Systematic review and meta-analysis on the incidence and prognosis of sac regression after endovascular aneurysm repair

INTRODUCTION: The primary objective of this systematic review and meta-analysis was to assess the incidence and prognosis of sac regression following endovascular aneurysm repair (EVAR), focusing on mortality (all-cause and aneurysm-related), aneurysm rupture, endoleaks, and secondary interventions. EVIDENCE ACQUISITION: A systematic literature search was performed across PubMed, Scopus, Web of Science, and Google Scholar up to December 2024. Randomized trials, cohort studies, and case-control studies involving patients who underwent standard EVAR for abdominal aortic aneurysms (AAA) were included. The studies were included only if they compared patients with sac regression versus those without during follow-up. The Newcastle-Ottawa Scale (NOS) was used for quality assessment. The data were synthesized using a random-effects model to calculate relative risks (RR) for outcomes of interest. EVIDENCE SYNTHESIS: A total of 18 observational studies involving 25,984 patients were included. Sac regression was reported in 12,195 patients (46.9% [95% CI: 46.3%, 47.5%]), although with varying definitions of shrinkage through studies. Pooled analyses showed that sac regression was significantly associated with reduced all-cause mortality (RR=0.68 [95% CI: 0.59, 0.78], P<0.001) and aneurysm rupture (RR=0.38 [95% CI: 0.15, 0.97], P=0.044). Sac regression also correlated with lower rates of endoleaks (RR=0.45 [95% CI: 0.33, 0.62], P<0.001) and secondary interventions (RR=0.40 [95% CI: 0.31, 0.52], P<0.001). CONCLUSIONS: Aneurysm sac regression is a valuable prognostic marker after EVAR. It is associated with better clinical outcomes, including reduced mortality and complications. Standardizing the definition and assessment of sac regression is essential for more consistent findings. Further prospective studies and randomized trials are needed to confirm these results and better understand the mechanisms behind sac regression.