Long-term clinical outcomes of EVAR within IFU compared to outside IFU

Background Endovascular aneurysm repair (EVAR) has been used worldwide to treat abdominal aortic aneurysm (AAA). Outcomes after EVAR between within instruction for use (IFU) and outside IFU are still controversial. We analyzed long term outcomes of EVAR within IFU compared to EVAR outside IFU and baseline clinical/anatomical characteristics that influence outcomes of EVAR. Methods We collected data from 766 patients (mean age 71.0 ± 12.5 years, male 90.2%) who underwent EVAR for infrarenal AAA between August 1997 and July 2021 at two centers in Korea. The primary endpoint was aneurysm related mortality (ARM) during follow up. The secondary outcomes were endoleak, reintervention and aneurysm sac enlargement. Results The mean AAA diameter is 59.0 ± 12.2 mm. The proportion of patients underwent EVAR outside IFU was 62.7% (n=466). Neck angle > 60 degree was the most common outside IFU criterion (n=210, 27.4%). The median clinical and imaging follow-up duration was 36.5 and 51.0 months, respectively. Total 110 patients (14.8%) had complications during follow up. The outside IFU group had more complications compare to the within IFU group (p=0.033). Overall mortality rate was 8.8% (n=60). ARM occurred in 0% of patients with EVAR within IFU and in 7 (1.5%) of patients with EVAR outside IFU (p=0.041), respectively. There was no significant difference in incidence of endoleak (28.5 vs. 23.1%, p=0.173), reintervention rate (8.4 vs. 9.3%, p=0.688) and aneurysm sac enlargement (23.6 vs. 23.4%, p=0.957) between patients underwent EVAR within IFU and outside IFU group. In multivariate analysis, proximal neck diameter > 28 mm was independent risk factor for ARM (HR, 9.132; 95% CI, 1.684 – 49.516, P=0.010). In addition, proximal neck angle > 60 degree was independent risk factor for endoleak (HR, 1.553; 95% CI, 1.042 – 2.314, P=0.031) and reintervention (HR, 2.297; 95% CI, 1.333 – 3.955, P=0.003). Neck length < 10 mm and neck diameter >28 mm were risk factors for aneurysm sac enlargement (HR, 4.363; 95% CI, 1.252 – 15.211, P=0.021 and HR, 3.148; 95% CI, 1.261 – 7.859, P=0.014). Age over 75 was also a risk factor for endoleak (HR, 2.491; 95% CI, 1.666 – 3.726, P=0.000) and aneurysm sac enlargement (HR, 3.150; 95% CI, 1.536 – 6.458, P=0.002). Conclusions Our study showed EVAR outside IFU is associated higher ARM compared to EVAR within IFU. In addition, neck angulation was risk factor for endoleak and reintervention. Clinicians should be caution when they perform EVAR outside IFU and select optimal patient for successful EVAR.