Effect of Aortic Valve Replacement on Aortic Root Dilatation Rate in Patients With Bicuspid and Tricuspid Aortic Valves

Bicuspid aortic valve disease: advancements and challenges of transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) has revolutionized the treatment of patients with severe aortic stenosis (AS). Initially developed for patients with tricuspid aortic valve (TAV) anatomy, the procedural success and expanding indications of TAVI have spurred interest in its application to more complex aortic valve anatomies, such as the bicuspid aortic valve (BAV). The growing interest in this specific sub-set of patients with AS is driven by the recent extension of TAVI indications to younger individuals, who exhibit a notably higher incidence of bicuspid anatomy compared with older populations. Bicuspid aortic valves present distinct anatomical and pathological complexities that pose significant challenges to the conventional TAVI approach. These include asymmetric calcification, aortic root dilation (also known as BAV aortopathy), and variations in cusp fusion patterns, which can affect valve deployment, transcatheter heart valve sealing, and long-term durability. Despite these challenges, advancements in imaging techniques, valve design, and procedural strategies have led to increased adoption of TAVI in BAV patients. However, surgical aortic valve replacement still retains a more prominent role in this group compared with patients with TAVs. This preference is partly due to the exclusion of BAV patients from almost all previous randomized controlled trials, which limits the available evidence supporting the use of TAVI in this unique cohort. This state-of-the-art review aims to provide a comprehensive overview of the current landscape of TAVI in BAV patients, including an analysis of anatomical considerations and procedural pitfalls, as well as outcomes' improvements with new device iterations. It will also explore clinical data, tackling the risks, benefits, and the evolving role of TAVI in this unique patient cohort.

Thoracic Aortic Aneurysm Growth Rates and Predicting Factors: A Systematic Review and Meta-Analysis

BACKGROUND

Thoracic aortic aneurysm (TAA) is an indolent, potentially fatal disease, which progresses at variable rates that are influenced by pathogenesis and patient characteristics. We conducted a systematic review and meta-analysis to synthesize the current evidence on growth rate (GR) and predictive factors among patients with syndromic and nonsyndromic heritable thoracic aortic disease, bicuspid aortic valve, and sporadic TAA.

METHODS AND RESULTS

Online databases were searched for studies that reported aortic growth on adult patients with asymptomatic TAA. Pooled GRs were calculated for 3 different TAA groups: syndromic heritable thoracic aortic disease, bicuspid aortic valve, and sporadic TAA. The search yielded 6297 studies, of which 85 were included in the systematic review, and 55 in the meta-analysis of growth rate (10 syndromic heritable thoracic aortic disease, 31 bicuspid aortic valve, and 34 sporadic subgroups). Mean observed TAA GR was 0.25 mm/y (95% CI, -0.18 to 0.68) in Turner syndrome, 0.45 mm/y (95% CI, 0.00-0.90) in Marfan syndrome, and 0.81 mm/y (95% CI, -0.46 to 2.08) in Loeys-Dietz syndrome. The mean observed GR in patients with bicuspid aortic valve before aortic valve surgery was 0.37 mm/y (95% CI, 0.29-0.46), compared with 0.18 mm/y (95% CI, 0.14-0.33) in postsurgical studies. Mean observed GR in sporadic ascending TAA was 0.33 mm/y (95% CI, 0.13-0.52) and 2.71 mm/y (95% CI, 0.53-4.88) in descending TAA.

CONCLUSIONS

Considering all pathogeneses, ascending TAAs typically grow at 0.25 to 1 mm/y, and thus annual surveillance is likely too frequent to detect growth in most patients. Studies vary widely in populations, methodology, and outcomes, with few high-quality longitudinal studies and no predictors of aortic GR.

Changes in aorta hemodynamics in Left-Right Type 1 bicuspid aortic valve patients after replacement with bioprosthetic valves: An in-silico study

