Bicuspid aortic valve: unresolved issues and role of imaging specialists

Diagnostic Performance of Cardiac CT and Transthoracic Echocardiography for Detection of Surgically Confirmed Bicuspid Aortic Valve: Effect of Calcium Extent and Valve Subtypes

Purpose

This study aimed to compare the diagnostic performance of cardiac CT and transthoracic echocardiogram (TTE) depending on the degree of valvular calcification and bicuspid aortic valve (BAV) subtype.

Materials and Methods

This retrospective study included 266 consecutive patients (106 with BAV and 160 with tricuspid aortic valve) who underwent cardiac CT and TTE before aortic valve replacement. Cardiac CT was used to evaluate the morphology of the aortic valve, and a calcium scoring scan was used to quantify valve calcium. The aortic valves were classified into fused and two-sinus types. The diagnostic accuracy of cardiac CT and TTE was calculated using a reference standard for intraoperative inspection.

Results

CT demonstrated significantly higher sensitivity, negative predictive value, and accuracy than TTE in detecting BAV (p < 0.001, p < 0.001, and p = 0.003, respectively). The TTE sensitivity tended to decrease as valvular calcification increased. The error rate of TTE for CT was 10.9% for the two-sinus type of BAV and 28.3% for the fused type (p = 0.044).

Conclusion

Cardiac CT had a higher diagnostic performance in detecting BAV than TTE and may help diagnose BAV, particularly in patients with severe valvular calcification.

Risk Factors Associated with Ascending Aortic Aneurysms and Aortic Elasticity Parameters in Children with a Bicuspid Aortic Valve

Aneurysms of the ascending aorta are frequently found in patients with a bicuspid aortic valve (BAV). This study assessed the risk factors of ascending aortic aneurysms and aortic elasticity in children with BAV. The study included 66 patients with no history of transcatheter intervention or surgical procedure who had been diagnosed with isolated BAV. Echocardiographic, blood pressure, and pulse measurements were obtained for all patients. The BAVs were classified as described by Sievers et al. (J Thorac Cardiovasc Surg 133:1226-1233, 2007), and aortic elasticity parameters were calculated using various formulas. The patients were divided into groups with and without cusp fusion, aortic stenosis (AS), aortic regurgitation (AR), or mixed lesions; the groups were then compared. The mean patient age was 10.43 ± 3.91 years; 15%he patients had no AS or AR, 33% had both AS and AR, 17% had AS alone, and 35% had AR alone. The most common type of BAV was type 5, and the ascending aorta z-scores were higher in children with mixed lesions and without a cusp fusion. Aortic distensibility (AD) was significantly higher, and the stiffness index was significantly lower, in patients with an ascending aorta z-score > 4. The ascending aortic z-scores were higher in the no-fusion and mixed lesion (AS + AR) groups, especially those originating from post-stenotic dilation due to AS. The AD was increased in patients with an ascending aorta z-score > 4. Patients should thus be monitored closely for dissection risk, and preventive medical treatment should be started early in those with AS without cusp fusion.

Misclassification of bicuspid aortic valves is common and varies by imaging modality and patient characteristics

BACKGROUND

Bicuspid aortic valve (BAV) is the most prevalent adult congenital heart defect. BAV causes lifelong progressive disease that can be prevented by early diagnosis and long-term surveillance, but may be compromised by misclassification of valve morphology.

METHODS

The study population was derived from the UTHealth Bicuspid Aortic Valve Registry, which includes serial images on more than 200 participants over a mean follow-up interval of 2.8 years. We abstracted descriptions of aortic valve morphology from transthoracic or transesophageal echocardiography, computed tomography angiography, and magnetic resonance angiography reports. We used chi-square and t tests to determine associations between reported valve morphologies (definitely bicuspid, possibly bicuspid, tricuspid, or uncertain) and clinical characteristics and assessed image quality using a validated tool.

RESULTS

About 40% of participants were misclassified in at least one imaging report. The mean interval between misclassification and correct diagnosis was 22 months. TEE, MR and CT were more sensitive than TTE and successfully reclassified 20% of participants, but were only used in 14% of patients. Misclassification was associated with age, the extent of valve calcification and image quality, but was not significantly associated with aortic regurgitation, gender, or cusp configuration.

