What is the management and treatment for a dilated aortic root?

Management of Dilated Aortic Root

Immediate Risk Stratification and Surveillance

For most patients with dilated aortic root, surgical intervention is indicated at ≥5.5 cm diameter, but this threshold drops significantly to ≥5.0 cm for the aortic root specifically and even lower (≥4.5-5.0 cm) in patients with genetic aortopathies like Marfan syndrome. 1, 2

Initial Assessment

• Obtain transthoracic echocardiography (TTE) to measure aortic root dimensions at the sinuses of Valsalva, with CT or MRI when TTE visualization is inadequate 2
• Index measurements to body surface area (BSA) using appropriate nomograms, as normal dimensions vary with age, gender, and body size 1, 2
• Measure both the aortic root and mid-ascending aorta separately, as they have distinct natural histories—root dilatation carries significantly higher risk than ascending aortic dilatation alone 3
• Calculate aortic root area/height ratio (cm²/m), with ≥10 cm²/m considered abnormal and associated with 4-fold increased mortality risk 4

Surveillance Intervals Based on Diameter

• <4.0 cm: Imaging every 2 years 2
• 4.0-4.4 cm: Annual imaging 2
• ≥4.5 cm: Every 6 months or more frequently 2
• Growth rate >0.5 cm/year: Warrants immediate surgical referral regardless of absolute diameter 1, 2

Medical Management

First-Line Pharmacotherapy

• Beta-blockers are first-line therapy for Marfan syndrome patients to reduce aortic root growth rate by decreasing heart rate and myocardial contractility 1, 2
• Angiotensin receptor blockers (ARBs) effectively slow aortic root growth in Marfan syndrome, with combination beta-blocker plus ARB therapy being reasonable 2
• For non-Marfan patients with aortic regurgitation and hypertension, use ACE inhibitors or dihydropyridine calcium channel blockers 2

Critical Caveat

• Avoid beta-blockers in patients with severe aortic regurgitation as they prolong diastole and may increase regurgitant volume 2

Surgical Indications

Size-Based Thresholds (External Diameter)

The 2022 ACC/AHA guidelines establish clear diameter thresholds that vary by underlying pathology:

• ≥5.0 cm for isolated aortic root dilatation (lower than the 5.5 cm threshold for mid-ascending aorta, reflecting the higher malignancy of root dilatation) 1, 3
• ≥5.0 cm for bicuspid aortic valve patients 2
• ≥4.5-5.0 cm for Marfan syndrome 1, 2
• **<5.0 cm in Marfan syndrome if:** rapid growth (>0.5 cm/year), family history of dissection at smaller diameter, or significant aortic regurgitation 1

Non-Size Indications

• Rapid growth rate >0.5 cm/year at any diameter 1, 2
• Symptoms attributable to aortic dilatation 2
• Significant aortic regurgitation requiring valve intervention 1

Surgical Approach Selection

Valve-Sparing vs. Valve Replacement

If the aortic valve is suitable for sparing or repair (no large fenestrations, minimal calcification), valve-sparing aortic root replacement is reasonable when performed by experienced surgeons in a Multidisciplinary Aortic Team. 1

• Valve-sparing procedures (David or Yacoub operations) are preferred in suitable candidates at high-volume centers 1
• If the aortic valve is unsuitable for sparing, mechanical or biological valved conduit aortic root replacement is indicated 1
• Long-term outcomes are similar between mechanical and biological valved conduits, even in patients <70 years old 1

Operative Mortality

• Elective aortic root replacement carries 2.2% operative mortality at experienced centers 1
• Emergency surgery has 17.2% mortality—emphasizing the critical importance of prophylactic intervention at appropriate thresholds 1

Special Population Considerations

Marfan Syndrome

• Pregnant women with Marfan syndrome require surgical intervention if aortic diameter exceeds 4.0 cm before conception 1, 2
• All women with Marfan syndrome warrant frequent cardiovascular monitoring throughout pregnancy and puerperium 1
• Cesarean section with concomitant aortic repair is recommended for dissections during pregnancy 1
• Lifelong surveillance of the entire aorta is mandatory post-repair, as dissection can occur in distal segments 1, 2

Bicuspid Aortic Valve

• First-degree relatives should undergo echocardiographic screening 2
• Lower surgical threshold (≥5.0 cm) applies 2

Loeys-Dietz Syndrome

• Even more aggressive surgical approach than Marfan syndrome may be warranted given higher dissection risk 1

Post-Surgical Management

• Continue beta-blockers and/or ARBs indefinitely, particularly in Marfan syndrome patients 2
• Continued surveillance of remaining aorta is essential—patients remain at risk for aneurysm formation and dissection in other segments 2
• Monitor arch and descending aorta routinely, as these become sites for later-onset aneurysms after ascending repair 1

Critical Pitfalls to Avoid

• Do not use the 5.5 cm threshold uniformly—the aortic root requires intervention at 5.0 cm, and genetic aortopathies require even earlier intervention 1, 3
• Do not measure only internal diameter on echocardiography and compare to CT/MRI external diameter thresholds—external diameter is 0.2-0.4 cm larger than internal diameter 1
• Do not delay referral to a Multidisciplinary Aortic Team at high-volume centers—outcomes are significantly better at experienced centers 1
• Do not assume stability without serial imaging—growth rate is as important as absolute diameter 1, 2