الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Outcomes of endovascular repair (EVAR) of abdominal aortic aneurysm (AAA) are influenced by the pre-operative aneurysm morphology. There is no universally accepted system for the objective classification of adverse features, partly because there is no standardized protocol for their assessment. The aims of this study were; to define the reproducibility of a protocol for the analysis of infra-renal aortic aneurysm morphology for clinical and research purposes, and to provide a contemporary account of clinical outcomes following EVAR in an experienced endovascular unit.
Methods
First, a protocol for the comprehensive assessment of pre-operative infra-renal AAA morphology was developed. Four observers performed morphological measurements on pre-operative computed tomography angiography (CTA) for 50 patients scheduled for EVAR using software that enabled 3D image reconstruction. One observer performed repeated measurements. The intra and inter-observer variability was calculated for all parameters and measurement time for all anatomical features was assessed. Then, after validation of the protocol, the morphology of the infra-renal AAA, for the patients who had EVAR in the period from 2004 to 2010, was retrospectively assessed. The postoperative clinical outcomes for those patients were prospectively studied. Morphological compliance with manufacturer’s instructions for use (IFU) was established using 3-dimensional CT data. The primary outcome measures were all-cause and aneurysm-related mortality, postoperative rupture, re-intervention and sac expansion. These adverse events were reported using Kaplan-Meier survival analysis, with comparison within or outside IFU by the log-rank test.
Results
The variability study showed that, aorto-iliac diameter, length, volume, area and tortousity index measurements had good inter and intra observer agreement. Aortic neck angles and aorto-iliac angles measurements displayed high intra and inter-observer repeatability coefficients (RC% = 28 – 43% and 29 – 61% respectively). Calcification measurements had the highest variability within and between observers, RC% = 39 – 65% and 44 – 96%, respectively. The measurement protocol was completed in a mean of 105 minutes (range 55 – 420 min). The outcomes study showed that, 478 patients aged 75 +/- 7 years had aneurysm diameter of 66 +/- 12mm. Median follow-up was 44 months (range 11-94). 198/478 (42%) were compliant with IFU. The 30-day mortality was 10/478 (2.1%) patients; 9/455 (2.0%) elective and 1/23 (4.3%) non-elective; aneurysm-related mortality was 0.897 deaths per 100 person-years and all-cause mortality was 8.558 deaths per 100 person-years, with significantly lower survival outside IFU (p=0.012). There were two ruptures, 0.138 per 100 person-years, of whom one died. There were 6.120 re-interventions per 100 person-years, with no difference outside IFU (p=0.136). Primary sac expansion occurred in 6.721 per 100 person-years and secondary sac expansion in 4.142 per 100 person-years.
Conclusions
Accurate 3D analysis of AAA morphology can be performed reliably within a reasonable time. Measurements that relied on consistent anatomical landmarks were most reproducible. Automated methods are likely to be more suitable for certain measurements. In long-term outcomes, EVAR was performed with less aneurysm-related mortality than demonstrated in early randomised controlled trials, and with lower sac expansion rates than reported from image repositories. Data from those studies should be applied to current practice with caution.
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