PRe-emptive abdominal aortic aneurysm sac Embolization during endoVascular Aortic Repair (PREVAR) for infrarenal abdominal aortic aneurysm—study protocol for a randomized controlled trial

Abdominal aortic aneurysm (AAA) is a potentially lethal condition if left untreated. AAA growth is a predictor of rupture as well as decreased survival. Minimally invasive infrarenal endovascular aortic repair (EVAR) is the primary option for AAA treatment. One of the most common complications after EVAR is the presence of type 2 endoleaks (T2ELs), i.e., continued retrograde perfusion of the aneurysm sac by aortic side branches, typically the lumbar arteries. In many cases, a T2EL prevents optimal aneurysm exclusion and is associated with continued aneurysm growth. Thus, a low but persistent risk of rupture and a high rate of reinterventions remain an issue/concern in the presence of T2ELs. In addition, failure of aneurysm sac shrinkage even without concomitant endoleak is associated with decreased long-term survival. Pre-emptive as well as postoperative selective side branch occlusion to prevent or treat T2ELs is time-consuming and technically demanding with a low technical and clinical success rate. Therefore, perioperative, nonselective embolization of the aneurysm sac during EVAR has been proposed to prevent T2EL and promote sac shrinkage (PREVAR—Clinical Trial NCT05575570). Patients scheduled for EVAR at the Department of Vascular Surgery, Rigshospitalet Copenhagen University Hospital, The Heart Center, Denmark, are offered inclusion in this study. Patients are randomized to infrarenal EVAR (control) or infrarenal EVAR plus sac embolization with Shape Memory plugs (SMP) (intervention). The plugs are based on a resorbable scaffolding and a small radiopaque marker causing minimal imaging artifacts on computed tomography angiography (CTA). The number of plugs is individually calculated based on aneurysm sac flow volume. Postoperative follow-up (FU) is performed after 3 months, 1 year, and 5 years with both contrast-enhanced ultrasound (CEUS) and 3-phase CTA (without contrast, arterial phase, and venous phase). AAA sac volume change is the primary endpoint. Incidence of T2EL, reintervention rate, and long-term survival are the secondary endpoints. The study is terminated after the final patient has completed the 5-year FU. EVAR has revolutionized AAA treatment since its introduction. In the short term, outcomes are superior to open aortic repair in anatomically suitable candidates. However, the high incidence of T2ELs and failure of AAA sac shrinkages associated with reinterventions and decreased survival in many patients. Preliminary data on intraoperative AAA sac embolization during EVAR seems to promote sac shrinkage. SMP plugs are tested and CE marked (Conformité Européenne) for embolization treatment but the effect of aneurysm sac embolization during EVAR is poorly known. This randomized study investigates the effect of aneurysm sac embolization with SMP plug material in a single-center setting. Clinical Trial, PREVAR—Clinical Trial NCT05575570, registered October 12, 2022, https://clinicaltrials.gov/study/NCT05575570 .