Predictors of early aortic neck dilatation after endovascular aneurysm repair with EndoAnchors

Abstract

Objective: Dilatation of the aorta within the proximal neck after endovascular aneurysm repair (EVAR) can be associated with late endoleaks and migration. This study was designed to identify predictors of early neck dilation in patients undergoing EVAR with Heli-FX EndoAnchors (Medtronic, Santa Rosa, Calif) measured perioperatively to 1 year at different longitudinal levels of neck length.

Methods: The study group of Aneurysm Treatment Using the Heli-FX Aortic Securement System (ANCHOR) comprises 257 consecutive patients prospectively enrolled between April 2012 and September 2014 undergoing EVAR with Heli-FX EndoAnchor implantation at 38 investigational sites. Only patients undergoing EndoAnchor implantation at the time of the initial EVAR were included (primary treatment arm). Aortic diameter was measured at the suprarenal level and at three levels within the proximal neck. Neck dilatation was assessed in 209 patients with adequate computed tomography imaging at baseline and 1 month and in 62 patients at 1 month and 1 year (mean, 11.9 ± 4.0 months). Multivariable analyses were performed to identify independent predictors of perioperative (baseline to 1 month) and early postoperative (1 month to 1 year) aortic dilation at each level; analyses included 6 candidate variables, 6 clinical, and 14 anatomic run in eight models (one at each of the four aortic levels for both time frames).

Results: The mean aortic neck dilation at 1 month was 0.2 ± 1.7 mm, 0.7 ± 2.2 mm, and 0.9 ± 3.6 mm at 0 mm, 5 mm, and 10 mm below the lowest renal artery, and 0.0 ± 1.5 mm at the suprarenal level. From 1 month to 1 year, neck dilatation was 0.5 ± 1.6 mm, 0.4 ± 1.5 mm, 0.2 ± 1.8 mm, and -0.3 ± 1.1 mm at the same four levels, respectively. Dilatation of ≥3 mm at level 5 mm distal to the lowest renal artery was observed in 26 patients (12.5%) from preoperative to 1 month and in 5 patients (8.1%) between 1 month and 1 year. Multivariable regression identified several variables predictive of perioperative (preoperative to 1 month) neck dilatation: baseline neck diameter, mural calcium (protective), and endografts with a suprarenal stent. Neck dilatation between 1 month and 1 year was associated with baseline neck diameter, neck length (protective), neck angulation, device oversizing, number of EndoAnchors implanted (protective), and endografts with a suprarenal stent.

Conclusions: Aortic diameter and graft oversizing appear to be independent risk factors for early aortic neck dilatation. EndoAnchors have a protective effect on neck dilatation at their usual level of deployment.