Membranous septum morphology and risk of conduction abnormalities after transcatheter aortic valve implantation

Artificial Intelligence in the Screening, Diagnosis, and Management of Aortic Stenosis

The integration of artificial intelligence (AI) into clinical management of aortic stenosis (AS) has redefined our approach to the assessment and management of this heterogenous valvular heart disease (VHD). While the large-scale early detection of valvular conditions is limited by socioeconomic constraints, AI offers a cost-effective alternative solution for screening by utilizing conventional tools, including electrocardiograms and community-level auscultations, thereby facilitating early detection, prevention, and treatment of AS. Furthermore, AI sheds light on the varied nature of AS, once considered a uniform condition, allowing for more nuanced, data-driven risk assessments and treatment plans. This presents an opportunity to re-evaluate the complexity of AS and to refine treatment using data-driven risk stratification beyond traditional guidelines. AI can be used to support treatment decisions including device selection, procedural techniques, and follow-up surveillance of transcatheter aortic valve replacement (TAVR) in a reproducible manner. While recognizing notable AI achievements, it is important to remember that AI applications in AS still require collaboration with human expertise due to potential limitations such as its susceptibility to bias, and the critical nature of healthcare. This synergy underpins our optimistic view of AI's promising role in the AS clinical pathway.

Impact of new-onset arrhythmia on cardiac reverse remodeling following transcatheter aortic valve replacement: computed tomography-derived left ventricular and atrial strains

OBJECTIVE

Patients who undergo transcatheter aortic valve replacement (TAVR) are at risk for new-onset arrhythmia (NOA) that may require permanent pacemaker (PPM) implantation, resulting in decreased cardiac function. We aimed to investigate the factors that are associated with NOA after TAVR and to compare pre- and post-TAVR cardiac functions between patients with and without NOA using CT-derived strain analyses.

METHODS

We included consecutive patients who underwent pre- and post-TAVR cardiac CT scans six months after TAVR. New-onset left bundle branch block, atrioventricular block, and atrial fibrillation/flutter lasting over 30 days after the procedure and/or the need for PPM diagnosed within 1 year after TAVR were regarded as NOA. Implant depth and left heart function and strains were analyzed using multi-phase CT images and compared between patients with and without NOA.

RESULTS

Of 211 patients (41.7% men; median 81 years), 52 (24.6%) presented with NOA after TAVR, and 24 (11.4%) implanted PPM. Implant depth was significantly deeper in the NOA group than in the non-NOA group (- 6.7 ± 2.4 vs. - 5.6 ± 2.6 mm; p = 0.009). Left ventricular global longitudinal strain (LV GLS) and left atrial (LA) reservoir strain were significantly improved only in the non-NOA group (LV GLS,  - 15.5 ± 4.0 to  - 17.3 ± 2.9%; p < 0.001; LA reservoir strain, 22.3 ± 8.9 to 26.5 ± 7.6%; p < 0.001). The mean percent change of the LV GLS and LA reservoir strains was evident in the non-NOA group (p = 0.019 and p = 0.035, respectively).

CONCLUSIONS

A quarter of patients presented with NOA after TAVR. Deep implant depth on post-TAVR CT scans was associated with NOA. Patients with NOA after TAVR had impaired LV reserve remodeling assessed by CT-derived strains.

CLINICAL RELEVANCE STATEMENT

New-onset arrhythmia (NOA) following transcatheter aortic valve replacement (TAVR) impairs cardiac reverse remodeling. CT-derived strain analysis reveals that patients with NOA do not show improvement in left heart function and strains, highlighting the importance of managing NOA for optimal outcomes.

KEY POINTS

• New-onset arrhythmia following transcatheter aortic valve replacement (TAVR) is a concern that interferes with cardiac reverse remodeling. • Comparison of pre-and post-TAVR CT-derived left heart strain provides insight into the impaired cardiac reverse remodeling in patients with new-onset arrhythmia following TAVR. • The expected reverse remodeling was not observed in patients with new-onset arrhythmia following TAVR, given that CT-derived left heart function and strains did not improve.

Relationship between the aortic root and the atrioventricular conduction axis

Damage to the atrioventricular conduction axis continues to be a problem subsequent to transcatheter implantation of aortic valvar prostheses. Accurate knowledge of the precise relationships of the conduction axis relative to the aortic root could greatly reduce the risk of such problems. Current diagrams highlighting these relationships rightly focus on the membranous septum. The current depictions, however, overlook a potentially important relationship between the superior fascicle of the left bundle branch and the nadir of the semilunar hinge of the right coronary leaflet of the aortic valve. Recent histological investigations demonstrate, in many instances, a very close relationship between the left bundle branch and the right coronary aortic leaflet. The findings also highlight two additional variable features, which can be revealed by clinical imaging. The first of these is the extent of an inferoseptal recess of the left ventricular outflow tract. The second is the extent of rotation of the aortic root within the base of the left ventricle. Much more of the conduction axis is within the confines of the circumference of the outflow tract when the root is rotated in counterclockwise fashion as assessed from the perspective of the imager, with this finding itself associated with a much narrower inferoseptal recess. A clear understanding of the marked variability within the aortic root is key to avoiding future problems with atrioventricular conduction.

Anatomical mapping of the membranous septum in tricuspid and bicuspid aortic valves by cardiac computed tomography

A higher incidence of conduction disturbances and permanent pacemaker implantation (PPI) has been observed after transcatheter aortic valve implantation (TAVI) in patients with bicuspid aortic valves (BAVs) as compared to those with tricuspid aortic valves (TAVs). This study aimed to provide an anatomical explanation for this observation, supported by an in-depth anatomical mapping of the membranous septum (MS) in a large cohort of BAVs and TAVs using cardiac computed tomography (CT). A total of 300 cardiac CT scans were analysed, revealing a significantly shorter sub-annular length of the MS in BAVs at all measuring points compared to TAVs (p < 0.001). In the current BAV cohort, the MS was found to be at its shortest at the RCC site, measuring less than 1 mm in depth. In addition, the MS was located more anteriorly towards the RCC in BAVs, where the transcatheter aortic valve tends to be implanted deeper, and we observed a trend towards a higher PPI rate in BAVs. Future studies should investigate whether anatomical mapping of the MS in patients undergoing TAVI could be a useful tool for decision-making and potentially mitigate the risk of conduction disturbances.

Multi-modality imaging evaluation and pre-surgical planning for aortic valve-sparing operations in patients with aortic root aneurysm

Cardiac computed tomography (CT) and magnetic resonance (CMR) supplement echocardiography in the evaluation of those with aortic root and ascending aortic dilation, determining timing for intervention, guiding pre-surgical planning and post-operative surveillance. The dynamic, three-dimensional complexity of the aortic root and how it relates to the base of the left ventricle must be understood in any surgical approach addressing the aneurysmal aortic root. With improved imaging technology and the importance for proper patient counseling, it is no longer acceptable to enter the operating theater without a detailed blue print of what the problem is, and how best to address it. In addition, reliance on surgical expertise alone for intraoperative evaluation and decision making could be suboptimal due to the unloaded condition of the aortic root and the variance of experience of the surgeons to successfully repair the aortic valve. This is exemplified by the selective surgeons and centers who have the ability to tackle these aortic valve and root pathologies, compared to mitral valve repair techniques that have been codified and are generalizable. This review discusses a multimodality imaging approach in the patient with aortic root aneurysm, focusing on the precision added with pre-surgical CT assessment to guide aortic-valve sparing operations. This precision is afforded with a detailed understanding of the anatomy of the aortic root and underlying support, and its accurate evaluation by standard two- and three-dimensional imaging. Furthermore, we describe the evolving ability to predict the location of ventricular components of the atrioventricular conduction axis with further clinical imaging to personalize surgical strategies.

Transcatheter Aortic Valve Replacement Guided by Preprocedural Simulation of Fluoroscopic Location of the Membranous Septum

We show the virtual simulation of the fluoroscopic location of the membranous septum using preprocedural cardiac computed tomographic data sets. Recognizing the risk distance before the procedure can help individualize implantation strategy to reduce the risk of atrioventricular conduction axis damage during transcatheter aortic valve replacement. (Level of Difficulty: Advanced.).

Computed tomography-derived membranous septum length as predictor of conduction abnormalities and permanent pacemaker implantation after TAVI: A meta-analysis of observational studies

BACKGROUND

Permanent pacemaker implantation (PPI) after transcatheter aortic valve implantation (TAVI) is associated with higher risk of mortality and rehospitalization for heart failure. Efforts to prevent conduction abnormalities (CA) requiring PPI after TAVI should be made. The membranous septum (MS) length and its interaction with implantation depth (ID-ΔMSID) could provide useful information about the risk of CA/PPI following TAVI.

OBJECTIVES

To identify MS length and ΔMSID as predictors of CA/PPI following TAVI.

METHODS

Study-level meta-analysis of studies published by September 30, 2022.

RESULTS

Eighteen studies met our eligibility including 5740 patients. Shorter MS length was associated with a significantly higher risk of CA/PPI (per 1 mm decrease: odds ratio [OR] 1.60, 95% confidence interval [CI] 1.28-1.99, p < 0.001). Similarly, lower ΔMSID was associated with a significantly higher risk of CA/PPI (per 1 mm decrease: OR 1.75, 95% CI 1.32-2.31, p < 0.001). Meta-regression analyses revealed a statistically significant modulation of the effect of shorter MS length and lower ΔMSID on the outcome (CA/PPI) by balloon postdilatation (positive regression coefficients with p < 0.001); with increasing use of balloon postdilatation, the effect of shorter MS length and lower ΔMSID on the outcome increased. MS length and ΔMSID demonstrated excellent discriminative abilities, with diagnostic ORs equaling 9.49 (95% CI 4.73-19.06), and 7.19 (95% CI 3.31-15.60), respectively.

