Factors Determining Aortic Valve Dysfunction in Korean Subjects With a Bicuspid Aortic Valve

2023 Korean Society of Echocardiography position paper for diagnosis and management of valvular heart disease, part I: aortic valve disease

This manuscript represents the official position of the Korean Society of Echocardiography on valvular heart diseases. This position paper focuses on the clinical management of valvular heart diseases with reference to the guidelines recently published by the American College of Cardiology/American Heart Association and the European Society of Cardiology. The committee tried to reflect the recently published results on the topic of valvular heart diseases and Korean data by a systematic literature search based on validity and relevance. In part I of this article, we will review and discuss the current position of aortic valve disease in Korea.

Computed Tomography and Magnetic Resonance Imaging Findings of Bicuspid Aortic Valve and Related Abnormalities of the Heart and Thoracic Aorta

The bicuspid aortic valve (BAV) is the most common congenital cardiovascular malformation. Patients with BAV are at higher risk of other congenital cardiovascular malformations and valvular dysfunction, including aortic stenosis/regurgitation and infective endocarditis. BAV may also be related to aortic wall abnormalities such as aortic dilatation, aneurysm, and dissection. The morphology of the BAV varies with the presence and position of the raphe and is associated with the type of valvular dysfunction and aortopathy. Therefore, accurate diagnosis and effective treatment at an early stage are essential to prevent complications in patients with BAV. This pictorial essay highlights the characteristics of BAV and its related congenital cardiovascular malformations, valvular dysfunction, aortopathy, and other rare cardiac complications using multimodal imaging.

Aortic Valve Dysfunction and Aortopathy Based on the Presence of Raphe in Patients with Bicuspid Aortic Valve Disease

(1) Background: To identify the association between the presence or absence of a raphe and aortic valve dysfunction, as well as the presence of aortopathy in patients with a bicuspid aortic valve (BAV); (2) Methods: This retrospective study enrolled 312 participants (mean (SD) age, 52.7 (14.3) years; 227 men (72.8%)) with BAV. The BAVs were divided into those with the presence (raphe+) or absence (raphe-) of a raphe. Valvular function was classified as normal, aortic regurgitation (AR), or aortic stenosis (AS) using TTE. The pattern of BAV aortopathy was determined by the presence of dilatation at the sinus of Valsalva and the middle ascending aorta using CCT; (3) Results: BAVs with raphe+ had a higher prevalence of AR (148 (79.5%) vs. 48 (37.8%), p < 0.001), but a lower prevalence of AS (90 (48.6%) vs. 99 (78.0%), p < 0.001) compared with those with raphe-. The types of BAV aortopathy were significantly different (p = 0.021) according to those with BAV-raphe+ and BAV-raphe-; (4) Conclusions: The presence of a raphe was significantly associated with a higher prevalence of AR, but a lower prevalence of AS and combined dilatation of the aortic root and middle ascending aorta. The presence of a raphe was an independent determinant of AR.

Gender differences in bicuspid aortic valve Sievers types, valvulopathy, aortopathy, and outcome of aortic valve replacement

BACKGROUND

The gender difference of the bicuspid aortic valve (BAV) is not well understood.

OBJECTIVES

We evaluated the impact of gender on the Sievers types, valvulopathy, aortopathy, and outcomes of aortic valve replacement (AVR) of BAV patients in a cohort of Chinese patients.

METHODS

Among 992 BAV patients without aortic dissection nor congenital heart disease, 658 underwent AVR. The demography, Sievers types, valvulopathy, aortopathy, and outcomes of AVR were compared between genders.

RESULTS

Aortic regurgitation (AR ≥ 2+) (39.0% vs. 12.8%, p < .001), aortic root dilation only (3.8% vs. .8%, p = .014), and diffuse dilation (25.3% vs. 4.3%, p < .001) were more common in men, while moderate to severe aortic stenosis (AS) (21.3% vs. 45.7%, p < .001) and ascending dilation only (46.2% vs. 61.2%, p < .001) were more common in women. Men were more prone to develop preoperative AR ≥ 2+ (OR = 5.15, p < .001), moderate to severe AS + AR ≥ 2 + (OR = 2.95, p = .001), and Diffuse aortic dilation (OR = 3.91, p < .001). Sievers types did not have a significant effect on valvular dysfunction. Gender didn't predict early adverse events after AVR (n = 90) (HR = 1.21, p = .44), but male gender predicted a left ventricular ejection fraction <50% after AVR (OR = 3.07, p = .03).

