At what aortic root diameter is surgery necessary?

From the Guidelines

Surgery for aortic root dilation is generally recommended when the diameter reaches 5.0 to 5.5 cm for most patients, though this threshold varies based on individual risk factors. The decision for surgery is based on the significantly increased risk of life-threatening complications like aortic dissection or rupture when the aorta reaches these sizes, as the wall tension increases proportionally with the diameter according to Laplace's law 1. For patients with Marfan syndrome or other genetic aortic disorders, surgery is typically recommended at a lower threshold of 4.5 to 5.0 cm due to their higher risk of aortic complications 1. Patients with bicuspid aortic valves may be advised to have surgery at 5.0 to 5.5 cm 1. Key factors influencing the decision for surgery include:

• Growth rate, with rapid expansion of >0.5 cm per year warranting earlier intervention 1
• Family history of aortic dissection
• Presence of aortic valve disease
• Body size, with lower thresholds for smaller patients
• Overall surgical risk Regular imaging follow-up is essential for patients with aortic dilation below surgical thresholds to monitor for progression. The 2022 ACC/AHA guideline for the diagnosis and management of aortic disease provides recommendations for surgical intervention thresholds for aortic aneurysms, including a maximal ascending aortic diameter of 5.5 cm for asymptomatic patients with no elastopathy 1. In patients with a family history of aortic dissection at a known maximal aortic root or ascending aortic diameter <5.0 cm but with no known pathogenic variant, it is reasonable to perform prophylactic aortic repair at a maximal aortic diameter of ≥4.5 cm 1. The guideline also emphasizes the importance of a Multidisciplinary Aortic Team in the management of patients with aortic disease 1.

From the Research

Aortic Root Diameter and Surgery Necessity

• The necessity of surgery for aortic root diameter is a critical consideration in patients with Marfan syndrome or bicuspid aortic valve (BAV) and ascending aortic ectasia.
• According to 2, preventive surgical repair of the moderately dilated ascending aorta/aortic root in patients with BAV is recommended for a maximum ascending aortic/root diameter of 45 mm, as the risk of dissection/rupture raises significantly with an aneurysm diameter >50 mm.
• The European Society of Cardiology (ESC) and the joint guidelines of the American College of Cardiology (ACC)/American Heart Association (AHA) recommend elective repair in symptomatic patients with dysfunctional BAV (aortic diameter ≥45 mm) 2.
• In asymptomatic patients with a well-functioning BAV, elective repair is recommended for diameters ≥50 mm, or if the aneurysm is rapidly progressing (rate of 5 mm/year), or in case of a strong family history of dissection/rupture/sudden death, or with planned pregnancy 2.

Management of Aortic Root Dilation

• Beta-blockers, angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers have been shown to slow the progression of aortic dilation in Marfan syndrome 3, 4, 5.
• Angiotensin receptor blockers (ARBs) have been found to be associated with a slower progression of aortic root dilation when compared with placebo and as an addition to beta-blocker therapy 4.
• However, the evidence for the use of these medications in preventing aortic dissection or reducing mortality is limited, and more methodologically rigorous studies are needed to evaluate their impact on clinical outcomes 3, 5.

Surgical Indications

• The decision to perform surgery on the aortic root should be based on individual patient factors, including the size of the aortic root, the rate of progression, and the presence of symptoms or other risk factors 2.
• Elective aortic root replacement is paramount in preventing aortic dissection and avoiding subsequent problems in the distal aorta 6.