Post-EVAR aneurysm sac shrinkage is prognostically favorable, but does not justify withholding follow-up

One of the main drawbacks of endovascular aortic aneurysm repair (EVAR) compared to open aortic surgery is the possibility of developing endoleaks and secondary aneurysm rupture, requiring frequent imaging follow-up. This study aims to identify prognostic factors that could be incorporated in follow-up protocols, which might lead to better personalized, lower cost and safe EVAR follow-up.

A retrospective study was performed including all patients who underwent elective EVAR from January 2000 to December 2015. Follow-up data were gathered by reviewing medical files for radiographic imaging. Linear and logistic regressions were used to assess predictive factors for aneurysm shrinkage.

In 361 patients, aneurysm sac shrinkage of 10 mm or more was measured in 152 (42.1%) patients. Patients with ≥10-mm aneurysm shrinkage had fewer endoleaks (4.3% vs. 24.6%, P<0.0001) and fewer re-interventions for endoleak (3.0% vs. 10.1%, P=0.007). Aneurysm sac shrinkage was correlated with the absence of endoleak development (OR 0.36, 95% CI 0.19-0.66, P=0.001). In patients who had achieved ≥10-mm shrinkage of the aneurysm sac, no further significant growth was seen, compared to 38 (15.3%) patients who did not attain size reduction (P<0.001).

Once patients achieve ≥10-mm aneurysm sac shrinkage, they are less prone to developing subsequent aneurysm growth and have significantly lower risk of requiring surgery for endoleaks. However, a small number of patients remain at risk of requiring endoleak surgery after aneurysm shrinkage. Therefore, we would not recommend ceasing life-long imaging follow-up after significant aneurysm sac shrinkage, though it might be safe to increase the interval of follow-up.