Bicuspid aortic valve (BAV) is the most common cardiac congenital abnormality with a high rate of concomitant aortic valve and ascending aorta (AAo) pathologic changes throughout the patient's lifetime. The etiology of BAV-related aortopathy was historically believed to be genetic. However, recent studies theorize that adverse hemodynamics secondary to BAVs also contribute to aortopathy, but their precise role, specifically, that of wall shear stress (WSS) magnitude and directionality remains controversial. Moreover, the primary therapeutic option for BAV patients is aortic valve replacement (AVR), but the role of improved post-AVR hemodynamics on aortopathy progression is also not well-understood. To address these issues, this study employs a computational fluid dynamics model to simulate personalized AAo hemodynamics before and after TAVR for a small cohort of 6 Left-Right fused BAV patients. Regional distributions of five hemodynamic metrics, namely, time-averaged wall shear stress (TAWSS) and oscillating shear index (OSI), divergence of wall shear (DWSS), helicity flux integral & endothelial cell activation potential (ECAP), which are hypothesized to be associated with potential aortic injury are computed in the root, proximal and distal ascending aorta. BAVs are characterized by strong, eccentric jets, with peak velocities exceeding 4 m/s and axially circulating flow away from the jets. Such conditions result in focused WSS loading along jet attachment regions on the lumen boundary and weaker, oscillating WSS on other regions. The jet attachment regions also show alternating streaks of positive and negative DWSS, which may increase risk for local tissue stretching. Large WSS magnitudes, strong helical flows and circumferential WSS have been previously implicated in the progression of BAV aortopathy. Post-intervention hemodynamics exhibit weaker, less eccentric jets. Significant reductions are observed in flow helicity, TAWSS and DWSS in localized regions of the proximal AAo. On the other hand, OSI increases post-intervention and ECAP is observed to be low in both pre- and post-intervention scenarios, although significant increases are also observed in this ECAP. These results indicate a significant alleviation of pathological hemodynamics post AVR.

The Prevalence of Coronary Artery Disease in Bicuspid Aortic Valve Patients: An Overview of the Literature

The prevalence of coronary artery disease (CAD) in bicuspid aortic valve (BAV) patients is a debatable topic. Several studies have indicated that BAV patients have a lower prevalence of CAD compared with patients with a tricuspid aortic valve (TAV), but the effects of age and gender have not always been considered. This systematic review provides an overview of articles which report on CAD in BAV and TAV patients. Searches were executed in April 2021 and January 2022 according to the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-analyses) guidelines in three online databases: Medline, Embase, and Scopus. Screening and data extraction was done by two investigators separately. Primary and secondary outcomes were compared between BAV and TAV patients; a fixed effects model was used for correcting on confounders. Literature search yielded 1,529 articles with 44 being eligible for inclusion. BAV patients were younger (56.4 ± 8.3 years) than TAV patients (64 ± 10.3 years, p < 0.001). All CAD risk factors and CAD were more prevalent in TAV patients. No significant difference remained after correcting for age and gender as confounders. BAV patients have a lower prevalence of CAD and CAD risk factors compared with TAV patients. However, when the age differences between both groups are considered in the analyses, a similar prevalence of both CAD and CAD risk factors is found.

Aortic root replacement in the setting of a mildly dilated nonsyndromic ascending aorta

OBJECTIVE

There is controversy on how to address mild aortic root dilation during concomitant aortic valve replacement: composite aortic valve conduit replacement or separate ascending aorta and aortic valve replacement. We reviewed our experience to address the issue.

METHODS

We retrospectively reviewed 778 adult nonsyndromic patients with aortic root diameter 55 mm or less who received replacement of the ascending aorta and aortic valve from January 1994 to June 2017. Patients were divided into 2 groups based on the type of aortic root intervention: composite aortic valve conduit replacement in 406 patients (52%) and separate ascending aorta and aortic valve replacement in 372 patients (48%). Propensity matching was used to mitigate differences in baseline patient characteristics and produced 188 matched pairs.

RESULTS

Sinus of Valsalva diameter was 43 mm (39-47). Operative mortality occurred in 3 patients (2%) in the composite aortic valve conduit replacement group and in 5 patients (3%) in the separate ascending aorta and aortic valve replacement group (P = .470). Median follow-up was 9.6 years (8.4-10.1). Long-term mortality was similar in the 2 groups (P = .083). Repeat operation was performed in 13 patients (7%) in the composite aortic valve conduit replacement group and in 19 patients (10%) in the separate ascending aorta and aortic valve replacement group (P = .365). Sinus of Valsalva diameter decreased 2 mm (-4-0; median follow-up 41 months) in the propensity-matched separate ascending aorta and aortic valve replacement group.

CONCLUSIONS

In patients with mild aortic root dilation, separate ascending aorta and aortic valve replacement results in a similar risk of repeat operation and mortality in comparison with composite aortic valve replacement. Separate ascending aorta and aortic valve replacement is not associated with subsequent aortic root dilation on medium-term echocardiography follow-up.

