment was achieved in 60% of cases; mild (26%), moderate (9%), and severe misalignment (5%) were found less often. Severe PPM occurred more frequently in patients with severe CMA (14.7%) compared to aligned valves (p = 0.034). By multivariate analysis, severe CMA (odds ratio [OR]: 3.12, 95% confidence interval [CI] [1.09-8.90]; p = 0.033) and lack of postdilatation (OR: 3.85, [1.33-11.1]; p = 0.012) were associated with severe PPM. Higher rates of ≥mild AR (51.4%) were found in TAVs implanted with severe CMA compared to aligned (34.3%), mildly (38.1%) or moderately (36.0%) misaligned TAVs (p = 0.030). Multivariate analysis identified severe CMA (OR: 2.05, [1.05-4.02]; p = 0.037) to be an independent predictor of ≥mild AR.

CONCLUSIONS

COMALIGN-neo2 is the largest study to date assessing the impact of commissural alignment on acute TAV performance. Severe CMA with the ACURATE neo2 platform was associated with worse valve hemodynamics and increased risk for mild AR.

About different localization of hypoattenuated lesions following transcatheter aortic valve replacement

BACKGROUND

Subclinical leaflet thrombosis is diagnosed using multidetector computed tomography (MDCT) and is characterised by a meniscal-shaped hypoattenuated lesion of one or more leaflets. Transcatheter aortic self-expandable valves are commonly manufactured with pliable pericardium over a nitinol frame that forms leaflet and extra-leaflet components such as the valve skirt. Little is known about extra-leaflet hypoattenuated lesion localisation, including that at the anatomical sinus level. Thus, the main aim of this study was to describe leaflet and extra-leaflet (anatomic sinus and subvalvular level) hypoattenuated lesions following transcatheter aortic valve replacement with a self-expandable prosthesis. As a secondary aim, we sought to investigate predictors of hypoattenuated lesions.

METHODS

Fifty patients underwent MDCT at the follow-up.

RESULTS

At a follow-up of 12 months, hypoattenuated leaflet lesions with mild to severe restricted movement were detected in eight individuals (16%), anatomic sinus lesions were identified in nine patients (18%), with higher prevalence in the non-coronary sinus (16%), and subvalvular lesions with variable extension toward the valve inflow were diagnosed in eight patients (16%). In 4 patients (8%) the anatomic sinus thrombus was 'in overlap' with leaflet thrombus; in 3 patients (6%) was in continuity with subvalvular frame thrombus. Bicuspid valve was the only independent predictor associated with hypoattenuated lesions (adj OR 8.25 (95% CI: 1.38, 49.21), p = 0.02)).

CONCLUSIONS

This study demonstrated that hypoattenuated lesions could be identified not only at the leaflet but also at the subvalvular and anatomic sinus levels. The clinical relevance of such lesions remains unclear.

Evaluation of the anatomic sinus after transcatheter aortic valve replacement

BACKGROUND

Following transcatheter aortic valve replacement (TAVI), the newly formed 'anatomic sinus'. may contribute to the formation of subclinical leaflet thrombosis (SLT).The evaluation of root geometry after TAVI is generally performed using multi-detector computed tomography (MDCT), and the role of transthoracic echocardiography (2D TTE) requires further validation. Thus, we aimed to test the reproducibility of 2D TTE assessment of the anatomic sinus with MDCT as a reference and its association with SLT.

METHODS

2D TTE was performed in 90 patients, and the echocardiograms were analyzed offline. Both sinus of Valsalva (SOV) and prosthesis diameters were assessed in the long- and short-axis parasternal views (PLAX/PSAX), and the anatomic sinus area was calculated. Inter- and intra-observer reproducibility were assessed using the interclass correlation coefficient (ICC). MDCT was performed in 50 individuals to evaluate concordance with 2D TTE and to detect SLT.

RESULTS

There was excellent correlation regarding the diameter of the SOV and the prosthesis in PLAX (ICC: 0.93 (95% CI: 0.76,0.97); ICC: 0.80 (95% CI: 0.63,0.96)) and PSAX view (ICC: 0.90 (95% CI: 0.68,0.97); ICC: 0.88 (95% CI: 0.63,0.96)). Bland-Altman analysis of 2D TTE and MDCT anatomic sinus areas indicated a high level of agreement. SLT was detected in 8 individuals (16%); 3 patients had severe SLT at the level of 1 cusp.

