The Effect of Abdominal Aortic Aneurysm Size on Endoleak, Secondary Intervention and Overall Survival Following Endovascular Aortic Aneurysm Repair

Endurant Stent Graft for Treatment of Abdominal Aortic Aneurysm Inside and Outside of the Instructions for Use for the Proximal Neck: A 14-Year, Single-Center Experience

Aim: To assess the medium and long-term performance of the Endurant stent graft in a cohort of consecutive patients treated with this device for an abdominal aortic aneurysm (AAA) both inside and outside of the instructions for use (IFU) and to find factors influencing the outcomes. Methods: Our observational, retrospective, single-center study included all patients who consecutively underwent endovascular aneurysm repair with the Endurant stent graft from February 2009 to January 2023. Patients with an AAA to treat according to current guidelines were included. Patients were divided into two groups: Group 1 inside of the IFUs and Group 2 outside of the IFUs for the proximal aortic neck. Patients were followed up after the procedure with computed angiography tomography, ultrasound examination, and interviews. Aneurysm-related mortality, procedure-related reinterventions, and type IA and III endoleaks were considered primary endpoints. Secondary endpoints included aneurysmal sac variations and graft thrombosis. Results: A total of 795 patients were included, 650 in Group 1 and 145 in Group 2; 732 were males, and the mean age was 74 ± 8. Anamnestic baseline did not differ between the two groups. Neck length, width, and angulation were different between the two groups (all p < 0.001). A total of 40 patients had a ruptured AAA, while 56 were symptomatic. At a mean follow-up of 43 ± 39 months, aneurysm-related mortality was less than 1%, and 82 endoleak (10.5%) were observed. Overall endoleak rate and type 1A endoleak, as well as procedure-related reintervention, were significantly more frequent in Group 2. Sac regression of at least 5 mm was observed in 65.9% of cases. AAAs larger than 60.5 mm carried a higher risk of endoleak (HR: 1.025; 95% CI: 1.013-1.37; p < 0.001) and proximal necks shorter than 13.5 mm carried a higher type 1A risk (HR: 0.890; 95% CI: 0.836-0.948; p < 0.001). Patients without chronic obstructive pulmonary disease and taking lipid-lowering drugs had an overall more consistent sac-shrinking rate. Conclusions: The Endurant stent graft proves safe and reliable. Out-of-IFU treatment has poorer medium and long-term outcomes. Some conditions influence medium and long-term reintervention risk and sac behavior. Patients with bigger aneurysms, proximal necks shorter than 13.5 mm, and chronic obstructive pulmonary disease should be more carefully evaluated during follow-up. Consistent follow-up is in keeping low aneurysm-related mortality. Personalized risk profiles and peri and postoperative management strategies are needed.

Identification of Clinical Heterogeneity and Construction of Prediction Models for Novel Subtypes in Patients with Abdominal Aortic Aneurysm: An Unsupervised Machine Learning Study

BACKGROUND

Abdominal aortic aneurysm (AAA) is one of the most common diseases in vascular surgery. Endovascular aneurysm repair (EVAR) can effectively treat AAA. It is essential to accurately classify patients with AAA who need EVAR.

METHODS

We enrolled 266 patients with AAA who underwent EVAR. Unsupervised machine learning algorithms (UMLAs) were used to cluster subjects according to similar clinical characteristics. To verify UMLA's accuracy, the operative and postoperative results of the 2 clusters were analyzed. Finally, a prediction model was developed using binary logistic regression analysis.

RESULTS

UMLAs could correctly classify patients based on their clinical characteristics. Patients in Cluster 1 were older, had a higher BMI, and were more likely than patients in Cluster 2 to develop pneumonia, chronic obstructive pulmonary disease, and cerebrovascular disease. The aneurysm diameter, neck angulation, diameter and angulation of bilateral common iliac arteries, and incidence of iliac artery aneurysm were significantly higher in cluster 1 patients than in cluster 2. Cluster 1 had a longer operative time, a longer length of stay in the intensive care unit and hospital, a higher medical expense, and a higher incidence of reintervention. A nomogram was established based on the BMI, neck angulation, left common iliac artery (LCIA) diameter and angulation, and right common iliac artery (RCIA) diameter and angulation. The nomogram was evaluated using receiver operating characteristic curve analysis, with an area under the curve of 0.933 (95% confidence interval, 0.902-0.963) and a C-index of 0.927.

CONCLUSIONS

Our findings demonstrate that UMLAs can be used to rationally classify a heterogeneous cohort of patients with AAA effectively, and the analysis of postoperative variables also verified the accuracy of UMLAs. We established a prediction model for new subtypes of AAA, which can improve the quality of management of patients with AAA.

Outcomes and Cost-Analysis of Open Versus Endovascular Abdominal Aortic Aneurysm Repair in a Developing Country: A 15-year Experience at a Tertiary Medical Center

BACKGROUND

Endovascular aortic aneurysm repair (EVAR) has become the most common procedure for treating abdominal aortic aneurysms based on multiple studies conducted in the western world. The implication of such findings in developing countries is not well demonstrated. The objective of this study was to compare medical outcomes and costs of EVAR and open surgical repair (OSR) in a developing country.

METHODS

This is a retrospective study of all patients undergoing elective abdominal aortic aneurysm repair between 2005 and 2020 at a tertiary medical center in a developing country. Medical records were used to retrieve demographics, comorbidities, and perioperative complications. Medical records were also used to provide data on the need of reintervention, date of last follow-up, and mortality.

RESULTS

The study included a total of 164 patients. Median follow-up time was 41 months. The mean age was 69.9 +/- 7.84 years and 90.24% (n = 148) of patients were males. Regarding long-term mortality outcomes, no significant difference was detected between both groups; OSR patients had a survival rate of 91.38% and 74.86% at 5 and 10 years, compared to 77.29% and 56.52% in the EVAR group (P value = 0.10). Both groups had comparable long-term reintervention rates (P value = 0.334). The OSR group was charged significantly less than the EVAR group ($27,666.35 vs. $44,528.04, P value = 0.008).

CONCLUSIONS

OSR and EVAR have comparable survival and reintervention outcomes. Unlike what was reported in developed countries, patients undergoing OSR in countries with low hospital stay costs incur lower treatment costs.