Navigating the challenges of bicuspid aortic valve-aortopathy

Bicuspid aortic valve (BAV) is a congenital heart defect that affects 0.5-2% of the general population with familial predominance. The modifications in hemodynamics and structure change at cellular level contribute to the dilation of aorta, resulting in bicuspid aortopathy, which can result in catastrophic aortic events. The American Heart Association recommends screening first-degree relatives of patients with bicuspid aortic valve and aortic root disease. BAV may or may not be associated with a syndrome, with the non-syndromic variety having a higher chance of predisposition to congenital and vascular abnormalities. Many genes have been implicated in the etiology of non-syndromic aortic aneurysm such as ACTA2, MYH11, FLNA, and SMAD3. Common diagnostic modalities include transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), multi system computer tomography (MSCT), and cardiac MRI. Medical management reduces the rate of disease progression and surgical management is indicated based on the diameter of the ascending aorta, which differs in American and European guidelines. Our article aims to explore the current understanding of the pathophysiology, clinical aspects, and surgical management of bicuspid aortic valve disease. Additionally, we have included a discussion on the management of this condition in special populations, such as athletes and pregnant women, who require distinct treatment recommendations.

The Impact of Bicuspid Aortic Valve Leaflet Fusion Morphology on the Ascending Aorta and on Outcomes of Aortic Valve Replacement

BACKGROUND

Patients with bicuspid aortic valves (BAVs) tend to develop dilation of the ascending aorta. The aim of this study was to analyze the impact of leaflet fusion pattern on aortic root diameter and outcomes in patients undergoing surgery for BAV vs tricuspid aortic valve (TAV) disease.

METHODS

This is a retrospective review of 90 patients with aortic valve disease (mean [SD] age, 51.5 [8.2] years) who underwent aortic valve replacement for BAV (n = 60) and TAV (n = 30). Fusion of right-left (R/L) coronary cusps was identified in 45 patients, whereas the remaining 15 patients had right-noncoronary (R/N) cusp fusion. Aortic diameter was measured at 4 levels, and Z values were computed.

RESULTS

There were no significant differences between the BAV and TAV groups for age, weight, aortic insufficiency grade, or size of implanted prostheses. However, a higher preoperative peak gradient at the aortic valve was significantly associated with R/L fusion (P = .02). Preoperative Z values of ascending aorta and sinotubular junction diameter were significantly higher in patients with R/N fusion than with the R/L (P < .001 and P = .04, respectively) and TAV (P < .001 and P < .05, respectively) subgroups. During the follow-up period (mean [SD], 2.7 [1.8] years), 3 patients underwent a redo procedure. At the last follow-up, the sizes of ascending aorta were similar among all 3 patient groups.

CONCLUSION

This study suggests that preoperative dilation of the ascending aorta is more common in patients with R/N fusion than in patients with R/L and TAV but is not significantly different between all groups in the early follow-up period. R/L fusion was associated with an increased risk of preoperative presence of aortic stenosis.

Comparison of patients with bicuspid and tricuspid aortic valve in transcatheter aortic valve implantation

BACKGROUND

Transcatheter aortic valve implantation (TAVI) has emerged as a safe and effective alternative to surgery for aortic stenosis (AS). However, there are still differences in the procedural process and outcome of bicuspid aortic valve (BAV) treated with TAVI compared with tricuspid aortic valve.

AREAS COVERED

This review paper aims to summarize the main characteristics and clinical evidence of TAVI in patients with bicuspid and tricuspid aortic valves and compare the outcomes of TAVI procedure.

EXPERT OPINION

The use of TAVI in patients with BAV has shown similar clinical outcomes compared with tricuspid aortic valve. The efficacy of TAVI for challenging BAV anatomies remains a concern due to the lack of randomized trials. Detailed preprocedural planning is of great importance in low-surgical-risk BAV patients. A better understanding of which subtypes of BAV anatomy are at greater risk for adverse outcomes can potentially benefit the selection of TAVI or open-heart surgery in low surgical risk AS patients.

Changes of aortic hemodynamics after aortic valve replacement-A four dimensional flow cardiovascular magnetic resonance follow up study

Objectives

Non-invasive assessment of aortic hemodynamics using four dimensional (4D) flow magnetic resonance imaging (MRI) provides new information on blood flow patterns and wall shear stress (WSS). Aortic valve stenosis (AS) and/or bicuspid aortic valves (BAV) are associated with altered aortic flow patterns and elevated WSS. Aim of this study was to investigate changes in aortic hemodynamics over time in patients with AS and/or BAV with or without aortic valve replacement.

