What imaging and referrals are recommended for a patient with atherosclerosis ectasia of the thoracic aorta and an electrocardiogram (ECG) showing normal sinus rhythm (NSR) with leftward axis?

Management of Atherosclerotic Ectasia of the Thoracic Aorta

For a patient with atherosclerotic ectasia of the thoracic aorta, obtain CT angiography (CTA) of the chest, abdomen, and pelvis with ECG-gating as the primary imaging modality, and refer to cardiology for risk stratification and medical management, with cardiothoracic surgery consultation if the ascending aorta measures ≥5.0 cm or descending aorta ≥4.0 cm. 1

Primary Imaging Recommendation

CTA is the preferred definitive imaging modality for evaluating thoracic aortic ectasia, offering near-universal availability, short examination time, and diagnostic accuracy with sensitivities up to 100% and specificities of 98-99%. 1, 2 The protocol should include:

• ECG-gating to provide motion-free images of the aortic root and ascending aorta 1
• Extension to abdomen and pelvis to assess the entire aorta, as thoracic aortic pathology frequently extends distally 1
• Arterial phase and delayed contrast imaging with thin-section acquisition timed to peak arterial enhancement 1
• Standardized diameter measurements perpendicular to the longitudinal flow axis at defined anatomic locations to avoid tangential measurement errors 1, 3

The leftward axis on ECG suggests possible left ventricular hypertrophy from chronic hypertension, which commonly accompanies aortic atherosclerosis and requires correlation with imaging findings. 1

Alternative Imaging Considerations

MRA (magnetic resonance angiography) may be preferred for patients requiring repeated surveillance imaging to avoid cumulative radiation exposure. 1 MRA provides equivalent diagnostic accuracy to CTA and should include:

• ECG-gated contrast-enhanced sequences for the aortic root and ascending aorta 1
• Black-blood imaging sequences to assess aortic wall thickness and distinguish atherosclerotic plaque from intramural hematoma 1
• Coverage from chest through pelvis 1

Transthoracic echocardiography (TTE) should be performed to evaluate the aortic root (which TTE visualizes accurately), assess for concomitant structural heart disease including bicuspid aortic valve or left ventricular hypertrophy, and measure left ventricular ejection fraction. 1, 4 However, TTE fails to consistently visualize the tubular ascending thoracic aorta and is inadequate as the sole imaging modality for thoracic aortic ectasia. 1

Critical Measurements and Surveillance Parameters

Measure aortic diameter at standardized locations using centerline-of-flow technique: 1, 3

• Ascending aorta ≥5.0 cm warrants surgical consultation 3
• Descending thoracic aorta ≥4.0 cm warrants surgical consultation 3
• Growth rate ≥3 mm/year is considered high-risk and requires more frequent surveillance 3

Calculate the aortic size index (aortic diameter in cm divided by body surface area in m²), as this may be more predictive than absolute diameter alone in determining intervention thresholds. 1

Specialist Referrals

Cardiology Referral (Required)

Refer to cardiology for: 5, 6, 7

• Cardiovascular risk factor optimization including aggressive blood pressure control (target <130/80 mmHg), lipid management, diabetes control, and smoking cessation 3, 5
• Beta-blocker therapy to reduce aortic wall stress in patients with aortic dilation 3
• Coronary artery disease assessment, as thoracic aortic atherosclerosis strongly correlates with significant CAD (75.9% of patients with CAD have aortic atherosclerosis) 6, 7
• Complex aortic plaques in the descending aorta are the strongest predictor of CAD (odds ratio 5.4) 7

Cardiothoracic Surgery Referral (Conditional)

Refer to cardiothoracic surgery if: 1, 3

• Ascending aorta diameter ≥5.0 cm 3
• Descending thoracic aorta diameter ≥4.0 cm 3
• Rapid growth rate (≥3 mm/year) 3
• Symptomatic disease (chest pain, back pain, hoarseness, dysphagia) despite optimal medical management

Surveillance Imaging Schedule

Establish surveillance intervals based on maximal aortic diameter: 3

• 30-39 mm: Every 3 years
• 40-44 mm: Annual surveillance
• 45-49 mm: Every 6 months
• ≥50 mm: Consider intervention

Use the same imaging modality (CTA or MRA) for serial measurements to ensure consistency and avoid measurement variability between techniques. 1

Important Clinical Caveats

Atherosclerotic ectasia represents a generalized vascular disease process, not an isolated finding. 8 The presence of thoracic aortic atherosclerosis carries a 12% risk of recurrent stroke within one year and up to 33% risk of stroke or peripheral embolism. 9

Document the extent and location of calcification if cardiac surgery is anticipated, as severe calcification ("porcelain aorta") significantly increases stroke risk during cardiac procedures and may require specialized surgical techniques including no-touch approaches or alternative cannulation sites. 5

The normal sinus rhythm with leftward axis suggests evaluate for left ventricular hypertrophy on echocardiography, which commonly accompanies chronic hypertension and aortic disease. 1 This finding does not alter the imaging or referral strategy but reinforces the need for aggressive blood pressure management.

Distinguish aortic ectasia from aneurysm: ectasia represents diffuse enlargement typically 1.5 times normal diameter, while aneurysm represents focal dilation ≥5.0 cm (ascending) or ≥4.0 cm (descending). 3 Both require surveillance but aneurysms have higher rupture risk and lower intervention thresholds.