Conical Aortic Neck as a Predictor of Outcome after Endovascular Aneurysm Exclusion: Midterm Results

Abstract

Conical neck may affect endovascular aneurysm repair (EVAR) outcomes. The aim of this study was to present EVAR neck adverse events [endoleak type Ia (ET Ia) and graft migration], in patients with conical neck morphology compared to patients with non-conical necks. An additional analysis of the factors that may affect neck adverse events in patients with conical necks, during the first postoperative year, was executed. A retrospective analysis of prospective data was conducted, including patients that underwent elective EVAR, between 2017 and 2019. All patients completed the clinical and imaging follow-up of the initial 12months. Regarding imaging, all cases underwent computed tomography angiography (CTA), preoperatively, at the 1st and 12th month of follow-up. Preoperative and postoperative aneurysm anatomic characteristics (supra-renal and infra-renal aortic diameters, aneurysm diameter, neck angle, thrombus, and calcification) were recorded. Proximal neck was defined as the infrarenal aortic segment, with a diameter less than 30mm. Conical neck was any neck with a diameter increase ≥2mm per cm of length (from outer-to-outer aortic wall). The proximal 15mm of the neck length were considered the zone of endograft sealing. Migration was any ≥10mm caudal movement of the endograft, relative to its position detected at the CTA of the first month. Neck adverse events were defined as the composite event of ET Ia and migration. The cohort included 150 patients; 66 (44%) presented conical neck morphology. No significant difference was detected regarding the preoperative anatomic characteristics between the conical and non-conical groups. Only distal (15mm) neck diameter was wider in the conical group (P<0.001). Supra-renal active fixation was used in 63.3% of the total cohort; 59.5% in patients with non-conical necks and 68.2% in patients with conical morphology (P=0.275). Graft oversizing was 18.2% and 18.7% in the non-conical and conical group, respectively (P=0.248). Oversizing >20% was equal between groups [37.8% vs. 33.3%% (P=0.608) while oversizing ≥30% was more common among patients with conical necks (3.5% vs. 10.6%, P<0.001, 3.2 odds ratio, 95% confidence interval: 0.79, 12.91). Regarding ET Ia and migration, no difference was recorded between the groups. In a subanalysis among patients with conical necks, a lower graft migration rate was detected among patients with higher oversizing rate (P=0.037). EVAR may offer similarly good midterm outcomes in patients with conical and non-conical neck anatomy. An oversizing to the higher suggested rate may be preventive of graft migration during the first postoperative year in necks with conical morphology. Aggressive oversizing (>20%) do not offer any benefit regarding the prevention of adverse events among patients with conical necks.