Natural History of Common Iliac Artery Aneurysm in Men with Screening Detected Abdominal Aortic Aneurysms

Abstract

Introduction - A nationwide screening program for abdominal aortic aneurysm (AAA) targeting 65-year old men was introduced in 2006 and was fully implemented in 2015. The aim of the present study was to analyse the natural history of common iliac artery aneurysm (CIAA) in 65-year old men with a screening detected AAA or a subaneurysmal aorta (SAA). Methods - All 65-year old men were offered an abdominal aortic ultrasound examination in our county 2006-2014. An AAA was defined as an aortic diameter ≥30mm and a SAA as 25-29 mm. All subjects with an AAA or SAA had a simultaneous ultrasound examination of their common iliac arteries (CIA). A CIAA was defined as a CIA diameter ≥18 mm, according to the ISCVS/SVS Ad Hoc Committee. Results - Of 17774 men invited 15142 (85.2%) attended. A total of 197 (1.3%, 95% CI 1.1-1.5%) AAA and 228 (1.5%, 95% CI 1.3-1.7%) SAA were identified, of whom 415 (98%) had a reliable CIA ultrasound examination. The mean maximum CIA-diameter was 15 mm (range 8-60 mm). A total of 88 patients (35 SAA and 53 AAA) had a concomitant CIAA (21%; 95% CI 17-25%), 31% of which bilateral. Aortoiliac surgery was performed on 28 patients (32%), of which 19 (68%) on AAA indication, 5 (18%) on CIAA indication and 4 (14%) on combined AAA and CIAA indication. All five patients that underwent surgery based solely on CIAA size, were detected at initial AAA screening. No CIAA rupture was observed. In total 115 CIAAs were identified. These CIAAs together with 50 patients from an opportunistic screening cohort were used for growth rate estimation. CIAAs with one measurement (74), <6 months follow up (5) and measurement errors(18) were excluded. In total 68 CIAAs were analysed. Each patient had a range of 2 up to 11 measurements over time, with a mean number of observations of 5.2 (95% CI 4.6–5.8). The mean follow up time was 4.0 years (95% CI 3.5–4.6) and the mean growth rate was 0.6mm/year (95% CI 0.3 – 0.9). Data on co-morbidity, heredity and medication were collected, but no significant growth predictors could be identified. Conclusion - CIAA is relatively common in 65-year old men with a screening detected AAA or SAA. All CIAAs requiring surgery were detected upon initial AAA screening with ultrasound, marking the need of iliac assessment at the first examination. Most concomitant CIAAs in our material however, presented a slow growth rate, questioning the need of iliac examination at AAA follow up.