Impact of Infrarenal Neck Thrombus in Endovascular Aortic Aneurysm Repair on Proximal Seal and Type Ia Endoleak.

Abstract

Endograft instructions for use often list infrarenal aortic neck thrombus as a contraindication to endovascular aortic repair (EVAR), yet supporting evidence is limited. This study assessed the impact of neck thrombus on proximal seal and its association with type Ia endoleak and secondary intervention. A multicentre, retrospective, observational cohort study of consecutive patients who underwent elective EVAR for degenerative infrarenal abdominal aortic aneurysm was performed at three high volume hospitals in the Netherlands. Aortic morphology and endograft outcomes were analysed. Patients with infrarenal neck thrombus (≥ 2 mm thick and ≥ 25% circumference) were compared with those without. Shortest apposition length (SAL) was measured on post-operative computed tomography angiography. In the thrombus group, SAL was measured both including (SALTh) and excluding (SAL) stent apposition to the thrombus. Thrombus volume was measured before and after surgery. Kaplan-Meier analysis determined type Ia endoleak free and secondary intervention free survival. Among 310 patients (median follow up 4.28 years; interquartile range 1.37, 5.91 years), 91 (29.4%) had neck thrombus. Baseline characteristics were similar. On the first post-operative computed tomography angiogram, the thrombus group had a lower median SAL (17.6 mm vs. 23.0 mm, p < .001), but SALTh was comparable with the SAL in the no thrombus group (24.1 mm vs. 23.0 mm, p = .93). At five years, type Ia endoleak free survival was 92.6% in the thrombus group vs. 95.4% in the no thrombus group (p = .24). Secondary intervention free survival was 83.6% vs. 80.9% (p = .39). SAL increased over time in both groups, whereas thrombus volume decreased or resolved in all patients with thrombus. As neck thrombus volume diminishes over time, the proximal seal length increases, similar to that in patients without neck thrombus. In this midterm analysis, no statistically significant differences in type Ia endoleak free survival and secondary intervention free survival were observed between the thrombus and no thrombus groups. EVAR may not be contraindicated in patients with neck thrombus.