CONCLUSION

Considering that short MS length and low ΔMSID are associated with higher risk of CA and PPI, we should include measurement of MS length in the pre-TAVI planning with MDCT and try to establish optimal ID values before the procedure to avoid CA/PPI.

Vulnerability of the ventricular conduction axis during transcatheter aortic valvar implantation: A translational pathologic study

The ventricular components of the conduction axis remain vulnerable following transcatheter aortic valvar replacement. We aimed to describe features which may be used accurately by interventionalists to predict the precise location of the conduction axis, hoping better to avoid conduction disturbances. We scanned eight normal adult heart specimens by 3T magnetic resonance, using the images to simulate histological sections in order accurately to place the conduction axis back within the heart. We then used histology, tested in two pediatric hearts, to prepare sections, validated by the magnetic resonance images, to reveal the key relationships between the conduction axis and the aortic root. The axis was shown to have a close relationship to the nadir of the right coronary leaflet, in particular when the aortic root was rotated in counterclockwise fashion. The axis was more vulnerable in the setting of a narrow inferoseptal recess, when the inferior margin of the membranous septum was above the plane of the virtual basal ring, and when minimal myocardium was supporting the right coronary sinus. The features identified in our study are in keeping with the original description provided by Tawara, but at variance with more recent accounts. They suggest that the vulnerability of the axis during transcatheter valvar replacement can potentially be inferred on the basis of knowledge of the position of the aortic root within the ventricular base. If validated by clinical studies, our findings may better permit avoidance of new-onset left bundle branch block following transcatheter aortic valvar replacement.

Clinical and echocardiographic outcomes with new-onset left bundle branch block after SAPIEN-3 transcatheter aortic valve replacement

BACKGROUND

New-onset left bundle branch block (LBBB) can develop after transcatheter aortic valve replacement (TAVR) resulting in worse outcomes.

AIMS

Describe clinical and echocardiographic outcomes with new-onset LBBB after TAVR.

METHODS

We included consecutive patients who underwent transfemoral-TAVR with SAPIEN-3 (S3) valve between April 2015 and December 2018. Exclusion criteria included pre-existing LBBB, right BBB, left anterior hemiblock, left posterior hemiblock, wide QRS ≥ 120ms, prior permanent pacemaker (PPM), and nontransfemoral access.

RESULTS

Among 612 patients, 11.4% developed new-onset LBBB upon discharge. The length of stay was longer with new-onset LBBB compared with no LBBB [3 (2-5) days versus 2 (1-3) days; p < 0.001]. New-onset LBBB was associated with higher rates of 30-day PPM requirement (18.6% vs. 5.4%; p < 0.001) and 1-year heart failure hospitalizations (10.7% vs. 4.4%; p = 0.033). There was no difference in 3-year mortality between both groups (30.9% vs. 30.6%; p = 0.829). Further, new-onset LBBB was associated with lower left ventricular ejection fraction (LVEF) at both 30 days (55.9 ± 11.4% vs. 59.3 ± 9%; p = 0.026) and 1 year (55 ± 12% vs. 60.1 ± 8.9%; p = 0.002). These changes were still present when we stratified patients according to baseline LVEF (≥50% or <50%). New-onset LBBBs were associated with a higher 1-year LV end-diastolic volume index (51.4 ± 18.6 vs. 46.4 ± 15.1 ml/m² ; p = 0.036), and LV end-systolic volume index (23.2 ± 14.1 vs. 18.9 ± 9.7 ml/m² ; p = 0.009). Compared with resolved new-onset LBBB, persistent new-onset LBBB was associated with worse LVEF and higher PPM at 1 year.

CONCLUSIONS

New-onset LBBB after S3 TAVR was associated with higher PPM requirement, worse LVEF, higher LV volumes, and increased heart failure hospitalizations, with no difference in mortality.

Lifetime Management of Aortic Stenosis: Transcatheter Versus Surgical Treatment for Young and Low-Risk Patients

Transcatheter aortic valve replacement is now indicated across all risk categories of patients with symptomatic severe aortic stenosis and has been proposed as first line option for the majority of patients >74 years old. However, median age of patients enrolled in the transcatheter aortic valve replacement low-risk trials is 74 years and transcatheter aortic valve replacement has never been systematically investigated in young low risk patients. Although the long-term data in surgical aortic valve replacement in young patients (age <75) are well known, such data remain lacking in transcatheter aortic valve replacement. In the absence of clear guideline recommendations in patients with challenging anatomies (eg, hostile calcium, bicuspid), it is important to know the potential advantages and disadvantages of each treatment and to consider how they might integrate with each other in the lifetime management of such patients. In this review, we discuss current outstanding issues on the management of severe aortic stenosis from a lifetime management perspective, particularly in terms of initial intervention and future reinterventions.