From the Guidelines
Rupture risk in Endovascular Aneurysm Repair (EVAR) is best estimated through regular surveillance imaging, particularly with contrast-enhanced CT scans, combined with assessment of multiple risk factors, as outlined in the 2022 ACC/AHA guideline for the diagnosis and management of aortic disease 1. The most reliable approach involves measuring aneurysm sac diameter and volume changes over time, with an increase of 5mm or more in maximum diameter or persistent sac enlargement being significant predictors of rupture risk.
- Key factors to evaluate include:
- Presence of endoleaks, especially type I and III, which are significant risk factors for rupture, as they may lead to aneurysm sac enlargement 1
- Device migration greater than 10mm
- Structural device failures
- Patient-specific factors such as hypertension, smoking status, and COPD
- Contrast-enhanced CT scans are the gold standard imaging modality, ideally performed at 1 month post-procedure, 12 months, and then annually thereafter if stable, as recommended by the American College of Radiology 1. Patients with multiple risk factors require more frequent monitoring, potentially every 6 months rather than annually. The integration of these measurements with clinical assessment provides the most comprehensive rupture risk estimation, allowing for timely intervention when concerning changes are identified. Proper risk estimation is crucial as post-EVAR rupture carries a mortality rate of approximately 60-70%, significantly higher than primary repair of intact aneurysms. It is also important to note that duplex ultrasound, while useful for measuring aortic aneurysm sac diameter and detecting type I and III endoleaks, has limitations in detecting stent migration, fracture, or new noncontiguous aneurysms, and thus should be used in conjunction with other imaging modalities 1.
From the Research
Rupture Risk Estimation in EVAR
The estimation of rupture risk in Endovascular Aneurysm Repair (EVAR) is crucial for the management and follow-up of patients with abdominal aortic aneurysms. Several studies have investigated the factors that influence rupture risk after EVAR.
Factors Influencing Rupture Risk
- Aneurysm enlargement without detectable endoleaks is a significant factor in estimating rupture risk after EVAR 2.
- The annual rate of rupture in patients with aneurysm enlargement of >8 mm after EVAR, without detectable endoleaks, is <1% in the first 4 years, but accelerates to 7.5% up to 13.6% in the years thereafter 2.
- The presence of type Ia endoleaks does not necessarily increase the risk of rupture, and EVAR may reduce the risk of aneurysm rupture despite persisting type Ia endoleaks 3.
Imaging Techniques for Rupture Risk Estimation
- Computed tomographic angiography (CTA) is the most commonly used imaging technique for surveillance after EVAR, but it has limitations, such as radiation exposure and potential for missed diagnosis 4, 5.
- Contrast-enhanced ultrasound (CEUS) is a promising alternative to CTA, with high sensitivity for detecting endoleaks and potential for reducing radiation exposure 6.
- Other imaging techniques, such as magnetic resonance angiography, ultrasonography, and digital subtraction angiography, also have a role in endoleak detection and management 4, 5.
Clinical Implications
- Regular follow-up with imaging surveillance is essential for detecting endoleaks and estimating rupture risk after EVAR 4, 5.
- The choice of imaging technique should be individualized based on patient factors, such as renal function and allergy to contrast agents 5.
- Further research is needed to determine the optimal imaging strategy for rupture risk estimation after EVAR 5.