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Untreated Thoracic Aortic Aneurysms: Clinical Outcomes
Quick Takes
- In this cohort of patients with aortic arch and descending thoracic aortic aneurysms, predictors of all-cause and aneurysm-related death included aneurysm size (higher risk with diameter ≥6.0 cm), rapid aneurysm growth, age, and female sex.
- Aortic arch aneurysms tended to be slower growing than descending thoracic aortic aneurysms.
Study Questions:
What is the natural history of untreated thoracic aortic aneurysms involving the arch and/or descending aorta?
Methods:
ETTAA (Effective Treatments for Thoracic Aortic Aneurysms) was a prospective observational study enrolling United Kingdom National Health Service (NHS) patients aged ≥18 years with new or existing arch or descending thoracic aortic aneurysms ≥4 cm in diameter, as seen on computed tomography (CT) or magnetic resonance imaging (MRI). Patients with isolated ascending aortic aneurysms and acute aortic dissections were excluded. At consent, patients were grouped by intended management: watchful waiting (for patients with small aneurysms at low risk of rupture), endovascular stent grafting, open surgical replacement, or conservative management (CM; for patients with aneurysms at risk of rupture but who also had multiple comorbidities or high operative risk, or who declined intervention). Outcomes assessed included aneurysm growth, survival, quality of life, and hospital admissions.
Results:
From 2014–2018, 886 patients (36.2% women, mean age 70.9 years) were recruited, of whom 82 (9.3%) were assigned to CM, and of whom 19 were excluded because they underwent surgery on the day of enrollment. Median follow-up period was 2.06 years for CM patients and 1.35 years for others. Maximum aneurysm diameter was in the descending thoracic aorta in 82% of patients. Mean annual aneurysm growth was 0.2 cm in the descending aorta and 0.07 cm for arch aneurysms ≥4 cm.
A total of 46 CM patients died during follow-up (20.0% per patient-year), and 83 patients from the other groups died (6.6% per patient-year). Of 307 patients with aneurysms ≥6.0 cm, 76 died (23.1% per patient-year), and 42 of these were aneurysm-related deaths (12.7% per patient-year). Three-year probability of death in patients with 5-cm aneurysms was approximately 12%. In multivariable analysis, significant predictors of all-cause and aneurysm-related deaths were female sex (hazard ratios [HRs] 1.78 and 2.60, respectively), age (HRs 1.80 and 1.50 per decade, respectively), and baseline maximum aneurysm diameter (HRs 1.88 and 2.16 per cm, respectively). Increase in aneurysm diameter was associated with increases in overall and aneurysm-related death (for 1 cm growth, HR 2.02 and 2.35, respectively). Hospital admission rates were significantly related to maximum aneurysm diameter (relative rate 1.21 per cm, p = 0.008). Aneurysm size was not associated with quality of life.
Conclusions:
Predictors of all-cause and aneurysm-related death in this population included aneurysm size (higher risk with diameter ≥6.0 cm), rapid aneurysm growth, age, and female sex. Aortic arch aneurysms tended to be slower-growing than descending thoracic aortic aneurysms.
Perspective:
The authors suggest that their findings provide support for upwardly adjusting the current European and American guideline thresholds for intervention on thoracic aortic aneurysms (≥5.5 cm in the arch and ≥6.0 cm in the descending aorta), given that patients with 5-cm aneurysms had relatively low adverse event rates in this study. However, it is likely that the data were affected by selection bias, as patients deemed to be at higher risk of adverse events would have undergone early surgery and been excluded from analysis. As aortic arch aneurysms tended to be slower-growing than descending thoracic aneurysms, longer reimaging intervals (>1 year) may be appropriate for patients with arch aneurysms, provided that early follow-up data are reassuring. The findings of this study should not be extrapolated to management of patients with ascending aortic aneurysms, as such patients were excluded from the cohort.
Clinical Topics: Cardiac Surgery, Cardiovascular Care Team, Geriatric Cardiology, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Vascular Medicine, Aortic Surgery, Interventions and Imaging, Interventions and Vascular Medicine, Computed Tomography, Magnetic Resonance Imaging, Nuclear Imaging
Keywords: Aneurysm, Dissecting, Aortic Aneurysm, Aortic Aneurysm, Thoracic, Cardiac Surgical Procedures, Conservative Treatment, Diagnostic Imaging, Endovascular Procedures, Geriatrics, Magnetic Resonance Imaging, Quality of Life, Stents, Tomography, X-Ray Computed, Vascular Diseases
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