CONCLUSIONS

In this BAV series of Chinese patients, gender didn't differ significantly in Sievers types of BAV but showed significant differences in valvulopathy, aortopathy, and LV function after AVR. In addition, the male patients developed more severe conditions at a younger age.

Unraveling Bicuspid Aortic Valve Enigmas by Multimodality Imaging: Clinical Implications

Multimodality imaging is the basis of the diagnosis, follow-up, and surgical management of bicuspid aortic valve (BAV) patients. Transthoracic echocardiography (TTE) is used in our clinical routine practice as a first line imaging for BAV diagnosis, valvular phenotyping and function, measurement of thoracic aorta, exclusion of other aortic malformations, and for the assessment of complications such are infective endocarditis and aortic. Nevertheless, TTE is less useful if we want to assess accurately other aortic segments such as mid-distal ascending aorta, where computed tomography (CT) and magnetic resonance (CMR) could improve the precision of aorta size measurement by multiplanar reconstructions. A major advantage of CT is its superior spatial resolution, which affords a better definition of valve morphology and calcification, accuracy, and reproducibility of ascending aorta size, and allows for coronary artery assessment. Moreover, CMR offers the opportunity of being able to evaluate aortic functional properties and blood flow patterns. In this setting, new developed sequences such as 4D-flow may provide new parameters to predict events during follow up. The integration of all multimodality information facilitates a comprehensive evaluation of morphologic and dynamic features, stratification of the risk, and therapy guidance of this cohort of patients.

Temporal Trends in Diagnosis, Treatments, and Outcomes in Patients With Bicuspid Aortic Valve

Background: The population is aging and advances in multimodal imaging and transcatheter valve intervention have been prominent in the past two decades. This study investigated temporal trends in demographic characteristics, use of multimodal imaging, treatments, and outcomes in patients with bicuspid aortic valve (BAV). Methods and Results: A total of 1,497 patients (male 71.7%, 57 ± 14 years old) first diagnosed with BAV between January 2003 and December 2020, in a single tertiary center were divided into three groups according to year of diagnosis: group 1 (2003-2008, n = 269), group 2 (2009-2014, n = 594), and group 3 (2015-2020, n = 634). The patients' demographic characteristics, comorbidities, BAV morphology, BAV function, BAV-related disease, use of multimodal diagnostic imaging, treatment modality for BAV, and clinical outcomes were compared among the three groups. The ages at diagnosis and at the time of surgery/intervention increased considerably from group 1 to 3. The patients' comorbidity index also increased progressively. The proportion of non-dysfunctional BAV and significant AS increased, while that of significant AR decreased. The frequency of infective endocarditis as an initial presentation significantly decreased over time. Additionally, the use of multimodal imaging increased markedly in the most recent group. The results also indicated increasing trends in the use of bioprosthetic valves and transcatheter aortic valve replacement. Overall and cardiovascular survival rates improved from group 1 to 3 (log rank p < 0.001). Conclusions: For the past two decades, remarkable temporal changes have occurred in patient characteristics, use of multimodal diagnostic imaging, choice of treatment modality, and clinical outcomes in patients with BAV.

Prognostic significance of myocardial fibrosis and CMR characteristics in bicuspid aortic valve with moderate and severe aortic insufficiency

OBJECTIVES

This study attempted to evaluate the characteristics and prognostic value of myocardial fibrosis (MF) in aortic insufficiency (AI) patients with bicuspid aortic valve (BAV) or tricuspid aortic valve (TAV) by cardiac magnetic resonance (CMR).

METHODS

A total of 314 adults with CMR-diagnosed AI were retrospectively retrieved. Of them, 166 patients with moderate or severe AI were included and divided into two groups: BAV group (N = 46) and a TAV group (N = 120). The presence and characteristics of MF were assessed with CMR. The patients were followed for adverse clinical events. The prognostic capability of the parameters was assessed using Cox regression model.

RESULTS

LV fibrosis was more common in the BAV group than in the TAV group (65.2% vs. 45.0%; p = 0.020). There was a strong association between BAV and MF even after adjusting for clinical and imaging variables (odds ratio: 3.57; p = 0.031). Kaplan-Meier analysis showed a higher rate of clinical adverse events in AI+BAV patients with MF during a median follow-up of 4.7 years. Multivariate Cox regression analysis showed that late gadolinium enhancement (LGE) was an independent predictor of clinical adverse outcome.

CONCLUSION

MF is more common in AI with BAV than with TAV and is a predictor of clinical adverse events.