Methods

We rescheduled 20 patients for a second 4D flow MRI examination, whose first examination was at least 3 years prior. A total of 7 patients received an aortic valve replacement between baseline and follow up examination (=operated group = OP group). Aortic flow patterns (helicity/vorticity) were assessed using a semi-quantitative grading approach from 0 to 3, flow volumes were evaluated in 9 planes, WSS in 18 and peak velocity in 3 areas.

Results

While most patients had vortical and/or helical flow formations within the aorta, there was no significant change over time. Ascending aortic forward flow volumes were significantly lower in the OP group than in the NOP group at baseline (NOP 69.3 mL ± 14.2 mL vs. OP 55.3 mL ± 1.9 mL p = 0.029). WSS in the outer ascending aorta was significantly higher in the OP group than in the NOP group at baseline (NOP 0.6 ± 0.2 N/m² vs. OP 0.8 ± 0.2 N/m², p = 0.008). Peak velocity decreased from baseline to follow up in the aortic arch only in the OP group (1.6 ± 0.6 m/s vs. 1.2 ± 0.3 m/s, p = 0.018).

Conclusion

Aortic valve replacement influences aortic hemodynamics. The parameters improve after surgery.

Computed tomography follow-up after elective proximal aortic surgery: Less is more?

STUDY OBJECTIVE

The added value of computed tomography (CT) follow-up after elective proximal aortic surgery is unclear. We evaluated the benefit of CT follow-up by assessing the incidence of aorta-related complications and reinterventions detected during routine CT follow-up.

METHODS

Data on 314 patients undergoing first time elective proximal aortic surgery between 2000 and 2015 were collected. The primary study end points were aorta-related complications and reinterventions, detected during routine CT follow-up. Secondary study endpoints included all aorta-related complications and reinterventions, irrespective of the mode of detection and survival.

RESULTS

Median CT follow-up time was 6.8 (IQR 4.1-9.8) years, during which a total of 1303 routine follow-up CT-scans (median 4, IQR 3-5) were performed. During CT follow-up, aorta-related complications were detected in 18 (5.7%) patients, of which 6 (1.6%) underwent reintervention. In total, 28 aorta-related complications were observed in 23 (7.3%) patients, of which 9 led to reintervention. In order to detect 1 aorta-related complication leading to reintervention, 218 routine follow-up CT-scans were required. The unadjusted and EuroSCORE II adjusted hazard ratios of not undergoing CT follow-up on mortality were 1.260 (95% CI 0.705-2.251) and 0.830 (95% CI 0.430-1.605), respectively.

CONCLUSIONS

Following first time elective proximal aortic surgery, aorta-related complications are uncommon, are not always detected during CT follow-up and, if detected, often do not result in reintervention. Therefore, a more conservative CT follow-up protocol could be considered in selected patients to reduce lifetime radiation burden and health care costs.

Natural history and outcomes of non-replaced aortic sinuses in patients with bicuspid aortic valves

BACKGROUND

Enlargement of the sinus of Valsalva (SOV) is common in patients with bicuspid aortic valves (BAV), and management at the time of aortic valve replacement (AVR) and concomitant ascending aorta replacement/repair is controversial.

METHODS

Between January 2000 and July 2017, 400 patients with BAV underwent AVR and concomitant ascending aorta repair (79%, graft replacement; 21%, aortoplasty). To assess the impact of the initial SOV dimension on future dilatation and outcomes, patients were stratified into two groups: SOV<40mm (n=209) and SOV≥40mm (n=191).

RESULTS

Patients with SOV≥40 mm were older, and more often male. At a median follow-up of 8.1 years (IQR 7.4-9.1), 6 patients underwent reoperations on the ascending or sinus portion of the aorta due to aneurysmal dilatation; enlargement of the sinus was the primary indication for operation in one patient. Adjusted analysis showed that baseline SOV and SOV dimension over time were not associated with late outcomes. A gradual increase in SOV diameter over time was identified (P=0.004). Patients with smaller baseline SOV diameters showed an initial early decrease in diameter followed by gradual increase, while those with larger baseline diameters had a stable early phase followed by gradual dilatation.

CONCLUSIONS

Ascending aorta replacement may lead to an initial remodeling/stabilizing effect on the spared bicuspid aortic root, which is more pronounced in patients with lower SOV diameters. In addition, our data demonstrate that the retained aortic sinuses enlarge slowly, and within the limited follow-up of our study, SOV diameter was not a risk factor for survival or reoperation.

