Simple renal cyst and its association with sac shrinkage after endovascular aneurysm repair for abdominal aortic aneurysms

Abstract Objective Patients with abdominal aortic aneurysm (AAA) frequently have simple renal cyst (SRC), a common manifestation of connective tissue degeneration. This study aimed to determine whether SRC is a risk factor for failure of sac shrinkage after endovascular aneurysm repair (EVAR). Methods Between October 2013 and May 2017, there were 155 consecutive patients with an infrarenal AAA or a common iliac artery aneurysm who underwent EVAR with the GORE C3 Excluder (W. L. Gore & Associates, Flagstaff, Ariz) at Tokyo Medical University Hospital. All these patients were registered in a prospectively maintained database. Any kidney lesion >5 mm in diameter, with no evidence of contrast enhancement or septation and with low attenuation, was defined as SRC. A change in sac size of >5 mm from baseline was considered significant. The patients were divided into those with SRC and those without SRC, and sac shrinkage at 1 year and 2 years was compared. The presence of SRC was assessed with respect to being a risk factor for failure of sac shrinkage at 1 year using univariate and multivariable logistic regression analysis. Results The patients were divided into two groups: those with SRC (92 patients [59.0%]) and those without SRC (63 patients [41.0%]). At 1 year and 2 years, significant differences were observed in the proportion of sac shrinkage between patients with SRC and those without SRC (19.2% vs 42.4% [P = .003] and 19.6% vs 53.3% [P = .001], respectively). Patients with SRC showed significantly less sac shrinkage than those without SRC at 1 year and 2 years (−2.0 ± 5.5 mm vs −4.4 ± 6.2 mm [P = .002] and −1.8 ± 6.3 mm vs −6.4 ± 8.6 mm [P = .005], respectively). Multivariable analysis demonstrated that SRC (odds ratio, 0.28; 95% confidence interval, 0.12-0.63; P = .002) and initial sac size (odds ratio, 1.05; 95% confidence interval, 1.01-1.09; P = .027) were positive and negative risk factors for sac shrinkage, respectively. Conclusions The presence of SRC is a risk factor for failure of sac shrinkage after EVAR. This suggests that AAA in patients with SRC has a more degenerated wall than in those without SRC. The property of the aneurysm wall may be associated with sac shrinkage after EVAR.