Measurement of Aneurysm Volumes After Endovascular Aortic Aneurysm Repair as a Predictive Factor of Postoperative Complications

To the Editors:

We read with great interest the publication of Oliveira-Pinto et al ¹ on aneurysm volume changes after endovascular aortic aneurysm repair (EVAR). In this study, the authors compared aneurysm sac shrinkage after EVAR between patients who had ruptured infrarenal abdominal aortic aneurysm (AAA) and those who had intact AAA. Interestingly, they found that aneurysm sac shrinkage decreased more in patients who had ruptured AAA vs intact AAA during the first year (−26.3% vs −11.9%, p<0.001). In addition, patients with early sac shrinkage had a lower incidence of complications after the 1-year examination with an adjusted hazard ratio (HR) of 0.59 (95% CI 0.39 to 0.89, p=0.01). While aneurysm sac shrinkage has been identified as a predictive factor of postoperative outcomes in elective EVAR,^2,3 this study presents the interest to specifically address its significance during ruptured AAA endovascular repair. The authors hypothesized that accelerated sac shrinkage in ruptured AAA could be related to increased wall fragility that may favor depressurization and regression of the sac. ¹ However, the exact pathophysiological mechanisms involved still remain to be explored. Altogether, these results point to the interest to evaluate aneurysm sac shrinkage during the postoperative follow-up.

The measurement of aneurysm diameter is commonly used in clinical practice during the follow-up, but the method can fail to detect significant changes of the aneurysm volumes. ⁴ Volumetric measurement of AAA remains the most reliable method to assess sac shrinkage, ⁵ but it requires manual segmentation, which is tedious, time-consuming, and subject to intra- and interoperator variability. Recent advances in imaging segmentation have been achieved over the past few years ⁶ and automatic software enabling the measurement of AAA volumes are being developed, some using techniques derived from artificial intelligence.^7,8 Automated segmentation and measurement of AAA volumes and diameters would be very useful in practice to alleviate this burdensome task for the surgeon, gain time, improve robustness, and reproducibility of the measures. Although these methods need to be tested in larger cohorts of patients to evaluate their generalizability and their concordance with the ground truth provided by human-trained operators, major advances in imaging analysis are to be expected within the next few years and this may help improve the management and the follow-up of patients with AAA.