Hemodynamic Profiles Before and After Surgery in Bicuspid Aortic Valve Disease-A Systematic Review of the Literature

Bicuspid aortic valve (BAV) disease presents a unique management challenge both pre- and post-operatively. 4D flow MRI offers multiple tools for the assessment of the thoracic aorta in aortic valve disease. In particular, its assessment of flow patterns and wall shear stress have led to new understandings around the mechanisms of aneurysm development in BAV disease. Novel parameters have now been developed that have the potential to predict pathological aortic dilatation and may help to risk stratify BAV patients in future. This systematic review analyses the current 4D flow MRI literature after aortic valve and/or ascending aortic replacement in bicuspid aortic valve disease. 4D flow MRI has also identified distinct challenges posed by this cohort at the time of valve replacement compared to standard management of tri-leaflet disorders, and may help tailor the type and timing of replacement. Eccentric pathological flow patterns seen after bioprosthetic valve implantation, but not with mechanical prostheses, might be an important future consideration in intervention planning. 4D flow MRI also has promising potential in supporting the development of artificial valve prostheses and aortic conduits with more physiological flow patterns.

Outcome of reoperative aortic root or ascending aorta replacement after prior aortic valve replacement

Background

There are limited data regarding the clinical outcomes of reoperative aortic root or ascending aorta replacement after prior aortic valve replacement (AVR). We aimed to analyze outcomes of reoperative aortic root or ascending aorta replacement after prior AVR.

Methods

Eighty patients with prior AVR underwent reoperative aortic root or ascending aorta replacement in our hospital. The indications were root or ascending aortic aneurysm in 36 patients, root or ascending aortic dissection in 37, root false aneurysm in 2, prosthesis valve endocarditis (PVE) with root abscess in 2, Behçet’s disease (BD) with root destruction in 3 patients. An elective surgery was performed in 63 patients and an emergent surgery in 17. The survival and freedom from aortic events during the follow-up were evaluated with the Kaplan-Meier survival curve and the log-rank test.

Results

The operative techniques included ascending aorta replacement in 14 patients, ascending aorta replacement with AVR in 3, prosthesis-sparing root replacement (PSRR) in 35, Bentall procedure in 24, and Cabrol procedure in 4 patients. Operative mortality was 1.3% (1/80). A composite of adverse events occurred in 5 patients, including 1 operative death, 2 stroke and 3 renal failure necessitating hemodialysis. The mean follow-up was 35.5±22.1 months. Five late deaths occurred. The Kaplan-Meier survival at 1 year, 3 years and 6 years were 97.5%, 91.1% and 84.1%, respectively. Aortic events developed in 3 patients. The freedom from aortic events at 1-year, 3-year, and 6-year were 100%, 96.3% and 88.9%, respectively. There were no differences in survival and freedom from aortic events between the elective group and the emergent group.

Conclusions

Reoperative aortic root or ascending aorta replacement after prior AVR could be performed to treat the root or ascending pathologies after AVR, with satisfactory early and midterm outcomes.

Bicuspid Aortic Valve and Endothelial Dysfunction: Current Evidence and Potential Therapeutic Targets

Bicuspid aortic valve (BAV), the most frequent congenital heart malformation, is characterized by the presence of a two-leaflet aortic valve instead of a three-leaflet one. BAV disease progression is associated with valvular dysfunction (in the form of stenosis or regurgitation) and aortopathy, which can lead to aneurysm and aortic dissection. This morphological abnormality modifies valve dynamics and promotes eccentric blood flow, which gives rise to alterations of the flow pattern and wall shear stress (WSS) of the ascending aorta. Recently, evidence of endothelial dysfunction (ED) in BAV disease has emerged. Different studies have addressed a reduced endothelial functionality by analyzing various molecular biomarkers and cellular parameters in BAV patients. Some authors have found impaired functionality of circulating endothelial progenitors in these patients, associating it with valvular dysfunction and aortic dilation. Others focused on systemic endothelial function by measuring artery flow-mediated dilation (FMD), showing a reduced FMD in BAV individuals. Novel biomarkers like increased endothelial microparticles (EMP), which are related to ED, have also been discovered in BAV patients. Finally, latest studies indicate that in BAV, endothelial-to-mesenchymal transition (EndoMT) may also be de-regulated, which could be caused by genetic, hemodynamic alterations, or both. Different hypothesis about the pathology of ED in BAV are nowadays being debated. Some authors blamed this impaired functionality just on genetic abnormalities, which could lead to a pathological aorta. Nevertheless, thanks to the development of new and high-resolution imaging techniques like 4D flow MRI, hemodynamics has gained great attention. Based on latest studies, alterations in blood flow seem to cause proper modification of the endothelial cells (ECs) function and morphology. It also seems to be associated with aortic dilation and decreased vasodilators expression, like nitric oxide (NO). Although nowadays ED in BAV has been reported by many, it is not clear which its main cause may be. Comprehending the pathways that promote ED and its relevance in BAV could help further understand and maybe prevent the serious consequences of this disease. This review will discuss the ED present in BAV, focusing on the latest evidence, biomarkers for ED and potential therapeutic targets (Figure 1).

