What is the recommended screening approach for a patient suspected of having a bicuspid aortic valve (BAV), particularly those with a family history of BAV or symptoms such as chest pain, shortness of breath, or palpitations?

Screening for Bicuspid Aortic Valve

Transthoracic echocardiography (TTE) is the primary screening modality for bicuspid aortic valve, and should be performed in all patients with suspected BAV to evaluate valve morphology, assess severity of stenosis or regurgitation, measure aortic dimensions at multiple levels (annulus, sinuses of Valsalva, sinotubular junction, mid-ascending aorta), and screen for associated abnormalities including aortic coarctation. 1

Initial Diagnostic Approach

Primary Screening Tool

• TTE is indicated as the first-line imaging modality for patients with known or suspected BAV, providing comprehensive assessment of valve anatomy, hemodynamics, and aortic dimensions 1
• The echocardiogram must include Doppler interrogation of the proximal descending and abdominal aorta to evaluate for coarctation, which can also be detected by comparing arm and leg blood pressures 1
• Aortic measurements should be systematically obtained at the aortic annulus, sinuses of Valsalva, sinotubular junction, and mid-ascending aorta 1

Advanced Imaging When TTE is Inadequate

• Cardiac MRI or CT angiography is indicated when TTE cannot accurately visualize the aortic sinuses, sinotubular junction, or the proximal 5-6 cm of the ascending aorta 1
• MRI is preferred over CT when feasible due to absence of radiation exposure, particularly important given these patients require lifelong serial imaging 2
• The choice between CMR and CT depends on patient characteristics, institutional expertise, renal function, insurance coverage, and radiation concerns 1

Family Screening Protocol

Who Should Be Screened

• Screening TTE might be considered in first-degree relatives (parents, siblings, children) of patients with known BAV to detect asymptomatic BAV or aortic dilation 1
• This recommendation is particularly important for first-degree relatives of BAV patients with root phenotype aortopathy and/or isolated aortic regurgitation 1, 2
• The prevalence of BAV in first-degree relatives ranges from 9-20%, and family members may also have isolated aortic dilation without BAV 1

Rationale for Family Screening

• BAV demonstrates familial clustering in 20-30% of cases with autosomal dominant inheritance patterns and incomplete penetrance 1
• Obligate carriers in families may have BAV, aortic dilation, both, or neither 1
• If TTE inadequately visualizes the ascending aorta in family members, CT or MRI should be performed since aortic dilation can occur without BAV 1

Clinical Context and Associated Findings

Symptoms Prompting Evaluation

When patients present with chest pain, shortness of breath, or palpitations, TTE screening should specifically assess for:

• Severity of aortic stenosis (12-37% of BAV patients develop moderate or greater AS during follow-up) 1
• Severity of aortic regurgitation (13-30% develop moderate or greater AR) 1
• Aortic dimensions, as 20-40% of BAV patients have aortic enlargement at the sinuses or ascending aorta 1

Associated Abnormalities to Screen For

• Aortic coarctation must be evaluated as it is associated with BAV in a subset of patients 1
• Screen for other congenital defects including ventricular septal defect and patent ductus arteriosus 3
• Consider genetic syndromes such as Turner syndrome, Marfan syndrome, or Loeys-Dietz syndrome, which have increased BAV prevalence 1

Important Caveats

Limitations of Screening Evidence

• While imaging can identify BAV and aortic dilation in family members, there is limited data on cost-effectiveness of family screening and whether earlier diagnosis improves long-term clinical outcomes 1
• Despite this uncertainty, the ACC/AHA guidelines provide a Class 2b recommendation (may be considered) for family screening, reflecting the balance between potential benefit and lack of definitive outcome data 1

Genetic Testing Considerations

• Most patients with BAV and thoracic aortic aneurysms will not have an identifiable pathogenic genetic variant even when familial 1
• When BAV is familial, evaluation by a medical geneticist or specialist in genetic aortopathy should be considered for counseling and genetic testing 1
• Specific genes implicated include NOTCH1, ACTA2, MAT2A, SMAD6, and LOX, though genetic causes remain poorly understood in most cases 1, 4

Risk Stratification

• BAV affects 0.5-2% of adults with 3:1 male predominance 1
• The morphologic phenotype of BAV is important to identify, as fusion involving the noncoronary cusp is associated with higher risk of ascending aorta dilation 2
• Patients require lifelong surveillance even if initially asymptomatic, as valve dysfunction and aortic growth can occur without symptoms 1