Prognostic Significance of Aneurysm Sac Shrinkage After Endovascular Aneurysm Repair

Purpose: To investigate whether patients who develop aneurysm sac shrinkage following endovascular aneurysm repair (EVAR) have better outcomes than patients with a stable or increased aneurysm sac. Materials and Methods: The Healthcare Databases Advanced Search interface developed by the National Institute for Health and Care Excellence was used to interrogate MEDLINE and EMBASE. Thesaurus headings were adapted accordingly. Case-control studies were identified comparing outcomes in patients demonstrating aneurysm sac shrinkage after EVAR with those of patients with a stable or expanded aneurysm sac. Pooled estimates of dichotomous outcome data were calculated using the odds ratio (OR) and 95% confidence interval (CI). Meta-analysis of time-to-event data was conducted using the inverse-variance method; the results are reported as a summary hazard ratio (HR) and 95% CI. Summary outcome estimates were calculated using random-effects models. Results: Eight studies were included in quantitative synthesis reporting a total of 17,096 patients (8518 patients with sac shrinkage and 8578 patients without sac shrinkage). The pooled incidence of sac shrinkage at 12 months was 48% (95% CI 40% to 56%). Patients with aneurysm sac shrinkage had a significantly lower hazard of death (HR 0.73, 95% CI 0.60 to 0.87), secondary interventions (HR 0.42, 95% CI 0.29 to 0.62), and late complications (HR 0.37, 95% CI 0.24 to 0.56) than patients with a stable or increased aneurysm sac. Furthermore, their odds of rupture were significantly lower than those in patients without shrinkage (OR 0.09, 95% CI 0.02 to 0.36). Conclusion: Sac regression is correlated to improved survival and a reduced rate of secondary interventions and EVAR-related complications. The prognostic significance of sac regression should be considered in surveillance strategies. Intensified surveillance should be applied in patients who fail to achieve sac regression following EVAR.