Long-term Fate of Dilated Ascending Aorta after Aortic Valve Replacement for Bicuspid Versus Tricuspid Aortic Valve Disease

We compared the long-term outcomes and difference in dilatation rates of the ascending aorta after aortic valve (AV) replacement (AVR) between bicuspid and tricuspid AV patients, and evaluated risk factors associated with ascending aorta dilatation and aortic events during the follow-up. Of 1,127 patients who underwent AVR from 1995 to 2015, 259 patients with a dilated ascending aorta (≥40 mm in diameter) were included. The patients were divided into those with bicuspid (group bicuspid aortic valve [BAV], n = 105) and with tricuspid (group tricuspid aortic valve [TAV], n = 154) AV, and a propensity score-matched analysis was performed to match 98 patients in each group. The differences in the dilation rate of the ascending aorta and long-term outcomes were analyzed. Risk factors for ascending aorta dilatation, mortality, and aortic events were identified. Follow-up was completed in 100% of patients with a median follow-up duration of 106.1 [68.8, 163.0] months. The early clinical outcomes and dilation rate of the ascending aorta were similar between the groups. Overall survivals up to 15 years postoperatively were similar between groups BAV and TAV (p = 0.223). Aortic events occurred in 6 patients (groups BAV vs TAV, 2 vs 4;p = 0.678). Preoperative ascending aorta diameter showed a linear relationship with the dilatation rate of ascending aorta (p <0.001) and was related to progressive aortic dilatation and aortic events (odds ratio: 1.25, p <0.001 and hazard ratio = 1.56, p <0.001, respectively). In conclusion, the long-term outcomes and ascending aorta dilatation rate were similar between the BAV and TAV patients up to 15 years after AVR. Bicuspid AV was not a risk factor of mortality or aortic events.

The American Association for Thoracic Surgery consensus guidelines on bicuspid aortic valve-related aortopathy: Full online-only version

Bicuspid aortic valve disease is the most common congenital cardiac disorder, being present in 1% to 2% of the general population. Associated aortopathy is a common finding in patients with bicuspid aortic valve disease, with thoracic aortic dilation noted in approximately 40% of patients in referral centers. Several previous consensus statements and guidelines have addressed the management of bicuspid aortic valve-associated aortopathy, but none focused entirely on this disease process. The current guidelines cover all major aspects of bicuspid aortic valve aortopathy, including natural history, phenotypic expression, histology and molecular pathomechanisms, imaging, indications for surgery, surveillance, and follow-up, and recommendations for future research. It is intended to provide clinicians with a current and comprehensive review of bicuspid aortic valve aortopathy and to guide the daily management of these complex patients.

The American Association for Thoracic Surgery consensus guidelines on bicuspid aortic valve-related aortopathy: Executive summary

Bicuspid aortic valve disease is a common congenital cardiac disorder, being present in 1% to 2% of the general population. Associated aortopathy is a common finding in patients with bicuspid aortic valve disease, with thoracic aortic dilation noted in approximately 40% of patients in referral centers. Several previous consensus statements and guidelines have addressed the management of bicuspid aortic valve-associated aortopathy, but none focused entirely on this disease process. The current document is an executive summary of "The American Association for Thoracic Surgery Guidelines on Bicuspid Aortic Valve-Related Aortopathy." All major aspects of bicuspid aortic valve aortopathy, including natural history, phenotypic expression, histology and molecular pathomechanisms, imaging, indications for surgery, surveillance, and follow-up, and recommendations for future research are contained within these guidelines. The current executive summary serves as a condensed version of the guidelines to provide clinicians with a current and comprehensive review of bicuspid aortic valve aortopathy and to guide the daily management of these complex patients.