CONCLUSIONS

2D TTE might play a role in the evaluation of the anatomic sinus after TAVI. The importance of this space and its effects on the SLT remain uncertain.

Commissural misalignment independently predicts leaflet thrombosis after transcatheter aortic valve implantation

AIMS

Transcatheter aortic valve implantation (TAVI) has become a minimally invasive alternative to surgical aortic valve replacement. Hypo-attenuated leaflet thickening (HALT)-a marker of subclinical leaflet thrombosis commonly detected by cardiac computed tomography (CT) after TAVI-may influence valve durability and function. The purpose of this study was to compare commissural alignment of the native and prosthetic aortic valves in cardiac CT in subjects with and without HALT and thereby identify commissural misalignment as potential predictor for leaflet thrombosis after TAVI.

METHODS AND RESULTS

In 170 subjects, 85 with and 85 without HALT in post-TAVI CT, commissural orientation of the prosthesis was determined comparing native and prosthetic aortic valve orientation in cardiac CT by measuring the commissural angle relative to the right coronary ostium in the aortic valve plane. For the prosthetic valve, any deviation ≤ 15° compared to the native valve was classified as "aligned"; 16-30° as "mild", 31-45° as "moderate" and ≥ 45° as "severe" misalignment. Among subjects with HALT, median angular deviation was higher (36°, IQR 31°) than in the control group (29°, IQR 29°, p = 0.042). "Severe" misalignment was more frequent in subjects who developed HALT (n = 31, 37%) compared to the control group (n = 17, 20%, p = 0.013). In logistic regression analysis, more severe deviation (p = 0.015, OR = 1.02 per 1° deviation) and "severe" misalignment (p = 0.018, OR = 2.2) represented independent predictors for the occurrence of HALT after TAVI.

CONCLUSION

Subclinical leaflet thrombosis after TAVI is associated with commissural misalignment. Potential clinical advantages of obtaining commissural alignment remain to be systematically assessed.

Self-Expandable Prosthesis Valve Adaptation: Non-Uniform Expansion and Stent Frame Decoupling

The incidence of non-uniform expansion in the context of the self-expandable transcatheter heart valve (THV) is little investigated, along with stent-frame decoupling, which is a form of stent adaptation, in which the lower part of the THV stent conforms to both the ellipticity of the left ventricle outflow tract and the native annulus while maintaining the higher part of the valve more circular. We analyzed post-implant multi-detector computed tomography scans in 50 patients. Prosthesis non-uniform expansion was assessed by computing the prosthesis eccentricity on 6 prespecified levels: (1) frame inflow, (2) native annulus, (3) leaflet inflow, (4) prosthesis waist, (5) leaflet outflow, and (6) frame outflow. Stent-frame decoupling was assessed by comparing the mean eccentricity on 6 different prosthesis levels. Implantation depth, leaflet expansion and alignment, and residual anatomic sinus area ratios were also calculated. Subclinical leaflet thrombosis was defined as hypoattenuated lesion of a meniscal shape. At a 12-month follow-up, non-uniform expansion was consistently detected at each valvular level. Highest eccentricity was measured at the native annulus level (eccentricity: 0.54 ±  0.12), while the lowest index at the frame outflow level (0.23 ± 0.11). Similar results were observed in the subgroup analyses of sizes 23, 26, 29, and 34. Eccentricity significantly decreased from the annulus level to the prosthesis frame outflow (p <0.001). Notably, the incidence of mild-to-severe subclinical leaflet thrombosis was relevant (16%). In conclusion, prosthesis non-uniform expansion and stent frame decoupling frequently occur after self-expandable THV replacement. The clinical and hemodynamic implications remain uncertain.

