Thoracic aortic aneurysm: Optimal surveillance and treatment

Tom Kai Ming Wang; Milind Y. Desai

doi:10.3949/ccjm.87a.19140-1

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Figure 1
Computed tomography angiography aortic root measurements on (A) axial source image and (B–D) 3-dimensional multiplanar reconstruction (3-D-MPR) double-oblique planes. Note that without 3-D-MPR, the aortic root size is underestimated (A). Also note that sinus-commissure measurements are often slightly less than sinus-sinus measurements in (B).
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Figure 2
Computed tomography of thoracic aortic aneurysm without (A) and with (B) electrocardiographic gating. Note that the motion artifact indicated by the white arrow in (A) is not seen in (B).
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Figure 3
Range of thoracic aortic aneurysm (TAA) pathologies: (A) bicuspid aortic valve aortopathy on computed tomography (CT), (B) Marfan syndrome with pectus excavatum on magnetic resonance imaging, (C) mycotic aortic arch aneurysm on CT, (D) Takayasu arteritis on CT, with thickened, inflamed aortic wall.
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Figure 4
Cross-sectional area-to-height ratio and management-stratification Kaplan-Meier survival curves for (A) aortic root and (B) ascending aorta in 969 consecutive patients with bicuspid aortic valve with proximal aorta diameter ≥ 4 cm, who underwent gated contrast-enhanced thoracic computed tomography or magnetic resonance angiography. Note the worse outcomes for those with aortic root area-to-height ratio > 10 cm²/m, in whom surgery makes a big difference in survival.
Reprinted from Masri A, Kalahasti V, Svensson LG, et al. Aortic cross-sectional area/height ratio and outcomes in patients with bicuspid aortic valve and a dilated ascending aorta. Circ Cardiovasc Imaging 2017; 10(6):e006249. doi:10.1161/CIRCIMAGING.116.00624

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TABLE 1

Thoracic aortic aneurysm: Risk factors, associations, and causes

Risk factors

Older age

Male sex

Hypertension

Smoking

Hypercholesterolemia

Weight-lifting

Cocaine use

Trauma

Cardiovascular associations

Atherosclerosis

Bicuspid aortic valve

Other aneurysm

Prior aortic dissection

Aortic coarctation

Genetic causes

Familial thoracic aortic aneurysm

Marfan syndrome

Loeys-Dietz syndrome

Ehlers-Danlos syndrome

Turner syndrome

Autosomal-dominant polycystic kidney disease

Shprintzen-Goldberg (craniosynostosis) syndrome

Inflammatory causes

Takayasu arteritis

Giant-cell arteritis

Behçet arteritis

Ankylosing spondylitis

Infective causes

Mycotic aortitis

Syphilis

Idiopathic

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TABLE 2

Imaging options for assessing thoracic aortic aneurysm

Considerations	TTE	TEE	CTA	MRA	Aortography
Accuracy of measurement	Medium	Medium	High	High	Low
Extent of aortic assessment	Limited	Medium	Entire	Entire	Limited
Detecting acute aortic syndromes	Poor	Medium	High	High	Poor
Aortic regurgitation and grading	Yes	Yes	No	Yes	Limited
Portable	Yes	Yes	No	No	No
Contrast	No	No	Yes	Yes	Yes
Radiation	No	No	Yes	No	Yes
Cost	Low	Medium	Medium	High	High
Invasive procedure	No	Yes	No	No	Yes
Recommended line of investigation	Second	Third	First	Second	Third

CTA = computed tomography angiography; MRA = magnetic resonance angiography; TEE = transesophageal echocardiography; TTE = transthoracic echocardiography
Based on information in reference 9.

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TABLE 3

Indications for prophylactic intervention for thoracic aortic aneurysm

Aneurysm location and associated conditions	ACC/AHA 2010²	ESC 2014¹	Our recommendation
Ascending aorta No associated conditions	≥ 5.5 cm (I-C)^{^a} ≥ 0.5 cm/year growth (I-C)	≥ 5.5 cm (I-C), lower if small stature, rapid progression, aortic regurgitation (AR), pregnancy, patient preference (IIa-C)	≥ 5.5 cm π r²/H > 10
Aortic valve surgery planned	> 4.5 cm (I-C)	> 4.5 cm	> 4.5 cm
Marfan syndrome	4.0–5.0 cm (I-C) π r²/H > 10 (IIa-C)	≥ 5.0 cm (I-C) > 4.5 cm with risk factors or family history (IIa-C) ≥ 0.3 cm/year growth, severe AR, pregnancy desired (IIa-C)	> 4.5 cm π r²/H > 10
Bicuspid aortic valve	≥ 4.0–5.0 cm (I-C) π r²/H > 10 (IIa-C)	≥ 5.5 cm without risk factors (I-C) ≥ 5.0 cm with risk factors, family history, hypertension, aortic coarctation (I-C) ≥ 4.5 cm if AVR planned (I-C) ≥ 0.3 cm/year growth (IIa-C)	≥ 5.0 cm without risk factors ≥ 4.5 cm with risk factors π r²/H > 10
Turner syndrome	4.0–5.0 cm (I-C) π r²/H > 10 (IIa-C)	Indexed aortic diameter ≥ 27.5 mm/m²	≥ 27.5 mm/m² π r²/H > 10
Loeys-Dietz syndrome (apply to TGFBR1 or TGFBR2 mutation)	≥ 4.2 cm (TEE) (IIa-C) ≥ 4.4–4.6 cm (CTA/MRA) (IIa-C)	≥ 5.0 cm (I-C) ≥ 4.5 cm with risk factors (IIa-C)	≥ 4.5 cm π r²/H > 10
Ehlers-Danlos syndrome	4.0–5.0 cm (I-C) π r²/H > 10 (IIa-C)	No specific threshold recommended	≥ 4.5 cm π r²/H > 10
Familial TAA	4.0–5.0 cm (I-C) π r²/H > 10 (IIa-C)	No specific threshold recommended	≥ 4.5 cm π r²/H > 10
Aortic arch None	≥ 5.5 cm (IIa-B)	≥ 5.5 cm (IIa-C) Consider if having ascending or descending TAA surgery (IIa-C)	≥ 5.5 cm
Descending aorta Stent graft	≥ 5.5 cm (I-B)	≥ 5.5 cm (IIa-C)	≥ 5.5 cm
Surgery	≥ 6.0 cm (I-C) (include high risk, thoracoabdominal)	≥ 6.0 cm (IIa-C)	≥ 6.0 cm
Surgery with degenerative, traumatic or saccular TAA, or postoperative pseudo-aneurysm	≥ 5.5 cm (I-B)	No specific threshold recommended	≥ 5.5 cm
Surgery with connective tissue disorder like Marfan or Loeys-Dietz syndrome	Lower threshold than > 6 cm (I-C)	Lower threshold than > 6 cm	≥ 5.5 cm