Clinical-pathological correlations of BAV and the attendant thoracic aortopathies. Part 1: Pluridisciplinary perspective on their hemodynamics and morphomechanics

Clinical BAV manifestations pertain to faulty aortic valve (AOV) function, the associated aortopathy, and other complications such as endocarditis, thrombosis and thromboembolism. BAV arises during valvulogenesis when 2 of the 3 leaflets/cusps of the AOV are fused together. Ensuing asymmetric BAV morphologies alter downstream ejection jet flow-trajectories. Based on BAV morphologies, ejection-flows exhibit different wall-impingement and scouring patterns in the proximal aorta, with excessive hydrodynamic wall-shear that correlates closely with mural vascular smooth muscle cell and extracellular matrix disruptions, revealing hemodynamic participation in the pathogenesis of BAV-associated aortopathies. Since the embryologic regions implicated in both BAV and aortopathies derive from neural crest cells and second heart field cells, there may exist a common multifactorial/polygenic embryological basis linking the abnormalities. The use of Electronic Health Records - encompassing integrated NGS variant panels and phenotypic data - in clinical studies could speed-up comprehensive understanding of multifactorial genetic-phenotypic and environmental factor interactions. This Survey represents the first in a 2-article pluridisciplinary work. Taken in toto, the series covers hemodynamic/morphomechanical and environmental (milieu intérieur) aspects in Part 1, and molecular, genetic and associated epigenetic aspects in Part 2. Together, Parts 1-2 should serve as a reference-milestone and driver for further pluridisciplinary research and its urgent translations in the clinical setting.

Interval changes in aortic peak velocity and wall shear stress in patients with bicuspid aortic valve disease

Bicuspid aortic valve (BAV) is associated with abnormal valve-mediated hemodynamics including high velocity jets and elevated wall shear stress (WSS). This study investigated interval changes in flow and WSS in a multi-year follow-up study. This cross-sectional study included n = 44 patients with BAV (age = 44.9 ± 12 years), n = 17 patients with tricuspid aortic valve and thoracic aortic dilatation (TAV with dilation, age = 54.6 ± 16.5 years), and n = 9 healthy controls (age = 49.3 ± 14.7 years) underwent baseline and serial aortic 4D flow MRI (follow-up duration: BAV: 2.6 ± 0.7 years, TAV with dilation: 2.7 ± 0.5 years, controls: 1.1 ± 0.5 years). Data analysis included quantification of aortic dimensions, peak systolic velocities, as well as regional 3D WSS in the ascending aorta. At baseline, BAV patients demonstrated uniformly elevated peak velocity and WSS compared to TAV with dilation and control groups (peak velocity 2.2 m/s vs. 1.6 m/s vs. 1.5 m/s, p < 0.004; WSS: 0.74 Pa vs. 0.45 Pa vs. 0.55 Pa, p < 0.001). For BAV, peak velocity increased from baseline to follow up (2.2 ± 0.8 to 2.3 ± 0.9 m/s, p < 0.001) while WSS decreased (0.74 ± 0.22 to 0.65 ± 0.21 Pa, p < 0.001). Aortic growth was minimal for both BAV (0.05 cm/year) and TAV with dilation (0.03-0.04 cm/year) patients. For BAV patients, increase of ascending aorta peak velocities indicated worsening of valve function at follow-up. Compared to TAV with dilation patients, BAV patients demonstrated a reduction in WSS which may indicate a compensatory mechanism to reduce elevated WSS forces by aortic remodeling.

Ascending aortic dilatation rate after transcatheter aortic valve replacement in patients with bicuspid and tricuspid aortic stenosis: A multidetector computed tomography follow-up study

BACKGROUND

Current data is lacking about the progression of ascending aortic dilatation after transcatheter aortic valve replacement (TAVR) in aortic stenosis (AS) patients with bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV). This study aims to assess the ascending aortic dilatation rate (mm/year) after TAVR in patients with BAV versus TAV using a multidetector computed tomography (MDCT) follow-up and to determine the predictors of ascending aortic dilatation rate.

METHODS

Severe AS patients undergoing TAVR from March 2013 to March 2018 at our center with MDCT follow-ups were included. BAV and TAV were identified using baseline MDCT. Baseline and follow-up MDCT images were analyzed, and the diameters of ascending aorta were measured. Study end point is ascending aortic dilatation rate (mm/year). Furthermore, factors predicting ascending aortic dilatation rate were also investigated.

