Type II endoleak after endovascular aneurysm repair is a risk factor for late Type IA endoleak

Abstract: Background Endovascular repair for abdominal aortic aneurysm has been widely performed, and it has yielded more favorable short-term outcomes than open surgical repair. Endovascular repair is associated with endoleak, and several studies have reported risk factors for each type. However, the relationships between the different types of endoleaks have not been established. Methods A total of 394 patients who underwent endovascular repair of true abdominal aortic aneurysms at our institution between November 2006 and December 2022 were retrospectively analyzed. The follow-up period was at least six months. The patients were grouped based on the presence or absence of type II endoleak, and the influence of type II endoleak on the development of late type IA endoleak was determined. Results The patients had a mean age of 75.0 ± 7.6 years, and 339 were male. The median follow-up period was 5.7 years (range, 0.51–16.1 years). Type II endoleak was observed in 198 patients. No significant differences in the proximal neck anatomy were observed between the two groups. The incidence of late type IA endoleak was significantly higher in patients with type II endoleak (1.1%, 5.9%, and 19.4% versus 0.0%, 2.4%, and 2.4% at 1, 5, and 10 years, respectively, log-rank p=0.0005). The patients with type II endoleak had significant proximal neck shortening (p = 0.0004) and enlargement of the proximal neck diameter on the aneurysmal side (p < 0.0001). The pathway mediated by aneurysm sac enlargement was statistically significant based on the Bayesian mediation analysis adjusted for age and sex (posterior predictive p-value = 0.422). Conclusion Type II endoleak after endovascular repair is associated with an increased incidence of late type IA endoleak. The prevention and treatment of type II endoleak may improve long-term outcomes after endovascular repair.