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

ObjectivePatients 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).MethodsBetween 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.ResultsThe 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.ConclusionsThe 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.