B.1. What are the indications and timing of surgical intervention for TAAs?
Answer:
Patients diagnosed with aneurysms of the thoracic aorta require frequent surveillance to assess for aneurysmal expansion. The goal is to facilitate surgical intervention prior to the onset of aortic dissection or aneurysm rupture. Important considerations include the appropriate interval for surveillance imaging and the diameter at which surgical intervention should be recommended.
Patients diagnosed with TAAs and TAAAs should undergo initial CT or MRI to define the size and extent of the aneurysm. Follow-up surveillance imaging is typically performed 6 months after diagnosis, with continued follow-up imaging at an interval determined by the rate of growth. These aneurysms tend to grow slowly, with arch and ascending aneurysms growing 0.1 cm/y and descending aneurysms growing 0.3 cm/y.
Determining when to intervene depends on the underlying pathology, size, rate of expansion, and presence or absence of symptoms (Table 9.2). In patients without known connective tissue disease, surgical repair is recommended at 5.5 cm. In patients with concomitant aortic valve (AV) disease who are scheduled to undergo AV replacement, an aneurysm should be repaired if it is greater than or equal to 4.5 cm in diameter. Patients with symptomatic aneurysms of any size should be considered for surgical intervention. Very large and very small patients may be better managed by indexing aortic diameter to body size to determine the appropriate timing of repair.
Table 9.2: Guidelines for Elective Intervention in Selected Categories of Asymptomatic Patients With Ascending or Descending Thoracic Aneurysms
| Associated Condition with Aneurysm | Diameter Size for Surgical Intervention |
|---|---|
| Sporadic | ≥5.5 cm |
| Heritable without Genetic Identification | ≥5.0 cm |
| Marfan Syndrome | ≥5.0 cm ≥4.5 cm with features associated with increased risk of dissection present |
| Loeys-Dietz Syndrome | ≥4.5 cm - 5.0 cm, dependent on specific pathogenic variant, phenotypic features, patient age, aortic growth rates, and family history |
| BAV Aortopathy | ≥5.5 cm 5.0 - 5.4 cm with additional risk factors for aortic dissection ≥4.5 cm with concomitant surgical aortic valve repair or replacement |
BAV, bicuspid aortic valve; TAA, thoracic aortic aneurysm.
Special recommendations exist for patients with underlying connective tissue disorders because these patients tend to suffer significant aortic events at smaller aortic diameters. Patients with MFS and LDS require frequent surveillance, with CT imaging 6 months after initial diagnosis followed by surveillance frequency depending on size and rate of growth. Earlier repair is acceptable and recommended in MFS and LDS, and the timing of a surgical intervention can be based on the presence of associated risk factors for aortic dissection, such as a family history of aortic dissection, accelerated growth rate, and aortic coarctation. Aneurysm repair for patients with BAV presenting for AV repair or replacement should be performed at a diameter of greater than or equal to 4.5 cm. Females with aortic aneurysms contemplating pregnancy might be candidates for prophylactic intervention at smaller aneurysm diameters in the context of connective tissue disorders and other risk factors for aortic dissection.
Overall, surgical decision-making in patients with TAAs, thoracoabdominal aneurysms, and combined aneurysmal and AV disease requires a careful comparison of operative risk with the risk of a significant aortic event. Consideration of medical comorbidities and the underlying pathology adds additional nuance to the decision of whether to undertake a surgical repair, and when that repair is recommended, what surgical technique should be utilized.
References
- Harik L, Lau C. Open and endovascular repair of thoracoabdominal aortic aneurysm-a narrative review. J Thorac Dis. 2023;15:3984-3997.
- Isselbacher EM, Preventza O, Hamilton Black J 3rd, et al; Peer Review Committee Members. 2022 ACC/AHA guideline for the diagnosis and management of aortic disease: a report of the American Heart Association/American College of Cardiology Joint Committee on clinical practice guidelines. Circulation. 2022;146:e334-e482.