From the Guidelines
Referral for a thoracic aortic aneurysm is generally recommended when the diameter reaches 5.5 cm or greater for most patients. However, this threshold varies based on several factors, as outlined in the 2022 ACC/AHA guideline for the diagnosis and management of aortic disease 1. For patients with high-risk features of rupture, such as rapid aortic growth (≥0.5 cm/y), symptomatic aneurysms, underlying connective tissue disorder or HTAD, saccular aneurysm morphology, female sex, or infected aneurysm, repair at a smaller diameter threshold may be warranted 1.
Key Considerations
- Patients with genetic conditions like Marfan syndrome, Loeys-Dietz syndrome, or familial thoracic aortic aneurysm should be referred at smaller diameters of 4.5-5.0 cm, as suggested by the GenTAC study 1.
- Patients with bicuspid aortic valves should be referred when the aneurysm reaches 5.0 cm, considering their increased risk of aortic dissection or rupture 1.
- The rate of growth is also crucial; aneurysms that expand more than 0.5 cm per year warrant referral regardless of absolute size, due to the increased risk of life-threatening complications like dissection or rupture 1.
- For patients with a family history of aortic dissection or rupture, earlier referral at smaller diameters is prudent, taking into account the size at which the aorta dissected or elective surgery was performed in affected relatives 1.
Management and Surveillance
- Regular imaging surveillance with CT or MRI every 6-12 months is recommended for aneurysms approaching these thresholds.
- Patients should be advised to maintain good blood pressure control (typically below 130/80 mmHg) and avoid heavy lifting or straining activities while awaiting specialist evaluation.
- The decision to refer should be based on the individual patient's risk factors and the potential benefits and risks of intervention, as outlined in the 2022 ACC/AHA guideline 1.
From the Research
Diameter of Thoracic Aortic Aneurysm for Referral
The diameter of a thoracic aortic aneurysm that warrants referral is a critical factor in determining the risk of complications and the need for surgical intervention.
- The study by 2 recommends intervention for the ascending aorta at 5.5 cm and for the descending aorta at 6.5 cm.
- For patients with Marfan's disease or familial thoracic aortic aneurysm, earlier intervention is recommended at 5.0 cm for the ascending and 6.0 cm for the descending aorta 2.
- Another study suggests that surgery at 5.0- to 5.5-cm diameter will prevent most adverse natural events 3.
- The European Society for Vascular Surgery guidelines recommend elective treatment of thoracic aneurysms with a diameter > 55 mm, as diameters of 55 - 60 mm are associated with a rupture risk of 10 %/year 4.
Factors Influencing Referral
Several factors influence the decision to refer a patient with a thoracic aortic aneurysm, including:
- Aortic diameter: the primary predictor of the natural history and risk of complications 5
- Symptoms: symptomatic aneurysms must be resected regardless of size 2, 3
- Genetic syndromes: patients with Marfan's disease or familial thoracic aortic aneurysm require earlier intervention 2
- Family history: first-degree relatives of patients with aortic disease should be evaluated 6