What is the recommended management for a patient with a Sievers type 1 bicuspid aortic valve and mild aortic regurgitation?

Management of Sievers Type 1 Bicuspid Aortic Valve with Mild Aortic Regurgitation

For a patient with Sievers type 1 bicuspid aortic valve (pseudoraphe between right-left cusps) and mild aortic regurgitation, serial echocardiographic surveillance every 3-5 years is recommended, with mandatory assessment of the ascending aorta by CT or MRI at initial diagnosis to evaluate for associated aortopathy. 1

Initial Diagnostic Evaluation

• Perform comprehensive transthoracic echocardiography (TTE) to assess valve morphology, quantify aortic regurgitation severity, measure left ventricular dimensions and function, and evaluate aortic root and ascending aorta diameters at multiple levels (annulus, sinuses of Valsalva, sinotubular junction, mid-ascending aorta). 1

• Obtain CT angiography or cardiac MRI of the entire thoracic aorta at initial diagnosis, as approximately 50% of bicuspid aortic valve patients have associated aortopathy. 1, 2 Cardiac MRI is preferred in younger patients to avoid cumulative radiation exposure. 2

• Screen first-degree relatives with TTE for bicuspid aortic valve and aortopathy, particularly when the patient has root phenotype aortopathy or isolated aortic regurgitation. 1

Surveillance Strategy

For Mild Aortic Regurgitation with Normal Aortic Dimensions (<40 mm):

• Perform TTE every 3-5 years to monitor progression of aortic regurgitation, left ventricular size and function, and aortic dimensions. 1, 3

• Repeat aortic imaging (CT/MRI) every 3-5 years if no aortic dilation is present. 2

For Mild Aortic Regurgitation with Aortic Dilation (≥40 mm):

• Perform TTE annually to assess for progression. 1, 3

• Repeat aortic imaging (CT/MRI) annually when aortic diameter exceeds 40 mm or if notable interval change in dimensions occurs. 2

• Increase surveillance frequency to every 6 months if rapid aortic growth (>0.5 cm/year) is documented. 3

Medical Management

• Control blood pressure aggressively if hypertension is present, using any effective antihypertensive agent. 1

• Beta-blockers or angiotensin receptor blockers (ARBs) may be considered for patients with aortic dilation, though evidence for slowing progression in bicuspid aortic valve-associated aortopathy is limited. 1, 3

• Avoid beta-blockers if aortic regurgitation becomes moderate or severe, as they may increase regurgitant volume by prolonging diastole. 3

Surgical Indications

For the Aortic Valve:

• Surgery is NOT indicated for mild aortic regurgitation with normal left ventricular size (end-diastolic dimension <65 mm, end-systolic dimension <55 mm) and preserved ejection fraction (≥50%). 1

• Surgery becomes indicated when aortic regurgitation progresses to severe AND any of the following develop: symptoms, left ventricular ejection fraction <50%, left ventricular end-systolic dimension ≥50 mm, or left ventricular end-diastolic dimension ≥65 mm. 1

For the Ascending Aorta:

• Surgery is recommended when ascending aorta diameter reaches ≥55 mm in most patients with bicuspid aortic valve. 1

• Surgery is recommended at ≥50 mm specifically for bicuspid aortic valve patients with root phenotype aortopathy (dilation primarily at sinuses of Valsalva). 1

• Consider surgery at lower thresholds (45-50 mm) if there is a family history of aortic dissection or rapid progression (>0.5 cm/year). 1, 3

Special Considerations for Sievers Type 1 Morphology

Sievers type 1 bicuspid aortic valves (with raphe) carry specific risks that warrant attention:

• Higher rates of paravalvular regurgitation occur with transcatheter aortic valve replacement in type 1 morphology due to the calcified raphe preventing adequate stent apposition. 1

• Post-implantation aortic regurgitation is more common in type 1 bicuspid valves (34.2%) compared to type 0 (13.3%) when transcatheter procedures are performed. 1

• Ascending aortic dilation patterns may differ based on which cusps are fused, though right-left cusp fusion (the most common pattern) shows slower aortic progression (0.36 mm/year) compared to right-noncoronary fusion (0.65 mm/year). 4

Clinical Follow-Up

• Assess for new symptoms annually, including dyspnea, chest pain, syncope, or reduced exercise tolerance. 5

• Recognize that 42% of patients develop cardiovascular events within 20 years of diagnosis, even with initially mild dysfunction. 5

• Age >50 years and echocardiographic valve degeneration (calcification, thickening, reduced mobility) at diagnosis independently predict higher event rates requiring more intensive surveillance. 5

Common Pitfalls to Avoid

• Do not rely solely on color Doppler jet assessment for aortic regurgitation severity in bicuspid valves, as eccentric jets may underestimate severity; use vena contracta width (≥0.6 cm indicates severe AR), holodiastolic flow reversal in descending aorta, and left ventricular dimensions. 1

• Do not assume adequate aortic imaging from TTE alone; the ascending aorta beyond the proximal 2-3 cm is often inadequately visualized and requires CT or MRI. 1

• Do not delay aortic imaging until symptoms develop; aortic complications can occur independently of valve dysfunction severity. 1