CONCLUSION

Misclassification of BAV is prevalent, frequently leads to delayed diagnosis, and is more likely to occur in the most severely affected cases. TEE, CT and MR may increase diagnostic accuracy in up to half of BAV cases but are underutilized. Additional studies are needed to determine if misclassification of BAV patients leads to increased long-term morbidity and mortality.

Mid-term Clinical Outcomes in a Cohort of Asymptomatic or Mildly Symptomatic Korean Patients with Bicuspid Aortic Valve in a Tertiary Referral Hospital

BACKGROUND

Although bicuspid aortic valve (BAV) is one of the most common congenital heart diseases, clinical outcome data regarding BAV are still limited. We evaluated clinical characteristics and mid-term clinical outcomes of asymptomatic Korean patients with bicuspid aortic valve.

METHODS

We initiated a prospective registry in 2014 at a tertiary referral hospital. To develop a cohort of asymptomatic patients, we excluded patients who previously underwent open heart surgery (OHS) or who had OHS within 6 months of referral.

RESULTS

A total of 170 patients (117 male [69%], age 50 ± 13 years) were enrolled. More than 70% (n = 124, 73%) were incidentally diagnosed with BAV during routine health examinations or preoperative screening for non-cardiac surgery. At the time of enrollment, moderate to severe aortic stenosis (AS) or regurgitation (AR) was present in 77 patients (45%) and 98 (58%) showed aortic dilation: 42 (25%) had non-significant valvular dysfunction without aortic dilation. During a median follow-up of 4 years, AS severity increased significantly (p < 0.001), while there was no significant change in AR severity (p = 0.361). A total of 27 patients (16%) underwent OHS, including isolated aortic valve (AV) surgery (n = 11, 41%), AV with combined aortic surgery (n = 12, 44%), and isolated aortic surgery (n = 4, 15%): no patient developed aortic dissection. Moderate to severe AS (hazard ratio [HR] 4.61; 95% confidence interval [CI] 1.83-11.62; p = 0.001), NYHA class ≥ 2 (HR 2.53; 95% CI 1.01-6.35; p = 0.048) and aortic dilation (HR 2.13; 95% CI 0.87-5.21; p = 0.099) were associated with surgical events.

CONCLUSIONS

Progression patterns of valvular dysfunction and impacts of BAV phenotype on OHS should be explored in future studies with longer follow-up durations.

Evolution of Precision Medicine and Surgical Strategies for Bicuspid Aortic Valve-Associated Aortopathy

Bicuspid aortic valve (BAV) is a common congenital cardiac malformation affecting 1–2% of people. BAV results from fusion of two adjacent aortic valve cusps, and is associated with dilatation of the aorta, known as bicuspid valve associated aortopathy. Bicuspid valve aortopathy is progressive and associated with catastrophic clinical events, such as aortic dissection and rupture. Therefore, frequent monitoring and early intervention with prophylactic surgical resection of the proximal aorta is often recommended. However, the specific pattern of aortopathy is highly variable among patients, with different segments of the ascending aorta being affected. Individual patient risks are sometimes difficult to predict. Resection strategies are informed by current surgical guidelines which are primarily based on aortic size and growth criteria. These criteria may not optimally reflect the risk of important aortic events. To address these issues in the care of patients with bicuspid valve aortopathy, our translational research group has focused on validating use of novel imaging techniques to establish non-invasive hemodynamic biomarkers for risk-stratifying BAV patients. In this article, we review recent efforts, successes, and ongoing challenges in the development of more precise and individualized surgical approaches for patients with bicuspid aortic valves and associated aortic disease.

