Impact of Intraoperative Branch Embolization for Type 2 Endoleak Prevention During Endovascular Abdominal Aortic Repair

BACKGROUND: Endovascular abdominal aortic repair (EVAR) has a significantly higher revision rate than open repair, primarily due to type 2 endoleak (2EL). Although 2ELs are considered benign, late open conversion (LOC) due to the expansion of the aneurysm diameter of the 2EL is a concern in the mid- and long-term. In this study, we investigated the impact of embolization of the inferior mesenteric artery (IMA) or lumbar artery (LA) at the time of the initial EVAR and its long-term outcomes. METHODS: Between April 2008 and December 2021, 743 EVAR procedures for abdominal aortic aneurysms were performed at our institution. The patients were divided into 2 groups at the time of initial surgery, namely, 215 and 528 patients in the embolization (Group E) and nonembolization (Group N) groups, respectively. Branch embolization was performed in patients with an IMA diameter ≥3 mm and LA diameter ≥2 mm on preoperative computed tomography. Re-embolization with EL was performed in patients with a diameter enlargement ≥10 mm, and LOC was performed in patients with continued enlargement ≥15 mm after re-embolization. The mean follow-up period was 7.0 years. RESULTS: The mean number of branch embolizations was 2.3 ± 1.1. Intraoperatively, the operative time, fluoroscopy time, irradiation dose, and contrast medium use were significantly higher in Group E than in Group N. There was a significant difference between the 2 groups regarding shrinkage (Group E versus Group N: 45.6% versus 37.3%; P = 0.03) and enlargement (Group E versus Group N: 9.3% vs. 19.5%; P < 0.001) of the aneurysm diameter by > 5 mm after EVAR. In the mid- and long-term, the avoidance rate of 2EL reintervention was significantly lower in Group E at 5 years (93.5% vs. 88.6%) and 10 years (87.5% vs. 76.4%; P = 0.04). LOC prevention was 5 years; Group E: 100% vs. 96.9% for Group N and 10 years; Group E: 98.8% vs. 92.5% for Group N, significantly lower in Group E (P = 0.02). CONCLUSIONS: The impact of branch embolization at the time of the initial EVAR is believed to prevent enlargement of the aneurysmal sac and LOC. However, prolonged operation time, increased radiation exposure, and the use of contrast medium have been debated. To improve the long-term results of EVAR, embolisms of both the IMA and LA are required.