The relationship of preoperative thrombus load and location to the development of type II endoleak and sac regression.

Background: Few studies have specifically correlated the amount of thrombus in the aneurysm sac and the presence of type II endoleaks (TIIE). This study examined the correlation of preoperative thrombus load and location to the incidence of TIIE and late sac regression.

Methods: Prospectively collected data from 266 endovascular aneurysm repair (EVAR) patients were analyzed. Maximum thrombus thickness (MTT) and percentage of the circumference of the aortic wall lined by thrombus (thrombus-lined aneurysm circumference [TLAC]) were determined from preoperative computed tomography angiography (CTA) images at four levels: neck, maximum abdominal aortic aneurysms (AAA) diameter (zone B), zone A (between neck and zone B), and zone C (between zone B and aortic bifurcation). The number of aortic side branches (ASB) was also recorded (inferior mesenteric artery [IMA], accessory renals, lumbar, and middle sacral). Logistic regression was used to determine the association of TIIE with each variable.

Results: Thirty-three (12%) early and 32 (13%) late TIIE were noted at a mean follow-up of 22 months (range, 1-87 months). The mean MTT at zone B was 19.7 mm in patients without early TIIE and 18.8 mm in patients without late TIIE vs 14.4 and 17.2 mm in patients with early and late TIIE (P = .0137 and P = .444, respectively). The mean percentage of TLAC was 76% and 75% vs 65% and 64% in patients without vs with early and late TIIE (P = .0329 and P = .044, respectively). There was no correlation of early and late TIIE and thrombus location by zones. The IMA was patent in 7% and 7% of patients without early and late TIIE vs 16% and 15% with TIIE (P = .0367 and P = .077, respectively). The mean number of ASB in patients without (early and late) TIIE was 5.8 and 5.6 vs 5.8 and 7 with endoleak (P = .932 and P = .001, respectively). Univariate analysis showed the following variables decreased the incidence of early TIIE: MTT for zone B (odds ratio [OR] 0.79 for 5-mm increase; P = .014), MTT zone A (OR, 0.78; P = .028), MTT zone C (OR, 0.82; P = .043), and percentage of TLAC (OR, 0.88 for 10% increase; P = .036). For late TIIE: percentage of TLAC (OR, 0.88 for 10% increase; P = .048), and ASB (OR, 1.39 for each additional vessel; P = .001). A multiple regression model showed only ASB (OR, 1.34; P = .009) was a predictor for late TIIE. Four of five patients (80%) with late sac expansion vs 24 of 208 (12%) without expansion had late TIIE (P = .001).

Conclusions: MTT, percentage of TLAC, number of ASB, and patent IMA influenced early TIIE; however, only the number of ASB influenced late TIIE.