Bicuspid Aortic Valve

Monogenic (Mendelian): a minority, familial/syndromic forms (e.g. NOTCH1, aortopathy genes)^[1]

Acquired: not a cause (congenital malformation)

Complex (likely polygenic): the majority, multifactorial/polygenic; ~9–10% of first-degree relatives affected^[1]

Inheritance: Complex oligogenic/polygenic, familial clustering is well-established but inheritance pattern is not simple Mendelian in most families.^[2]

Familial proportion: Approximately 10% of first-degree relatives of BAV probands are also affected; heritability estimated at ~75%. Some families with NOTCH1 pathogenic variants show autosomal dominant transmission with reduced penetrance (~20–25%).^[1]

Associated genes: NOTCH1 (familial BAV, strongest evidence), GATA5 (rare familial cases)

Screen first-degree relatives: echocardiography recommended given 10% prevalence in relatives^[1]

1-2% of general population

Male:female ratio 2-3:1

Familial clustering suggests genetic component

Confirming the diagnosis: transthoracic echocardiography is first-line and usually diagnostic, it identifies two cusps (often with a fusion raphe) and the Sievers pattern (most commonly right–left coronary cusp fusion). When the ascending aorta is dilated or not well seen on echo, CT or CMR angiography is mandatory to measure the whole ascending aorta and arch.^[1][2]

Valve complications:

• Aortic stenosis (accelerated calcification, typically 5th–6th decade)
• Aortic regurgitation
• Infective endocarditis (increased risk)

Aortopathy:

• Ascending aortic dilatation (~50% of BAV patients)
• Aortic dissection risk (~8–9× higher than general population)
• Can occur even with a normally functioning valve

Family screening: echocardiographic screening of the valve and aorta is recommended for first-degree relatives.^[1]

Echocardiography: Identify BAV morphology and leaflet fusion pattern, assess valve function (AS/AR severity), measure aortic root and ascending aorta, annually^[1]

CT/MR angiography: Full aortic imaging if ascending aorta ≥40mm on echo; required for surgical planning^[2]

Family screening: Echocardiography for all first-degree relatives (10% prevalence)^[1]

Surveillance:

• TTE at diagnosis to define valve function and aortic dimensions.^[1]
• Aorta <40 mm and stable with normal valve: re-image every 1–2 years; sooner if dilated, growing, or valve dysfunction.^[3]
• Use CT/CMR when the ascending aorta is ≥45 mm or not adequately seen on echo.^[2]

Surgery, ascending aorta (thresholds):

1. ≥55 mm regardless of other factors.^[1]
2. ≥50 mm with a risk factor, rapid growth (>3–5 mm/yr), family history of dissection, aortic coarctation, or refractory hypertension.^[1][3]
3. ≥45 mm if already undergoing aortic valve surgery, or at an experienced centre with risk factors.^[1]

Surgery, valve: standard AS/AR thresholds; repair vs replacement, and the Ross procedure, considered in younger patients.^[1]

Medical: blood-pressure control (target <130/80 mmHg); beta-blocker or ARB if hypertensive or aorta dilated. Endocarditis-prevention advice and good dental hygiene.

• Aortic stenosis: often earlier than in tricuspid valves, and/or aortic regurgitation, leading to valve intervention^[1]
• Ascending aortic aneurysm and dissection: the aortopathy progresses independently of valve dysfunction
• Infective endocarditis.
• Association with coarctation of the aorta.

Lifetime risk complications: ~50% require surgery for valve or aorta

Based on ACC/AHA valvular and ESC aortic-disease guidelines^[1][2][3].

Advanced / complicated = aorta ≥45 mm or growth >3 mm/year, severe AS/AR, or symptoms.

	Uncomplicated / Stable	Advanced / Complicated
Frequency	Every 1–2 years	Annual or sooner
Clinical review	Symptoms, BP control	As above
Echocardiography (valve)	Per valve severity (annual if moderate–severe AS/AR)	6–12 monthly
Aortic imaging	Echo of root/ascending aorta: every 3–5 yrs if <40 mm and stable; every 1–2 yrs if 40–45 mm	CT/MRA annually if ≥45 mm, growing, or poorly seen on echo
Family screening	First-degree relative echo (valve + aorta)	–

Disclaimer: This table is general guidance based on published guidelines and does not replace clinical judgement. The responsible clinician is accountable for determining the appropriate, individualised follow-up plan for each patient.

• Lifelong surveillance required even if valve functioning normally^[1]
• Screen first-degree relatives (echo)
• Endocarditis prophylaxis NO longer recommended (except post-repair/prosthetic valve)^[1]
• Aortopathy can progress independently of valve disease^[1]