Previous large registry studies demonstrated an association between early sac changes and late survival after AAA repair.(1,2) Early sac changes have the ability to be a marker in guiding post-EVAR follow-up schemes as prior studies demonstrated early aneurysm sac regression to be associated with lower rates of complications and reinterventions too. However, these studies were limited to single or high-volume centers.(3-5) In this study we used the VQI-Medicare-linked database to examine the association of these early sac changes with mortality, reinterventions and rupture.

We identified all patients who underwent EVAR for intact AAA between 2003-2018 in the VQI with linkage to Medicare claims for long-term outcomes. We required that patients have an imaging study at 1-year postoperatively (+6months) in order to assess aneurysm sac changes. Aneurysm sac behavior was defined per the SVS guidelines: stable sac (<5mm change), sac regression (≥5mm decrease), and sac growth (≥5mm increase). Outcomes included eight-year mortality, reintervention rates, and rupture after one-year imaging. We assessed outcomes with Kaplan-Meier methods and Cox regression, adjusting for demographics, comorbidities, aortic diameter, urgency status(elective/symptomatic), and center/physician procedural volume.

Of 31,185 EVAR patients, 16,102 (52%) had an imaging study at 1 year and were included in this study. At 1 year, 44% of sacs remained stable, 49% of sacs regressed, and 6.2% displayed sac growth. Following risk-adjustment, compared with a stable sac at one-year, sac regression was associated with lower 8-year mortality (49% vs. 53%/HR: 0.92[95%CI:0.85-0.99], p=.036) (Figure 1A), reintervention rates (11% vs. 16%/Hazard Ratio[HR]: 0.58[95%CI:0.50-0.68], p<.001) (Figure 1B), and rupture rates (2.0% vs. 4.0%/HR: 0.45[95%CI:0.29-0.69], p<.001) (Figure 1C). Conversely, compared with a stable sac, sac growth was associated with higher 8-year mortality (64% vs. 53%/HR: 1.31[95%CI: 1.14-1.51], p<.001), and reintervention rates (33% vs. 16%/HR: 1.98[95%CI:1.57-2.51], p<.001), but similar risk of rupture (7.2% vs. 4.0%/HR: 1.61[95%CI:0.88-2.96], p=.12).

After infrarenal EVAR, sac regression is associated with lower risk of mortality, reinterventions, and rupture, whereas sac growth is associated with higher risk of mortality, reinterventions, and a trend toward higher rupture. Future studies are needed to determine how to improve one-year sac regression, and whether it is safe to extend follow-up intervals for these patients.

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