Endovascular Repair of Abdominal Aortic Aneurysms: Analysis of Aneurysm Volumetric Changes at Mid-Term Follow-Up

Abstract

To evaluate the volumetric changes in abdominal aortic aneurysms (AAA) after endovascular AAA repair (EVAR) in 24 months of follow-up. We evaluated the volume modifications in 63 consecutive patients after EVAR. All patients underwent strict duplex ultrasound and computed tomography angiography (CTA) follow-up; when complications were suspected, digital subtraction angiography was also performed. CTA datasets at 1, 6, 12, and 24 months were post-processed through semiautomatic segmentation, to isolate the aneurysmal sac and calculate its volume. Maximum transverse diameters (Dmax) were also obtained in the true axial plane, Presence and type of endoleak (EL) were recorded. A statistical analysis was performed to assess the degree of volume change, correlation with diameter modifications, and significance of the volume increase with respect to ELs. Mean reconstruction time was 7 min. Mean volume reduction rates were 6.5%, 8%, and 9.6% at 6, 12, and 24 months follow-up, respectively. Mean Dmax reduction rates were 4.2%, 6.7%, and 12%; correlation with volumes was poor (r = 0.73-0.81). ELs were found in 19 patients and were more frequent (p = 0.04) in patients with higher preprocedural Dmax, The accuracies of volume changes in predicting ELs ranged between 74.6% and 84.1% and were higher than those of Dmax modifications. The strongest independent predictor of EL was a volume change at 6 months < or = 0.3% (p = 0.005), although 6 of 19 (32%) patients with EL showed no significant AAA enlargement, whereas in 6 of 44 (14%) patients without EL the aneurysm enlarged. The lack of volume decrease in the aneurysm of at least 0.3% at 6 months follow-up indicates the need for closer surveillance, and has a higher predictive accuracy for an endoleak than Dmax.