Amount of Intraluminal Thrombus Correlates with Severe Adverse Events in Abdominal Aortic Aneurysms after Endovascular Aneurysm Repair

Background: The goal of this study is to verify whether the amount of intraluminal thrombus (ILT) within the aneurysm sac is associated with the outcomes of abdominal aortic aneurysm (AAA) after endovascular aneurysm repair (EVAR).Methods: This single-center retrospective study was conducted by reviewing all patients who underwent EVAR between January 2010 and June 2015. Patients with an infrarenal AAA who received elective EVAR and had available pre- and postoperative computed tomography angiographies were included for analysis. The amount of ILT was depicted as ILT percentage and was calculated by using the ILT volume divided by the total volume of infrarenal abdominal aorta. The optimal cutoff point of the ILT percentage was determined by a receiver operating characteristic curve. The ILT percentage was evaluated as a predictor of severe adverse events (SAEs) using univariate and multivariate Cox regression analyses.Results: A total of 184 patients with infrarenal AAA (male 151, female 33; mean age 72.2 +/- 7.7 years) were included. The mean ILT percentage of 184 AAA patients was 40.1% (range 1.6-79.3%). The estimated threshold of the ILT percentage was 51.6% for increased risk of SAEs after EVAR. Patients were divided into the low ILT group (ILT percentage <51.6%, n = 130) and the high ILT group (ILT percentage >= 51.6%, n = 54). The groups had similar comorbidities and anatomic characteristics, except that the high ILT group was more likely to have a larger maximal aneurysm diameter and a longer lowest renal bifurcation length. Compared with the low ILT group, the 4-year freedom from SAE rate was significantly lower for the high ILT group (54.8% vs. 86.1%, P < 0.01). Multivariate Cox regression analyses confirmed that an ILT percentage of 51.6% or greater was independently associated with SAEs after EVAR (hazard ratio = 2.90, P = 0.04).Conclusions: In our cohort, the amount of preoperative ILT is associated with the outcomes of elective EVAR. An ILT percentage of 51.6% or greater is an independent predictor of SAEs after EVAR.