In this issue, Zetterval et al. suggest a significantly greater risk of renal complications after endovascular aneurysm repair (EVAR) with suprarenal fixation, based on an analysis of a large cohort of patients with abdominal aortic aneurysm (AAA), drawn from the National Surgical Quality Improvement Project (NSQIP) in North America.
1
Renal injury following endovascular AAA repair is well recognised,
2
and there is increasing anxiety regarding the longer-term impact of EVAR on renal function.3
Concerns that acute kidney injury (AKI) after EVAR may be greater for patients treated with endografts with suprarenal fixation are not new. Indeed, evidence that these devices are associated with significantly higher rates of renal infarction is well established.
4
, 5
However, despite this, both previous meta-analyses have not demonstrated robust evidence of an increased risk of renal injury after suprarenal fixation when compared with patients managed with infrarenal devices.4
, 5
The NSQIP dataset used in the study by Zetterval et al. highlights both the strengths and weaknesses of registry data. On a positive note, a large number of patients were available to help answer the study aims: 3587 collected from a contemporary 3 year period using modern day endografts.
1
However, the study also highlights some of the limitations of large registry data sets. The overall low rate of renal complications described in this study is not in keeping with contemporary literature,
6
where rates of renal injury of up to 20% have been reported. This largely reflects the definition of renal complications used in the NSQIP, a rise in creatinine of 2 mg/dL or new dialysis, both of which should be considered severe AKI. The multiple different definitions of AKI in the literature following AAA repair have hampered robust meta-analysis and the standardisation of reporting of AKI,7
either following KDIGO guidelines or utilising the Aneurysm Renal Injury Score, should be encouraged.7
, The second major weakness of this study is that it is highly likely there is significant selection bias related to aortic morphology. The patients treated with suprarenal endografts may well have had shorter and more hostile neck anatomy and this alone may have accounted for the higher renal complication rates rather than the graft configuration per se. The NSQIP does not record any anatomical data and therefore the authors were unable to make any adjustments for these vital confounding factors. This underlines the importance of identifying important variables at the outset when large registries are established. The UK National Vascular Registry collects limited anatomical data on AAA cases, including neck length, diameter, and angulation
9
; if the NSQIP had done the same, simple adjustment for these confounders would have allowed the authors to present data that would have stood up to more robust scrutiny.VSQIP. Available at: https://www.vsqip.org.uk.
It is also important to note that this study only reports on 30 day outcomes, and does not address the longer-term impact of suprarenal fixation on renal function.
However, despite the weaknesses described above there appears to be mounting circumstantial evidence that suprarenal endograft fixation is associated with a greater acute renal insult than infrarenal fixation. Further studies comparing the two techniques in cohorts matched for both demographics and aortic morphology are clearly needed.
References
- Comparison of renal complications between endografts with suprarenal and infrarenal fixation.Eur J Vasc Endovasc Surg. 2017; 54: 5-11
- Renal consequences of endovascular abdominal aortic aneurysm repair.J Endovasc Ther. 2008; 15: 73-82
- Long-term renal function after endovascular aneurysm repair.Clin J Am Soc Nephrol. 2015; 10: 1930-1936
- Suprarenal endograft fixation and medium-term renal function: systematic review and meta-analysis.J Vasc Surg. 2008; 47: 1364-1370
- Characterizing the evolution of perioperative outcomes and costs of endovascular abdominal aortic aneurysm repair.J Vasc Surg. 2015; 62: 1134-1139
- A systematic review and meta-analysis indicates underreporting of renal dysfunction following endovascular aneurysm repair.Kidney Int. 2015; 87: 442-451
- Renal Dysfunction after EVAR: time for a standard definition.J Endovasc Ther. 2013; 20: 331-333
- Clinical practice guideline for acute kidney injury.Kidney Int. 2012; 2: 1-138
VSQIP. Available at: https://www.vsqip.org.uk.
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Published online: April 10, 2017
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- Comparison of Renal Complications between Endografts with Suprarenal and Infrarenal FixationEuropean Journal of Vascular and Endovascular SurgeryVol. 54Issue 1
- PreviewSurgeons have multiple grafts options available for the endovascular treatment of abdominal aortic aneurysm (EVAR), and some hypothesize that suprarenal fixation endografts may result in higher rates of renal complications than infrarenal endografts. This study aimed to compare the outcomes of contemporary suprarenal and infrarenal endografts.
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