What is the surgical approach for an ascending aorta with an increased diameter (Ascending Aortic Aneurysm)?

From the Guidelines

Surgery for an ascending aorta aneurysm is generally recommended when the diameter reaches 5.5 cm or greater in most patients, as indicated by the most recent guidelines 1. However, for patients with genetic conditions like Marfan syndrome, bicuspid aortic valve, or family history of aortic dissection, surgery is often recommended at smaller diameters of 4.5-5.0 cm. The threshold may also be lower (around 5.0 cm) for patients who need heart surgery for other reasons, such as valve replacement. Some key points to consider include:

• Surgery becomes urgent regardless of size if the aneurysm is rapidly growing (more than 0.5 cm per year), causing symptoms, or if there's evidence of dissection, as stated in the 2022 ACC/AHA guideline 1.
• The most common procedure is an open surgical repair where the damaged section of the aorta is replaced with a synthetic graft.
• Regular imaging follow-up is essential for patients with smaller aneurysms to monitor for growth that would indicate the need for surgical intervention, as emphasized in the European Heart Journal 1.
• The risk calculation that when the aorta reaches these diameters, the risk of life-threatening complications like rupture or dissection begins to outweigh the risks associated with surgery, is a crucial factor in determining the need for surgical intervention, as discussed in the Circulation journal 1.

Some important considerations for surgical intervention include:

• The presence of symptoms attributable to the aneurysm, which is an indication for surgery, as stated in the 2022 ACC/AHA guideline 1.
• The growth rate of the aneurysm, with a growth rate of ≥0.3 cm/y in 2 consecutive years, or ≥0.5 cm in 1 year, being an indication for surgery, as recommended in the Circulation journal 1.
• The maximum diameter of the aneurysm, with a diameter of ≥5.5 cm being the primary criterion for elective surgical repair, as indicated in the Circulation journal 1.

Overall, the decision to perform surgery for an ascending aorta aneurysm should be based on a careful evaluation of the individual patient's risk factors and the potential benefits and risks of surgical intervention, as emphasized in the European Heart Journal 1 and the Circulation journal 1.

From the Research

Diameter Ascending Aorta Surgery

• The current American and European guidelines agree that the threshold for the diameter for elective replacement of the ascending aorta in non-syndromic, asymptomatic aneurysmal disease is 5.5 cm 2.
• However, several studies have shown that nearly 50% of patients with an acute type A aortic dissection present with an aortic diameter <5.5 cm 3, 4.
• A study found that the maximum ascending aortic diameter at the time of dissection was 5.13±0.66 cm, significantly lower than the guidelines-derived surgical threshold of 5.5 cm 4.
• Another study suggested that aortic diameter was placed in context vis-a-vis the normal distribution in the general population with similar sex, age and body surface area, by conversion to z scores, and found that the risk curves unveiled generalized thresholds of z = 4 for the aortic root and z = 5 for the mid-ascending aorta 5.
• The study also found that these correspond to individualized thresholds of less than the standard criterion of 5.5 cm in the vast majority of patients, for example, a 75-year-old typical male with 2.1 m2 body surface area, who was found to be at increased risk of adverse events if root diameter exceeds 5.15 cm, or mid ascending exceeds 5.27 cm 5.
• A study on uncomplicated acute type B aortic dissection found that ascending aortic diameter >40.8 mm and ascending aortic area >12.1 cm2 were associated with subsequent arch and proximal progression necessitating open ascending aortic repair 6.

Individualized Thresholds

• The use of individualized thresholds based on patient-specific characteristics such as sex, age, body surface area, and aneurysm location may be more effective in preventing aortic dissections 5.
• An automated calculator can be used to identify patients at high risk of adverse events based on these characteristics 5.
• The calculator can help determine the optimal diameter threshold for each patient, which may be lower than the standard 5.5 cm threshold 5.

Risk Factors

• Several factors can increase the risk of aortic dissection, including aortic diameter, age, sex, body surface area, and aneurysm location 2, 3, 5, 6, 4.
• A study found that ascending aortic diameter >40.8 mm and ascending aortic area >12.1 cm2 were predictive of decreased intervention-free survival in patients with uncomplicated acute type B aortic dissection 6.
• Another study found that mean "actual" preoperative Euroscore II was 10.43±4.07 which was significantly higher than the 1.47±0.57 "predicted" Euroscore II, indicating a higher risk of mortality in patients with acute type A aortic dissection 4.