How should a middle‑aged to elderly adult with hypertension and atherosclerotic risk factors who has a thoracic aortic aneurysm involving the aortic arch and an intraluminal thrombus be evaluated and managed, including imaging, blood‑pressure control, medical therapy, and criteria for surgical or endovascular repair?

Management of Thoracic Aortic Arch Aneurysm with Intraluminal Thrombus

For a middle-aged to elderly adult with hypertension and atherosclerotic risk factors presenting with a thoracic aortic arch aneurysm and intraluminal thrombus, immediate referral to a high-volume multidisciplinary aortic center is mandatory, with surgical intervention indicated when diameter reaches ≥5.5 cm in asymptomatic patients or immediately if symptomatic, while aggressive medical management with beta-blockers and blood pressure control to <140/90 mmHg must be initiated regardless of size. 1, 2

Initial Diagnostic Evaluation

Imaging Protocol:

• CT angiography (CTA) is the gold standard for complete evaluation, requiring both non-contrast and contrast phases to assess thrombus burden, aneurysm dimensions, and suitability for intervention 3
• CTA must include the entire aorta from aortic sinuses through iliac bifurcation to evaluate extent of disease and plan vascular access 3
• ECG-gated CTA minimizes motion artifacts and provides precise definition of the aortic arch and ascending aorta 4
• MRI/MRA is reasonable for serial surveillance to minimize radiation exposure in stable patients 3, 2

Critical Assessment Points:

• Measure maximum diameter at seven predetermined aortic segments plus the site of maximum dilatation 5
• Document presence and extent of intraluminal thrombus, as thrombus presence accelerates aneurysm growth exponentially 5
• Evaluate for concurrent atherosclerotic disease, wall calcification, and involvement of branch vessels 3
• Assess landing zones (2-3 cm of normal diameter aorta without circumferential thrombus) for potential endovascular repair 3

Medical Management (Mandatory for All Patients)

Blood Pressure Control:

• Target blood pressure <140/90 mmHg (or <130/80 mmHg if diabetes or chronic kidney disease present) 2
• Beta-blockers are first-line therapy with target heart rate ≤60 beats per minute to reduce aortic wall stress 2
• Add ACE inhibitors or ARBs after achieving rate control to avoid reflex tachycardia 2
• Critical pitfall: Never initiate vasodilators before beta-blockade, as reflex tachycardia increases aortic wall stress 2

Atherosclerosis Risk Reduction:

• Statin therapy targeting LDL <70 mg/dL given atherosclerotic etiology 2
• Mandatory smoking cessation, as smoking is independently associated with accelerated aneurysm growth 5, 2
• Optimize lipid profile and control other cardiovascular risk factors 2

Surveillance Strategy

Imaging Frequency:

• Initial imaging at 1,3,6, and 12 months post-diagnosis to establish growth rate 2
• If stable after first year, annual imaging is appropriate for aneurysms <45 mm 3
• For aneurysms 50-55 mm, re-image every 6 months until intervention threshold reached 3
• If growth rate ≥3 mm/year, increase surveillance to every 6 months regardless of size 3

High-Risk Features Requiring Closer Monitoring:

• Presence of intraluminal thrombus (strongest predictor of accelerated growth) 5
• History of stroke or peripheral vascular disease 5
• Saccular morphology 3
• Growth rate ≥10 mm/year or ≥5 mm in 6 months 3

Surgical Intervention Criteria

Immediate Surgical Referral (Symptomatic):

• Any symptomatic patient requires immediate evaluation regardless of diameter, as symptoms (chest/back pain, hoarseness, dysphagia, dyspnea) indicate impending rupture 3, 1
• Aneurysms 6.0-6.5 cm carry 7% annual rupture risk 3, 2

Elective Intervention Thresholds (Asymptomatic):

• ≥5.5 cm diameter in low-risk patients with isolated arch aneurysm 3, 1, 2
• Lower thresholds apply if genetic syndrome present (not applicable to this atherosclerotic case) 1
• Growth rate >0.5 cm/year even if below size threshold 3

Treatment Approach Selection

Open Surgical Repair (Preferred for Arch Aneurysms):

• Open surgical replacement via median sternotomy with cardiopulmonary bypass is the gold standard for low-to-intermediate risk patients with arch involvement 1
• Requires hypothermic circulatory arrest with retrograde/antegrade cerebral perfusion for brain protection 1, 3
• Partial arch replacement with ascending aorta repair using right subclavian/axillary artery inflow is reasonable for proximal arch involvement 3
• Complete arch replacement indicated for extensive arch destruction or when arch is aneurysmal 3
• Cerebrospinal fluid drainage reduces spinal cord ischemia risk 1

Hybrid Approach (High Surgical Risk):

• For high-risk surgical candidates, hybrid repair combining supra-aortic debranching with TEVAR may be reasonable 1, 4
• Requires translocation of brachiocephalic vessels using branch grafts from proximal ascending aorta 3

Endovascular Considerations:

• Pure TEVAR not FDA-approved for isolated arch aneurysms 3
• Intentional left subclavian artery coverage occurs in ~50% of thoracic endografts; verify contralateral vertebral artery patency pre-operatively 3
• Risk of spinal cord ischemia increases to 10-12% if previous abdominal aortic repair versus 2% without 3

Critical Contraindications and Pitfalls

Absolute Contraindications to Endovascular Repair:

• Absence of adequate landing zones (need 2-3 cm normal diameter aorta) 3
• Aortic width exceeding largest available device (typically >10-15% oversizing limit) 3
• Severe atherosclerosis with heavy thrombus burden increases embolic stroke risk 3

Common Pitfalls to Avoid:

• Do not delay referral to specialized high-volume aortic centers once intervention criteria met, as arch aneurysms carry highest surgical complexity and mortality risk 1
• Do not assume isolated arch disease; most arch aneurysms result from adjacent pathology requiring comprehensive aortic imaging 1
• The presence of intraluminal thrombus mandates more aggressive surveillance given exponential growth acceleration 5
• Previous cerebrovascular events predict faster growth; adjust surveillance accordingly 5

Prognosis Without Intervention

• Aneurysms >5.6 cm have 46-74% rupture risk with two-year mortality >70% 6
• Rupture risk doubles with every 1 cm growth over 5 cm 3
• Median expansion rate 1.43 mm/year, but increases exponentially with diameter and presence of thrombus 5