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

Bicuspid aortic valve (BAV) disease has a male predominance of approximately 3:1 and shows diverse presentations about aortic valve dysfunction. This study aimed to find independent determinants for significant aortic stenosis (AS) or significant aortic regurgitation (AR) in adults with BAV. We retrospectively investigated the medical records of 1,073 subjects (773 men, mean age 55 ± 14 years) who were first diagnosed with BAV disease by transthoracic echocardiography. We excluded 52 subjects with both significant AS and significant AR. Of the remaining 1,021 subjects, 418 (41%) presented with significant AS, 249 (24%) showed significant AR, and the rest of the subjects were grouped into a normal functioning BAV (n = 354, 35%). BAV morphology was classified into the following 4 types according to position and pattern of raphe and cusps: (1) fusion of the right and left coronary cusps (type 1), (2) fusion of the right and noncoronary cusps (type 2), (3) fusion of the left and noncoronary (type 3), and (4) no raphe (type 0). Patients with significant AS were older, more likely to be women than men, and had a higher prevalence of type 0 BAV. Patients with significant AR were younger and were more likely to be men. In multivariate logistic regression analysis, women, older age, and type 0 or type 3 BAV were associated with significant AS. In contrast, men, hypertension, and chronic kidney disease were correlated with significant AR. Significant valve dysfunction in adults with first diagnosed BAV was closely associated with age, gender, and BAV morphology.

Bicuspid aortic valve outcomes

BACKGROUND

Bicuspid aortic valve is the most common CHD. Its association with early valvular dysfunction, endocarditis, thoracic aorta dilatation, and aortic dissection is well established.

OBJECTIVE

The aim of this study was to assess the incidence and predictors of cardiac events in adults with bicuspid aortic valve.

METHODS

We carried out a retrospective analysis of cardiac outcomes in ambulatory adults with bicuspid aortic valve followed-up in a tertiary hospital centre. Outcomes were defined as follows: interventional - intervention on the aortic valve or thoracic aorta; medical - death, aortic dissection, aortic valve endocarditis, congestive heart failure, arrhythmias, or ischaemic heart disease requiring hospital admission; and a composite end point of both. Kaplan-Meier curves were generated to determine event rates, and predictors of cardiac events were determined by multivariate analysis.

RESULTS

A total of 227 patients were followed-up over 13±9 years; 29% of patients developed severe aortic valve dysfunction and 12.3% reached ascending thoracic aorta dimensions above 45 mm. At least one cardiac outcome occurred in 38.8% of patients, with an incidence rate at 20 years of follow-up of 47±4%; 33% of patients were submitted to an aortic valve or thoracic aorta intervention. Survival 20 years after diagnosis was 94±2%. Independent predictors of the composite end point were baseline moderate-severe aortic valve dysfunction (hazard ratio, 3.19; 95% confidence interval, 1.35-7.54; p<0.01) and aortic valve leaflets calcification (hazard ratio, 4.72; 95% confidence interval, 1.91-11.64; p<0.005).

CONCLUSIONS

In this study of bicuspid aortic valve, the long-term survival was excellent but with occurrence of frequent cardiovascular events. Baseline aortic valve calcification and dysfunction were the only independent predictors of events.

The extent of the raphe in bicuspid aortic valves is associated with aortic regurgitation and aortic root dilatation

Background

The clinical course of bicuspid aortic valves (BAVs) is variable. Data on predictors of aortopathy and valvular dysfunction mainly focus on valve morphology.

Aim

To determine whether the presence and extent of the raphe (fusion site of valve leaflets) is associated with the degree of aortopathy and valvular dysfunction in patients with isolated BAV and associated aortic coarctation (CoA).

Methods

Valve morphology and aortic dimensions of 255 BAV patients were evaluated retrospectively by echocardiography.

Results

BAVs with a complete raphe had a significantly higher prevalence of valve dysfunction (especially aortic regurgitation) than BAVs with incomplete raphes (82.9 vs. 66.7 %, p = 0.01). Type 1A BAVs (fusion of right and left coronary leaflets) and complete raphe had larger aortic sinus diameters compared with the rest of the population (37.74 vs. 36.01, p = 0.031). Patients with CoA and type 1A BAV had significantly less valve regurgitation (13.6 vs. 55.8 %, p < 0.001) and smaller diameters of the ascending aorta (33.7 vs. 37.8 mm, p < 0.001) and aortic arch (25.8 vs. 30.2 mm, p < 0.001) than patients with isolated BAV.

Conclusions

Type 1A BAV with complete raphe is associated with more aortic regurgitation and root dilatation. The majority of CoA patients have incomplete raphes, associated with smaller aortic root diameters and less valve regurgitation.