(Background) The issue of long-term outcome associated with type 2 endoleak (T2EL) after endovascular abdominal aneurysm repair (EVAR) has been discussed internationally in recent years. Not only the inferior mesenteric artery (IMA) but also the lumbar artery (LA) is considered a non-negligible cause of T2EL, and the effectiveness of preemptive aneurysmal branch embolization has been reported. At our hospital, we have been actively performing embolization of both the IMA and LA. We have been working on two-stage EVAR, in which embolization and EVAR are performed on separate days, due to concerns about prolonged operation time, increased use of contrast media, and increased radiation exposure caused by performing both procedures simultaneously with EVAR.

(Subjects and Methods) 435 patients underwent scheduled EVAR between January 2013 and December 2023 were divided into three groups: Group E (EVAR only without coil embolization), Group I (only IMA with coil embolization), and Group IL (IMA + LA coil embolization). In principle, LA embolization was performed on all LAs arising from the aneurysm by preoperative CT, and in the case of 2-stage EVAR, patients were hospitalized for IMA and LA coil embolization in advance and discharged from the hospital and readmitted the following month.Eligible patients were classified into (group E/I/IL) = (260/80/95), and 52 of the IL group were in the 2-stage group. We evaluated the rate of persistent T2EL after 6 months postoperatively and the reduction of aneurysm diameter. And also we analyzed operative time, contrast media dose and  radiation doze.

(Results) Eligible patients were classified into (group E/I/IL) = (260/80/95), and 52 of the IL group were in the 2-stage group. The number of patients with persistent T2EL after 6 months postoperatively was (group E/I/IL)=(55 (21.2%)/12 (15.0%)/5 (5.3%)). The reduction of aneurysm diameter was (group E/I/IL) = (72 (27.7%)/30 (37.5%)/58 (61.1%)). The rate of persistent T2EL  is significantly lower in the IL group and a high reduction rate was achieved in the IL group. There is no T2EL in 2 stage group. Regarding operative time, in the simultaneous group, it was 328 ± 105.2 minutes, while in the 2-stage group, coil time: 155 ± 45.2 minutes, EVAR time: 120 ± 20.9 minutes, and a reduction was also observed in the total time between the 2 procedures. The total contrast dose was (simultaneous group/2-stage group)=195±152.2 ml/141±25.6 ml, and the radiation doze was (simultaneous group/2-stage group)= 2320±720.5 mGy/1875.6±361.2 mGy, showing a trend toward a decrease in the 2-stage group. The embolization rate of the lumbar artery was 65.3% in the simultaneous group and 85.9% in the 2-stage group, with a statistically significant difference.

(Conclusion) This study reported the clinical outcomes of a single-center 2-stage EVAR preceded by IMA and LA embolization. Consistent with previously reported findings, embolization of the aneurysmal branch  led to a decrease in T2EL, a reduction in the expansion of the aneurysmal diameter, and the outcomes were satisfactory. In keeping with this clinical outcome, our two-stage EVAR strategy is useful because it reduces operative time, contrast media use, and radiation exposure. The two-stage approach alleviates emotional stress for the surgeon, assistants, nurses, and other staff involved. This is attributed to the shorter time required to complete the initial embolization compared to simultaneous EVAR and the elimination of the need to initiate EVAR immediately after embolization.2-stage EVAR preceded by aneurysmal branch embolization is effective in suppressing T2EL, shortening the operation time, and reducing the amount of contrast media used and radiation exposure, making it a useful treatment strategy that is expected to improve long-term outcomes while maintaining a minimally invasive approach. We would like to discuss and educate the public about two-stage EVAR not only to eliminate T2EL, but also to reform the way of working in EVAR treatment.