Subclinical Leaflet Thrombosis Following Surgical and Transcatheter Aortic Valve Replacement: A Meta-Analysis

Subclinical leaflets valve thrombosis (SLT) is a recently identified phenomenon with multidetector computer tomography after tissue aortic valve replacement. Whether SLT is more frequent after transcatheter aortic valve replacement (TAVR) or surgical aortic valve replacement (SAVR) is currently not known. Thus, the aim of this pairwise meta-analysis was to investigate the incidence of SLT after both TAVR and SAVR, the association with anticoagulation therapy, and the risk for neurological events. We searched PubMed, Google Scholar, and Ovid MEDLINE/Embase (January 02, 2023, last update) (PROSPERO registration: CRD42022383295). Statistical analysis was performed according to a prespecified statistical analysis plan. Time-to-event outcomes were summarized as incidence rate ratios (IRR). Pooled estimates were calculated using inverse variance method and random effect model. Overall, 2 registries, 2 randomized trials, and 1 observational study (1,593 patients) were included in this meta-analysis. There was a statistically significant difference in the incidence rate at follow-up of SLT between patients who underwent TAVR and SAVR (IRR 2.07, 95% confidence interval [CI]: [1.06; 4.03], I2 79%, 95% CI: [44; 92], p = 0.03). Oral anticoagulation therapy was associated with a reduced incidence of SLT (IRR 7.51, 95% CI: [3.24; 17.37], I2 62%, 95% CI: [0; 87], p <0.001). However, the incidence of later neurological events did not differ between patients with or without SLT (IRR 1.05, 95% CI: [0.32; 3.47], p = 0.93). In conclusion, SLT was more frequently detected after TAVR than SAVR. However, it was not associated with an increased risk for neurological events. Oral anticoagulation therapy seemed to reduce the incidence of SLT.

Transcatheter heart valve commissural alignment: an updated review

Transcatheter aortic valve replacement (TAVR) indications recently extended to lower surgical risk patients with longer life expectancy. Commissural alignment (CA) is one of the emerging concepts and is becoming one of the cornerstones of the TAVR procedure in a patient with increased longevity. Indeed, CA may improve transcatheter heart valve (THV) hemodynamics, future coronary access, and repeatability. The definition of CA has been recently standardized by the ALIGN-TAVR consortium using a four-tier scale based on CT analysis. Progress has been made during the index TAVR procedure to optimize CA, especially with self-expandable platforms. Indeed, specific delivery catheter orientation, THV rotation, and computed-tomography-derived views have been proposed to achieve a reasonable degree of CA. Recent data demonstrate feasibility, safety, and a significant reduction in coronary overlap using these techniques, especially with self-expandable platforms. This review provides an overview of THV CA including assessment methods, alignment techniques during the index TAVR procedure with different THV platforms, the clinical impact of commissural misalignment, and challenging situations for CA.

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.

Rationale, Definitions, Techniques, and Outcomes of Commissural Alignment in TAVR: From the ALIGN-TAVR Consortium

Given the expanding indications of transcatheter aortic valve replacement (TAVR) in younger patients with longer life expectancies, the ability to perform postprocedural coronary access represents a priority in their lifetime management. A growing body of evidence suggests that commissural (and perhaps coronary) alignment in TAVR impacts coronary access and valve hemodynamics as well as coronary flow and access after redo-TAVR. Recent studies have provided modified delivery system insertion and rotation techniques to obtain commissural alignment with available transcatheter heart valve devices. Moreover, patient-specific preprocedural planning and postprocedural imaging tools have been developed to facilitate and evaluate commissural alignment. Future efforts should aim to refine transcatheter heart valve and delivery system designs to make neocommissural alignment easier and more reproducible. The aim of this review is to present an in-depth insight of commissural alignment in TAVR, including its rationale, standardized definitions, technical steps, outcomes, and future directions.

Early Leaflet Thickening, Durability and Bioprosthetic Valve Failure in TAVR

All bioprosthetic valves, both surgical and transcatheter, have a finite lifespan before their leaflets inevitably degenerate, leading to stenosis or regurgitation. As younger, low-risk patients receive a transcatheter aortic valve, it is expected that they will most likely outlive their bioprosthetic valve. The heterogeneity of studies regarding surgical valve durability makes the interpretation of the data challenging. Leaflet thickening is seen in transcatheter heart valves but currently there is no evidence that it leads to premature valve deterioration or clinical events. Standardized definitions of structural valve deterioration should allow for comparisons between future clinical trials to assess the durability of different transcatheter heart valves.