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Proposed Algorithm for Endovascular Aneurysm Repair Surveillance: A Call for Further Research on Personalized Surveillance

Long-term randomized clinical trial data have shown endovascular aneurysm repair (EVAR) to carry a higher risk of secondary intervention and aneurysm-related mortality than open repair.1 As a result, surveillance is considered an essential part of the endovascular management of abdominal aortic aneurysms. Controversy, however, remains among endovascular specialists around the modes and frequency of EVAR surveillance. There is limited evidence to suggest the superiority of one surveillance strategy over another, resulting in variability in surveillance practices across different vascular units nationally and internationally. Such variability is reflected in different recommendations between clinical practice guidelines.2,3 Surveillance is expected to detect 3 main potential complications, namely endoleak, sac growth, and graft migration, which are interrelated representing a closed network, for example, endoleak may result in sac growth, graft migration may cause an endoleak, or sac growth may cause graft migration (Figure 1). The ultimate goal is to identify such complications early, rectify problems, and prevent aneurysm rupture. Surveillance algorithms take into account risks of potential damage caused by imaging techniques, for example, contrast-induced nephropathy, the risk of developing EVAR-related complications, and cost. Experts in the field seem to be converging on the opinion that “one size doesn’t fit all.”2 For instance, a patient who shows significant sac shrinkage with no endoleak or migration may not benefit from frequent surveillance imaging, whereas a patient with sac expansion and no endoleak may require more intensive surveillance. We propose a surveillance algorithm that takes account of recommendations from the 2 major vascular society clinical practice guidelines2,3 and considers the most contemporary evidence, applying a color code, that is, red requiring intervention, yellow requiring further investigations or more intensive surveillance, and green raising no concerns (Figure 2).4 In this algorithm, after the 30-day computed tomography (CT) scan, we propose different paths based on the CT scan findings indicated by the color code, that is, ultrasound (US) surveillance (± abdominal X-ray) at 12 months if there is no endoleak or there is only a type II endoleak, further investigations with contrast-enhanced US or digital subtraction angiography (and subsequent treatment if necessary) if there is an indeterminate endoleak, or immediate treatment if the CT scan shows a type I or III endoleak. Following the 12-month US scan and in the absence of a malignant or indeterminate endoleak, the mode and frequency of surveillance is determined by the sac behavior and the presence of type II endoleak as follows: