Impact of Early Sac Regression on Postendovascular Aneurysm Repair Midterm Outcomes

This study aims to identify predictors of aortic sac regression after endovascular aneursym repair (EVAR) and to evaluate the impact of early sac regression and these factors on adverse events such as endoleak, reintervention, and late mortality.

Retrospective analysis of 383 consecutive patients undergoing EVAR (2019-2025) at a single centre. Sac regression was defined as ≥5 mm decrease in maximum diameter or ≥10% volume reduction. Follow-up included computed tomography angiography to 3 years (or Doppler ultrasound/noncontrast CTA in renal impairment). Binary logistic regression identified predictors; Cox regression and Kaplan-Meier assessed late mortality, endoleak, and reintervention.

Median follow-up was 25 months (max 99). Sac regression occurred in 293 patients (76.5%). Nonregression was associated with older age (P = 0.04), dual antiplatelet therapy (P < 0.001), larger inferior mesenteric artery diameter (>3 mm; P = 0.04), and more patent lumbar arteries (P = 0.06). Nonregressors had significantly higher rates of all endoleak types, reinterventions, and longer hospital stays (P < 0.05). No aneurysm-related mortality occurred in the regression group (versus 1 case). Volume change showed superior area under the curve for predicting endoleak (0.927 vs. 0.852) and reintervention compared with diameter change. Multivariable predictors of nonregression included age, dual antiplatelet use, neck length, and inferior mesenteric artery diameter.

Sac regression was strongly associated with markedly improved midterm outcomes, including significantly lower rates of all endoleak types, reinterventions. Advanced age, dual antiplatelet therapy use, shorter neck length, and larger inferior mesenteric artery diameter emerged as independent predictors of failure to regress. Volume-based assessment outperformed diameter-based measurement in predicting sac changes more sensitively. These findings support the integration of volumetric monitoring into risk-stratified surveillance protocols, particularly for stabilized sacs and emphasize the value of individualized follow-up strategies guided by both sac regression status and volumetric changes, to further improve long-term outcomes following EVAR.