RESULTS

Two hundred and eight patients were included, comprised of 86 BAV and 122 TAV patients. Five, 4, 3, 2, and 1-year MDCT follow-ups were achieved in 7, 9, 30, 46, and 116 patients. The ascending aortic diameter was significantly increased after TAVR in both BAV group (43.7±4.4 mm vs. 44.0±4.5 mm; P<0.001) and TAV group (39.1±4.8 mm vs. 39.7±5.1 mm; P<0.001). However, no difference of ascending aortic dilatation rate was found between BAV and TAV group (0.2±0.8 mm/year vs. 0.3±0.8 mm/year, P=0.592). Multivariate linear regression revealed paravalvular leakage (PVL) grade was independently associated with ascending aortic dilatation rate in the whole population and BAV group, but not TAV group. No aortic events occurred during follow-ups.

CONCLUSION

Ascending aortic size continues to grow after TAVR in BAV patients, but the dilatation rate is mild and comparable to that of TAV patients. PVL grade is associated with ascending aortic dilatation rate in BAV patients post-TAVR.

The aortic root does not dilate over time after replacement of the aortic valve and ascending aorta in patients with bicuspid or tricuspid aortic valves

OBJECTIVE

Whether the aortopathy associated with bicuspid aortic valve (BAV) disease occurs secondary to genetic or hemodynamic factors remains controversial. In this article we describe the natural history of the aortic root in patients with bicuspid versus tricuspid aortic valves (TAVs) after replacement of the aortic valve and ascending aorta.

METHODS

From 1990 to 2010, 406 patients (269 BAV, 137 TAV) underwent aortic valve and ascending aorta replacement at a single institution. Patients with aortic dissection, endocarditis, previous aortic surgery, or Marfan syndrome were excluded. All available follow-up imaging was reviewed.

RESULTS

Mean imaging follow-up was 5.5 (±5.3) years. Of all patients, 66.5% had at least 1 aortic root measurement after the index operation. Baseline aortic diameter was comparable between groups. In patients with BAV, aortic root diameter increased at a clinically negligible rate over time (0.654 mm per year; 95% confidence interval, 0.291-1.016; P < .001), similar to patients with TAV (P = .92). Mean clinical follow-up was 8.1 (±5.4) years. During follow-up, 18 patients underwent reoperation, 89% for a degenerated bioprosthetic aortic valve. Only 1 patient underwent reoperation for a primary indication of aortic aneurysmal disease, 22 years after the index operation. There were no differences in cumulative incidence rates of aortic reoperation (P = .14) between patients with BAV and TAV.

CONCLUSIONS

Mid-term imaging after aortic valve and ascending aorta replacement indicates that if the aortic root is not dilated at the time of surgery, the risk of enlargement over time is minimal, negating the need for prophylactic root replacement in patients with BAV or TAV.

Pathogenic Mechanisms of Bicuspid Aortic Valve Aortopathy

Bicuspid aortic valve (BAV) is the most common congenital valvular defect and is associated with ascending aortic dilation (AAD) in a quarter of patients. AAD has been ascribed both to the hemodynamic consequences of normally functioning and abnormal BAV morphology, and to the effect of rare and common genetic variation upon function of the ascending aortic media. AAD manifests in two overall and sometimes overlapping phenotypes: that of aortic root aneurysm, similar to the AAD of Marfan syndrome; and that of tubular AAD, similar to the AAD seen with tricuspid aortic valves (TAVs). These aortic phenotypes appear to be independent of BAV phenotype, have different embryologic origins and have unique etiologic factors, notably, regarding the role of hemodynamic changes inherent to the BAV phenotype. Further, in contrast to Marfan syndrome, the AAD seen with BAV is infrequently present as a strongly inherited syndromic phenotype; rather, it appears to be a less-penetrant, milder phenotype. Both reduced levels of normally functioning transcriptional proteins and structurally abnormal proteins have been observed in aneurysmal aortic media. We provide evidence that aortic root AAD has a stronger genetic etiology, sometimes related to identified common non-coding fibrillin-1 (FBN1) variants and other aortic wall protein variants in patients with BAV. In patients with BAV having tubular AAD, we propose a stronger hemodynamic influence, but with pathology still based on a functional deficit of the aortic media, of genetic or epigenetic etiology. Although it is an attractive hypothesis to ascribe common mechanisms to BAV and AAD, thus far the genetic etiologies of AAD have not been associated to the genetic etiologies of BAV, notably, not including BAV variants in NOTCH1 and GATA4.