Definition of Type II Endoleak Risk Based on Preoperative Anatomical Characteristics

Purpose: To define the risk for type II endoleak (EII) after endovascular aneurysm repair (EVAR) based on preoperative anatomical characteristics. Methods: Between January 2008 and December 2015, 189 patients (mean age 78.4 +/- 7.6 years; 165 men) underwent standard EVAR. Mean aneurysm diameter was 5.7 +/- 0.7 cm and mean volume 125.2 +/- 45.8 cm(3). Patients were assigned to the at-risk group (n=123, 65%) when at least one of the following criteria was present: patency of a >3-mm inferior mesenteric artery (IMA), patency of at least 3 pairs of lumbar arteries, or patency of 2 pairs of lumbar arteries and a sacral artery or accessory renal artery or any diameter patent IMA; otherwise, patients were entered in the 'low-risk" group (n=66, 35%). EII rates and freedom from EII reintervention were compared using Kaplan-Meier curves. Preoperative clinical and anatomical characteristics were evaluated for their association with EII and EII reinterventions using multiple logistic regression analysis; results are presented as the odds ratio (OR) and 95% confidence interval (CI). Results: Freedom from endoleak was lower in the at-risk group compared with the low-risk group at 36 months after EVAR (p=0.04). Freedom from EII-related reinterventions was significantly lower in the at-risk group (80% vs 100%, p=0.001) at 48 months. Based on the multiple regression analysis, the at-risk group had a higher likelihood of both EII (OR 9.91, 95% CI 2.92 to 33.72, p<0.001) and EII-related reinterventions (OR 9.11, 95% CI 1.06 to 78.44, p=0.04). These criteria had 89.4% (95% CI 83.9% to 93.2%) sensitivity and 48.0% (95% CI 40.7% to 55.3%) specificity for EII; sensitivity and specificity for EII reintervention were 100% (95% CI 93.8% to 100%) and 38.8% (95% CI 31.9% to 46.2%). Within the at-risk group, a sac thrombus volume <35% was an additional predictor for both EII (OR 5.21, 95% CI 1.75 to 15.47, p=0.003) and EII-related reinterventions (OR 8.33, 95% CI 2.20 to 31.51, p<0.002). Conclusion: The selection criteria effectively discriminated between low-risk patients and patients at risk for EII and associated reinterventions. A thrombus volume <35% was an additional predictor for EII and EII-related reintervention among patients at risk. These criteria may be useful for preemptively selecting patients who may benefit from EII prevention procedures or a more aggressive surveillance protocol.