A systematic review summarizing local vascular characteristics of aneurysm wall to predict for progression and rupture risk of abdominal aortic aneurysms

Objective: At present, the rupture risk prediction of abdominal aortic aneurysms (AAAs) and, hence, the clinical decision making regarding the need for surgery, is determined by the AAA diameter and growth rate. However, these measures provide limited predictive information. In the present study, we have summarized the measures of local vascular char-acteristics of the aneurysm wall that, independently of AAA size, could predict for AAA progression and rupture. Methods: We systematically searched PubMed and Web of Science up to September 13, 2021 to identify relevant studies investigating the relationship between local vascular characteristics of the aneurysm wall and AAA growth or rupture in humans. A quality assessment was performed using the ROBINS-I (risk of bias in nonrandomized studies of interventions) tool. All included studies were divided by four types of measures of arterial wall characteristics: metabolism, calcification, intraluminal thrombus, and compliance. Results: A total of 20 studies were included. Metabolism of the aneurysm wall, especially when measured by ultra-small superparamagnetic iron oxide uptake, and calcification were significantly related to AAA growth. A higher intraluminal thrombus volume and thickness had correlated positively with the AAA growth in one study but in another study had correlated negatively. AAA compliance demonstrated no correlation with AAA growth and rupture. The aneurysmal wall characteristics showed no association with AAA rupture. However, the metabolism, measured via ultra-small super-paramagnetic iron oxide uptake, but none of the other measures, showed a trend toward a relationship with AAA rupture, although the difference was not statistically significant. Conclusions: The current measures of aortic wall characteristics have the potential to predict for AAA growth, especially the measures of metabolism and calcification. Evidence regarding AAA rupture is scarce, and, although more work is needed, aortic wall metabolism could potentially be related to AAA rupture. This highlights the role of aortic wall characteristics in the progression of AAA but also has the potential to improve the prediction of AAA growth and rupture.

Automated summary

Currently, the prediction of abdominal aortic aneurysm (AAA) rupture risk and clinical decision making for surgery is primarily based on AAA diameter and growth rate, which provide limited predictive information. This study summarizes measures of local vascular characteristics of the aneurysm wall that can predict AAA progression and rupture independently of AAA size. The results show that metabolism and calcification of the AAA wall are significantly related to AAA growth, while intraluminal thrombus and compliance are not correlated with AAA growth and rupture. There is also limited evidence regarding the association of aortic wall characteristics with AAA rupture, but metabolism measured by ultra-small superparamagnetic iron oxide uptake shows a potential trend of relationship with AAA rupture.