What is the recommended screening and treatment for a dilated aortic root?

Screening and Management of Dilated Aortic Root

For patients with a dilated aortic root ≥4.0 cm, lifelong surveillance imaging with transthoracic echocardiography (TTE), CT, or MRI is required at intervals determined by aortic diameter and growth rate, with surgical intervention typically considered at ≥5.0-5.5 cm depending on underlying etiology. 1

Initial Screening and Diagnosis

Who Should Be Screened

• First-degree relatives of patients with bicuspid aortic valve (BAV) and aortopathy should undergo TTE screening, as the prevalence of BAV in relatives ranges from 9-20% 1
• If TTE inadequately visualizes the ascending aorta, CT or MRI must be performed to fully evaluate aortic size, as family members may have aortic dilation without BAV 1
• Patients with Marfan syndrome, Loeys-Dietz syndrome, or other heritable thoracic aortic diseases require baseline imaging from head to pelvis with CT or MRI to evaluate the entire aorta and branch vessels 1

Initial Imaging Protocol

• TTE is the primary screening modality for assessing aortic root and proximal ascending aorta 2
• CT or MRI should confirm TTE measurements, rule out aortic asymmetry, and establish baseline diameters for follow-up 2
• Complete assessment of the entire aorta is required at baseline to identify additional aneurysms 2

Critical pitfall: Echocardiography can underestimate aortic root size by an average of 2.5 mm compared to CT, with greater underestimation as the aortic root enlarges 3. This is particularly important when measurements approach surgical thresholds.

Surveillance Intervals Based on Aortic Diameter

For Non-Heritable Aortopathy (Including BAV)

40-44 mm diameter:

• Baseline CT or MRI confirmation, then TTE reimaging in one year 2
• For BAV patients with diameter ≥4.0 cm, imaging every 2 years if stable and <4.0 cm 1

45-49 mm diameter:

• Annual imaging with TTE after CT/MRI confirmation 2
• More frequent monitoring (every 6-12 months) for BAV patients depending on growth rate 1

50-54 mm diameter:

• Imaging every 6 months 1, 2
• Surgical evaluation should be initiated 2

≥55 mm diameter:

• Surgical intervention should be considered for tricuspid aortic valve 2
• For BAV, surgery is recommended at ≥5.0 cm 1

For Heritable Thoracic Aortic Disease

Marfan Syndrome:

• TTE at least annually if aortic root <45 mm without risk factors 2
• TTE every 6-12 months if aortic root ≥45 mm 1, 2
• Annual MRI or CT from head to pelvis if dilated or dissected aorta/branches present 1
• Surgical intervention at ≥5.0 cm (lower threshold of 4.5 cm for women desiring pregnancy) 1, 2

Loeys-Dietz Syndrome:

• TTE at baseline and every 6-12 months depending on diameter and growth 1, 2
• Annual MRI or CT from head to pelvis if dilation/dissection present 1
• Surveillance imaging every 2 years if no distal dilation, though may be more frequent based on family history 1
• Lower surgical threshold (≥4.5 cm) due to risk of dissection at smaller diameters 1

ACTA2-Related Disease:

• Annual TTE monitoring of aortic root/ascending aorta 1, 2
• Imaging of entire aorta with MRI/CT every 3-5 years 1
• Surgical consideration at ≥4.5 cm or lower with other risk factors 1

Familial Thoracic Aortic Aneurysm:

• Annual echocardiograms for small dimensions with slow growth 1
• Every 6 months if root exceeds 4.5 cm, growth >0.5 cm/year, or significant aortic regurgitation 1
• Imaging of entire aorta every 2-3 years 1

Indications for More Frequent Monitoring

Increase imaging frequency to every 6 months when: 1

• Diameter >4.5 cm in adults
• Rate of increase >0.5 cm/year
• Significant aortic regurgitation develops
• Aortic root phenotype with predominant regurgitation (higher risk) 1

Critical consideration: Patients with BAV who undergo isolated aortic valve replacement for aortic regurgitation have a 34% rate of adverse aortic events during follow-up if concomitant root dilation (4.0-5.0 cm) is present 1. This underscores the need for continued surveillance post-valve surgery.

Medical Management During Surveillance

Beta-blockers and/or angiotensin receptor blockers (ARBs):

• Recommended in maximally tolerated doses for Marfan syndrome to reduce rate of aortic dilation 2
• Consider combination therapy with both beta-blockers and ARBs in Marfan syndrome 2
• Beta-blockade recommended for Loeys-Dietz syndrome and familial thoracic aortic aneurysm 1

Cardiovascular risk optimization:

• Aggressive blood pressure control is essential, as hypertension is strongly associated with aortic root dilation 4
• Optimize lipid management and other cardiovascular risk factors for all patients with aortic aneurysms 2

Surgical Thresholds

Tricuspid Aortic Valve

• ≥5.5 cm for isolated ascending aortic aneurysm 1, 2

Bicuspid Aortic Valve

• ≥5.0 cm for root phenotype 1
• >5.2 cm for ascending phenotype in low surgical risk patients 1
• ≥4.5 cm if concomitant valve surgery required 1

Marfan Syndrome

• ≥5.0 cm for aortic root 1, 2
• ≥4.5 cm for women desiring pregnancy 1, 2
• ≥5.0 cm for arch, descending, or abdominal aorta 1

Loeys-Dietz Syndrome and High-Risk Genetic Mutations

• ≥4.5 cm due to risk of dissection at smaller diameters 1
• Between 4.5-5.0 cm for MYH11, SMAD3, and ACTA2 mutations 1

Accelerated Growth

• ≥10 mm/year or ≥5 mm/6 months warrants surgical consideration regardless of absolute diameter 2

Post-Operative Surveillance

After aortic valve repair or replacement with residual dilation ≥4.0 cm:

• Lifelong surveillance imaging required at intervals dependent on diameter and growth rate 1
• Higher risk for late aortic events if valve replacement was for aortic regurgitation (34% adverse event rate) versus stenosis 1
• 15-year freedom from aortic events is 85% with baseline dilation versus 93% with normal diameters 1

Special Populations

Athletes with mildly dilated aorta (z-scores 2-2.5 or 40-41 mm in tall men, 36-38 mm in tall women):

• Surveillance every 6-12 months with frequency dependent on size, stability, and sport intensity 1
• Continued enlargement should prompt disqualification from competition as this indicates underlying aortopathy 1
• Long-term surveillance recommended even after retirement from competitive athletics 1

Women with Marfan syndrome considering pregnancy:

• Pre-conception evaluation and imaging of entire aorta required 1, 2
• Prophylactic surgery recommended if diameter >45 mm 1
• May consider surgery at 40-45 mm 1
• Follow-up during pregnancy with frequency determined by diameter and growth 1