From the Guidelines
Thoracic aortic aneurysms should be considered for surgical intervention when they reach a diameter of ≥5.0 cm for patients with a family history of TAAs but with no known pathogenic variant, and at ≥4.5 cm for those with a family history of aortic dissection at a known maximal aortic root or ascending aortic diameter <5.0 cm. The management of thoracic aortic aneurysms is complex and depends on various factors, including family history, genetic conditions, and growth rate 1. For patients with a family history of TAAs, the GenTAC study suggested a higher risk of aortic dissection, with a large proportion of patients not having met the 5.5-cm threshold for elective repair at the time of their aortic dissection 1.
Key Considerations
- Family history of TAAs or aortic dissection
- Presence of genetic conditions
- Growth rate of the aneurysm
- Size of the aneurysm
- Location of the aneurysm (ascending or descending aorta)
Size Thresholds
- ≥5.0 cm for patients with a family history of TAAs but with no known pathogenic variant 1
- ≥4.5 cm for patients with a family history of aortic dissection at a known maximal aortic root or ascending aortic diameter <5.0 cm 1
- ≥5.5 cm for the ascending aorta
- ≥6.0-6.5 cm for the descending thoracic aorta
Monitoring and Surveillance
Regular monitoring is essential, with CT or MRI imaging recommended every 6-12 months for aneurysms approaching surgical thresholds and annually for smaller ones 1. The goal of these recommendations is to balance the risk of aortic complications (dissection or rupture) against surgical risks, as rupture risk increases exponentially with size, while surgical mortality for elective repair at experienced centers is typically low 1.
From the Research
Thoracic Aortic Aneurysm Size
- The size of a thoracic aortic aneurysm is a critical factor in determining the risk of complications and the need for treatment 2, 3, 4.
- Aneurysm diameter is the best predictor of the natural history and risk of complications, with larger aneurysms being at higher risk of rupture 2.
- 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.
- Studies have shown that aneurysm size is an important factor in determining the optimal treatment approach, with endovascular repair being a preferred option for larger aneurysms 4, 5.
- Imaging techniques such as computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are used to assess aneurysm size and monitor growth over time 4, 6.
Factors Influencing Aneurysm Size
- Hypertension and smoking are risk factors for aneurysm growth, and treating these conditions can help slow the growth of the aneurysm 2.
- Connective tissue disorders, bicuspid aortic valves, and familial/genetic predisposition can also influence aneurysm size and risk of complications 2.
- The rate of aneurysm growth is an important factor in determining the need for treatment, with rapidly growing aneurysms being at higher risk of rupture 3.
Treatment Thresholds
- The treatment threshold for thoracic aortic aneurysms is typically based on the aneurysm diameter, with elective treatment recommended for aneurysms > 55 mm in diameter 4.
- However, the optimal treatment approach may vary depending on individual patient factors, such as age, comorbidities, and overall health status 5.