Abstract
Aortic neck dilatation (AND) occurs after endovascular aneurysm repair (EVAR) with self expanding stent grafts (SESs). Whether it continues, ultimately exceeding the endograft diameter leading to abdominal aortic aneurysm (AAA) rupture, remains uncertain. Dynamics, risk factors, and clinical relevance of AND were investigated after EVAR with standard SESs. All intact EVAR patients treated from 2000 to 2015 at a tertiary institution were included. Demographic, anatomical, and device related characteristics were investigated as risk factors for AND. Outer to outer diameters were measured at a single standardised aortic level on reconstructed computed tomography (CT) images. A total of 460 patients were included (median follow up 5.2 years, interquartile range [IQR] 3.0, 7.7 years; CT imaging follow up 3.3 years, IQR 1.3, 5.4). Baseline neck diameter was 24 mm (IQR 22, 26) and increased 11.1% (IQR 1.5%, 21.9%) at last CT imaging. Endograft oversizing was 20.0% (IQR 13.6, 28.0). AND was greater during the first year (5.2% [IQR 0, 11.7]) decreasing subsequently (two to four years to 1.4%/year [IQR 0.0, 4.5%], p ≤ .001) and was associated with suprarenal fixation endografts (t value = 7.9, p < .001) and oversizing (t value = 4.4, p < .001). AND exceeding the endograft was 3.5% (95% CI 2.2% – 4.8%) and 14.4% (95% CI 11.0% – 17.8%) at five and eight years, respectively. Excessive AND was associated with baseline neck diameter (OR 1.2/mm, 95% CI 1.05 – 1.41) while the Excluder endograft had a protective effect (OR 0.15, 95% CI 0.04 – 0.58). Excessive AND was associated with type 1A endoleak (HR 3.3, 95% CI 1.1 – 9.7) and endograft migration > 5 mm (HR 3.1, 95% CI 1.4 – 6.9). AND after EVAR with SES is associated with endograft oversizing and radial force but decelerates after the first post-operative year. Baseline aortic neck diameter and suprarenal stent bearing endografts were associated with an increased risk of AND beyond nominal stent graft diameter. However, it remains unclear whether patient selection, differences in endograft radial force or the suprarenal stent are accountable for this difference.
Highlights
Abdominal aortic aneurysm (AAA) management has been revolutionised by endovascular aneurysm repair (EVAR) owing to its lower procedural morbidity and mortality than open repair.[1,2] the risk of complications following EVAR increases over time, making understanding of the mechanisms of EVAR failure crucial to improving clinical outcomes.[3]
It is often described that the infrarenal sealing zone progressively dilates following EVAR when self expandable stent grafts (SESs) are used.4e6 it is unknown whether this process stops when the SES radial force on the sealing zone diminishes, as the nominal diameter of the oversized endograft is reached, or if it continues jeopardising the proximal seal and putting the patient at risk of type 1A endoleak and AAA rupture
It was found that for most patients, the rate at which it developed progressively decreased over follow up until the oversized endograft approximated to its nominal diameter and the influence of endograft radial force on the aortic neck progressively reduced
Summary
Abdominal aortic aneurysm (AAA) management has been revolutionised by endovascular aneurysm repair (EVAR) owing to its lower procedural morbidity and mortality than open repair.[1,2] the risk of complications following EVAR increases over time, making understanding of the mechanisms of EVAR failure crucial to improving clinical outcomes.[3] A durable proximal seal is vital to sustain clinical success. It is often described that the infrarenal sealing zone progressively dilates following EVAR when self expandable stent grafts (SESs) are used.4e6 it is unknown whether this process stops when the SES radial force on the sealing zone diminishes, as the nominal diameter of the oversized endograft is reached, or if it continues jeopardising the proximal seal and putting the patient at risk of type 1A endoleak and AAA rupture. The risk factors and clinical implications of proximal neck dilatation were investigated
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