Sac Shrinkage after Endovascular Aneurysm Repair: New Insights into Aneurysm Wall Degeneration and Loss of Elasticity

Endovascular aneurysm repair (EVAR) has markedly reduced perioperative morbidity and mortality in the management of abdominal aortic aneurysms. However, its long-term durability remains a concern because of sac expansion, endoleaks, and late rupture. Sac shrinkage serves as a key surrogate marker of procedural success, reflecting favorable remodeling and a lower risk of complications. Sac behavior after EVAR is determined by the interplay between intrasac pressure and aneurysm wall integrity. Although pressure reduction is essential, wall degeneration and stiffness critically influence remodeling outcomes. The presence of simple renal cysts, a localized manifestation of systemic connective tissue degeneration, has been associated with impaired sac shrinkage and may indicate unfavorable remodeling. Arterial stiffness, assessed by pulse wave velocity, also correlates with sac behavior: lower stiffness favors shrinkage, whereas higher stiffness is linked to expansion or lack of shrinkage. These findings suggest that sac remodeling is a multifactorial process not solely dependent on flow exclusion. Future prospective studies integrating artificial intelligence, vascular remodeling inhibition, and stent graft innovation are warranted to refine patient-specific risk stratification, guide individualized surveillance, and promote sac shrinkage, thereby improving outcomes after EVAR.