KEY POINTS

• The presence and extent of late gadolinium enhancement of left ventricular were more common and severer in the bicuspid aortic valve group than in the tricuspid aortic valve group in aortic insufficiency patients. • Bicuspid aortic valve was an independent factor for myocardial fibrosis in aortic insufficiency patients. • Late gadolinium enhancement could be used as an independent predictor of adverse clinical events in this population.

Progression and Outcomes of Non-dysfunctional Bicuspid Aortic Valve: Longitudinal Data From a Large Korean Bicuspid Aortic Valve Registry

Background: Using echocardiographic surveillance, many patients are diagnosed with bicuspid aortic valve (BAV) without significant valve dysfunction. Limited data are available regarding the progression and outcomes of non-dysfunctional BAV.

Methods and Results: We investigated 1,307 BAV patients (984 male, mean age 56 years) diagnosed from Jan 2003 through Dec 2018 in a single tertiary center. Seven hundred sixty-one patients underwent follow-up echocardiography at ≥1 year post-diagnosis. Non-dysfunctional BAV was defined as BAV without moderate aortic stenosis (AS) or aortic regurgitation (AR). The presence of aortopathy was defined as an ascending aorta diameter >37mm. Progression to significant BAV dysfunction, progression to severe aortopathy (ascending aorta diameter ≥45mm), and incidence of valve or aorta operation were analyzed. One hundred eighty-seven (25%) patients showed non-dysfunctional BAV. Among them, 104 (56%) had mild AS or AR, and 81 (43%) had aortopathy at indexed echocardiography. At 6.0 ± 3.8 years post-diagnosis, 56 (29%) progressed to dysfunctional BAV, 28 (15%) progressed to severe aortopathy, 22 (12%) underwent valve operation, and 19 (10%) experienced aorta operation. Eighty-nine percent of patients with normal BAV function and 61% of patients with mild AS or AR maintained non-dysfunctional BAV. More patients with aortopathy progressed to severe aortopathy (35 vs. 0% without aortopathy, p < 0.001), with a higher incidence of aorta operation (21 vs. 2%, p < 0.001).

Conclusions: In patients with non-dysfunctional BAV, initial BAV function and degree of aorta dilatation might be important for progression and outcomes. Patients without any dysfunction or aortopathy tend to maintain good structure and function for 6 years.

Differences in Flow-Gradient Patterns Between Severe Bicuspid Aortic Stenosis and Severe Tricuspid Aortic Stenosis - Mechanistic Insight From Multimodal Imaging

BACKGROUND

We investigated the flow-gradient pattern characteristics and associated factors in severe bicuspid aortic stenosis (AS) compared with severe tricuspid AS.Methods and Results:A total of 252 patients with severe AS (115 bicuspid vs. 137 tricuspid) who underwent aortic valve (AV) replacement were retrospectively analyzed. Patients were classified into 4 groups according to stroke volume index and mean pressure gradient across the AV [normal-flow-high-gradient (NF-HG), low-flow-high-gradient, normal-flow-low-gradient, low-flow-low-gradient (LF-LG)]. In 89 patients who underwent cardiac computed tomography (CT), influential structural parameters of the left ventricular outflow tract (LVOT), AV and ascending aorta were assessed. Bicuspid AS was more likely to present a NF-HG pattern (83.5% vs. 64.2%, P<0.001), and significantly fewer presented a LF-LG pattern compared with tricuspid AS. In bicuspid AS, there was a significant mismatch between geometric orifice area (GOA) on CT planimetry and effective orifice area (EOA) calculated using the echocardiographic continuity equation. Bicuspid AS presented with a larger angle between the LVOT-AV and aorta. Multivariate analysis of bicuspid AS revealed that systemic arterial compliance (β=-0.350, P=0.031) and the LVOT-AV-aorta angle (β=-0.538, P=0.001), and stroke volume index (β=0.409, P=0.008) were associated with a discrepancy between GOA and EOA.

CONCLUSIONS

Flow-gradient patterns in bicuspid AS differ from those of tricuspid AS and are associated with the structural and functional characteristics of the aorta.

Prevalence, Characteristics, and Clinical Significance of Concomitant Cardiomyopathies in Subjects with Bicuspid Aortic Valves

PURPOSE

The present study aimed to investigate the prevalence, characteristics, and clinical significance of concomitant specific cardiomyopathies in subjects with bicuspid aortic valves (BAVs).

