What is the recommended treatment for a stable 3 x 2.5 x 1.4 cm partially saccular aneurysm of the infrarenal abdominal aorta (AA) with an eccentric plaque?

Management of a Stable 3 x 2.5 x 1.4 cm Partially Saccular Infrarenal Abdominal Aortic Aneurysm with Eccentric Plaque

For a stable 3 x 2.5 x 1.4 cm partially saccular aneurysm of the infrarenal abdominal aorta with eccentric plaque, surveillance with duplex ultrasound every 3 years is recommended rather than immediate intervention.

Rationale for Surveillance

The management decision is based on several key factors:

1. Size threshold: The current aneurysm measures 3 x 2.5 x 1.4 cm, which is significantly below the intervention threshold of ≥5.5 cm for men or ≥5.0 cm for women 1.

2. Saccular morphology consideration: While the European Society of Cardiology (ESC) guidelines note that elective repair for saccular aneurysms ≥4.5 cm may be considered (Class IIb recommendation), this aneurysm is still well below this threshold at 3 cm 1.

3. Stability: The aneurysm is described as stable, indicating no rapid growth that would warrant more frequent monitoring or earlier intervention.

Surveillance Protocol

Based on the 2024 ESC guidelines, the following surveillance protocol should be implemented:

• Initial imaging modality: Duplex ultrasound (DUS) is recommended as the primary surveillance tool 1.
• Frequency: For AAA of 30-39 mm, surveillance every 3 years is recommended 1.
• Follow-up imaging: If DUS does not allow adequate measurement, cardiovascular computed tomography (CCT) or cardiovascular magnetic resonance (CMR) is recommended 1.

Risk Factor Management

While under surveillance, aggressive risk factor modification is essential:

1. Lipid management:

   • Target LDL-C <1.4 mmol/L (<55 mg/dL) with ≥50% reduction from baseline 1, 2
   • Statin therapy for all AAA patients 2

2. Blood pressure control:

   • Target SBP 120-129 mmHg if tolerated 2
   • Consider beta-blockers to reduce shear stress on the aortic wall 2

3. Smoking cessation:

   • Complete smoking cessation is essential as smoking accelerates AAA expansion by approximately 0.4 mm/year 2

4. Physical activity:

   • Moderate physical activity is beneficial 2
   • Avoid competitive sports and activities that cause blood pressure spikes 2

Monitoring for Progression

Certain findings during surveillance would warrant a change in management:

1. Growth rate: If aneurysm growth ≥5 mm in 6 months or ≥10 mm per year is detected, consider repair even if below standard size thresholds 1.

2. Size progression: If the aneurysm reaches 40-44 mm, increase surveillance frequency to every 12 months 1.

3. Symptom development: If the patient develops symptoms such as back pain, abdominal pain, or flank pain, immediate evaluation is required regardless of size 2.

Special Considerations for Saccular Morphology

The partially saccular morphology with eccentric plaque requires special attention:

• Saccular aneurysms may have higher rupture risk at smaller diameters than fusiform aneurysms 2.
• The eccentric plaque suggests atherosclerotic etiology, which research has shown can contribute to aortic wall weakening 3, 4.
• Studies have demonstrated that atherosclerotic plaque containing abundant thrombus and few calcifications may develop enlargement 5.

When to Consider Intervention

Intervention would be recommended if:

1. The aneurysm reaches ≥5.5 cm in diameter (men) or ≥5.0 cm (women) 1.
2. The saccular component reaches ≥4.5 cm 1.
3. Rapid growth is detected (≥10 mm/year or ≥5 mm/6 months) 1.
4. The patient develops symptoms attributable to the aneurysm 2.

Conclusion

For this stable 3 x 2.5 x 1.4 cm partially saccular infrarenal AAA with eccentric plaque, the evidence strongly supports surveillance rather than intervention. The surveillance protocol should include DUS every 3 years, with aggressive risk factor modification and vigilant monitoring for any changes in size, morphology, or symptom development.