↵a Class of recommendation (scale of I to III) and level of evidence (scale of A to C).
ACC = American College of Cardiology; AHA = American Heart Association; AVR = aortic valve surgery; CTA = computed tomographic angiography; ESC = European Society of Cardiology; MRA = magnetic resonance angiography π r²/H = maximal cross-sectional area of TAA divided by height; TAA = thoracic aortic aneurysm

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TABLE 4

Recommendations for measurement and surveillance of thoracic aortic aneurysms

Associated conditions	ACC/AHA 2010²	ESC 2014¹	ASE/EACVI 2015³	Our recommendations
None	No specific recommendations except needing surveillance	No specific recommendations except needing surveillance	Every 1–3 years based on risk after diagnosis	TTE and CTA or MRA at baseline and 6 months; If TAA < 5.0 cm and stable, then yearly If TAA ≥ 5.0 cm or growing > 0.5 cm/year, then every 6 months and refer to surgeon
Marfan syndrome	Measure dimensions and maximum cross-sectional area divided by height TTE at baseline and 6 months, CTA or MRA at baseline to check TTE If stable and < 4.5 cm, then yearly after, if not then more frequently	TTE and MRA or CTA If no TAA at baseline, TTE yearly, MRA or CTA every 5 years If any aneurysm is above root, MRA or CTA yearly Refer to 2010 ESC adult congenital disease guidelines³⁵	Dimensions with normative values based on age, body surface area, and Z scores TTE and CTA or MRA If no TAA at baseline, then every 2–3 years First TAA diagnosis: 6 months then yearly if stable, < 4.5 cm and no dissection history; otherwise every 6 months Postoperatively: 6 months, then yearly if stable CTA or MRA at least every 3 years if using TTE	TTE and CTA or MRA at baseline and 6 months If no TAA, then TTE yearly and CTA or MRA every 2 years First TAA diagnosis: TTE and CTA or MRA yearly if stable (< 0.3 cm/year) and < 4.5 cm, other-wise every 6 months and refer to surgeon
Bicuspid aortic valve	No specific recommendations after initial imaging TTE and CTA or MRA	TTE and CTA or MRA If no TAA at baseline, repeat TTE yearly If TAA > 4.5 cm or growing at > 3 mm/year, then do CTA or MRA to confirm at same time, then yearly	TTE and CTA or MRA If no at baseline, repeat every 3–5 years First TAA diagnosis: 6 months then yearly if stable, < 4.5 cm and no dissection history; otherwise every 6 months Postoperatively: yearly but individualize	TTE + CTA or MRA at baseline and 6 months No TAA: TTE yearly and CTA or MRA every 2 years First TAA diagnosis: TTE and CTA or MRA yearly if stable (< 0.3 cm/year) and < 4.5 cm, other-wise every 6 months and refer to surgeon
Turner syndrome	Baseline TTE and CTA or MRA If no TAA or dissection risk factors, repeat every 5–10 years	If no TAA: TTE every 3–5 years for low risk, MRA every 3–5 years for moderate risk, and MRI every 1–2 years for high risk	Index dimensions by body surface area; if indexed diameter > 2 cm/m², repeat yearly	TTE + CTA or MRA at baseline and 6 months Index dimensions by body surface area No TAA: TTE yearly and CTA or MRA every 2 years Indexed diameter > 2 cm/m²: yearly MRA or CTA and refer to surgeon
Familial TAA	No specific recommendations after initial imaging TTE and CTA or MRA	No specific recommendations after initial imaging TTE and CTA or MRA	Follow plan for Marfan syndrome, but individualize	TTE + CTA or MRA at baseline and 6 months Follow plan for Marfan syndrome but individualize risk
Loeys-Dietz syndrome	Baseline and 6 months TTE and CTA or MRA, then yearly if stable Whole-body MRA	No specific recommendations after initial imaging TTE and CTA or MRA	Every 1–3 years depending on risk, every 6 months if progression	TTE + CTA or MRA at baseline and 6 months Yearly if low risk, < 4.0 cm and stable (< 0.3 cm/year), otherwise every 6 months and refer to surgeon
Ehlers-Danlos syndrome	No specific recommendations	No specific recommendations, individualize	No specific recommendations	TTE + CTA or MRA at baseline and 6 months No specific recommendation for surveillance

ACC = American College of Cardiology; AHA = American Heart Association; ASE = American Society of Echocardiography;
CTA = computed tomography angiography; EACVI = European Association of Cardiovascular Imaging; ESC = European Society of Cardiology;
MRA = magnetic resonance angiography; MRI = magnetic resonance imaging; TAA = thoracic aortic aneurysm; TTE = transthoracic echocardiography