MATERIALS AND METHODS

A total of 1186 adults with BAV (850 males, mean age 56±14 years) at a single tertiary center were comprehensively reviewed. Left ventricular non-compaction, hypertrophic cardiomyopathy, and idiopathic dilated cardiomyopathy were confirmed when patients fulfilled current clinical and echocardiographic criteria. Clinical and echocardiographic characteristics, including comorbidities, heart failure presentation, BAV morphology, function, and aorta phenotypes, in BAV subjects with or without specific cardiomyopathies were compared.

RESULTS

Overall, 67 subjects (5.6%) had concomitant cardiomyopathies: 40 (3.4%) patients with left ventricular non-compaction, 17 (1.4%) with hypertrophic cardiomyopathy, and 10 (0.8%) with dilated cardiomyopathy. BAV subjects with hypertrophic cardiomyopathy had higher prevalences of diabetes mellitus and heart failure with preserved ejection fraction, and tended to have type 0 phenotype, while BAV subjects with dilated cardiomyopathy showed higher prevalences of chronic kidney disease and heart failure with reduced ejection fraction. BAV subjects with left ventricular non-compaction were significantly younger and predominantly male, and had greater BAV dysfunction and a higher prevalence of normal aorta shape. In multiple regression analysis, cardiomyopathy was independently associated with heart failure (odds ratio 2.795, 95% confidential interval 1.603-4.873, p<0.001) after controlling for confounding factors.

CONCLUSION

Concomitant cardiomyopathies were observed in 5.6% of subjects with BAV. A few different clinical and echocardiographic characteristics were found. The presence of cardiomyopathy was independently associated with heart failure.

Age- and Sex-Related Aortic Valve Dysfunction and Aortopathy Difference in Patients with Bicuspid Aortic Valve

Bicuspid aortic valve (BAV) is the most common congenital heart disease. Different distribution of valve dysfunction was found in patients with BAV in different age and sex groups, but related difference was not well established. The aim of our study is to investigate age- and sex-related clinical characteristics differences in patients with BAV.Six hundred twenty patients with BAV who had moderate or severe aortic valve dysfunction were included in the study. Basic clinical data and image data were recorded. Patients were classified into four different age groups: (A: ≤ 50 years old; B: 50-60 years old; C: 60-70 years old; D: > 70 years old). The sex-related clinical difference in different age groups was compared. Association between incidence of aortic valve dysfunction and age was evaluated.Male patients had more frequent aortic regurgitation (AR) in patients younger than 70 years old (A: 52.3% versus 20.0%, P = 0.012; B: 43.2% versus 17.8%, P < 0.001; C: 17.0 versus 2.6%, P = 0.002), whereas female patients were more likely to have aortic stenosis (AS) (A: 75.0% versus 34.1%, P = 0.001; B: 77.8% versus 37.0%, P < 0.001; C: 93.6% versus 69.8%, P < 0.001). Frequency of AR in male patients decreased with age, whereas frequency of AS increased. Trend test showed a significant difference in incidence of aortic valve dysfunction as age increased in male patients (AR, P < 0.001; AS, P < 0.001). No trend was found in female patients.Male patients with BAV present more often with moderate/severe AR at a young age, and the frequency of AR decreases with age. Female patients with BAV had more frequent AS at first presentation regardless of age.

GATA6 loss-of-function mutation contributes to congenital bicuspid aortic valve

Congenital bicuspid aortic valve (BAV), the most common form of birth defect in humans, is associated with substantial morbidity and mortality. Increasing evidence demonstrates that genetic risk factors play a key role in the pathogenesis of BAV. However, BAV is a genetically heterogeneous disease and the genetic determinants underpinning BAV in an overwhelming majority of patients remain unknown. In the present study, the coding exons and flanking introns of the GATA6 gene, which encodes a zinc-finger transcription factor essential for the normal development of the aortic valves, were sequenced in 152 unrelated patients with congenital BAV. The available relatives of a proband harboring an identified GATA6 mutation and 200 unrelated, ethnically matched healthy individuals used as controls were also genotyped for GATA6. The functional characteristics of the mutation were analyzed by using a dual-luciferase reporter assay system. As a result, a novel heterozygous GATA6 mutation, p.E386X, was identified in a family with BAV transmitted in an autosomal dominant mode. The nonsense mutation was absent in 400 control chromosomes. Biological assays revealed that the mutant GATA6 protein had no transcriptional activity compared with its wild-type counterpart. Furthermore, the mutation disrupted the synergistic transcriptional activation between GATA6 and GATA4, another transcription factor causally linked to BAV. In conclusion, this study firstly associates GATA6 loss-of-function mutation with enhanced susceptibility to familial BAV, which provides novel insight into the molecular mechanism of BAV, implying potential implications for genetic counseling and personalized management of BAV patients.