Anatomic Characteristics and Natural History of Renal Artery Aneurysms During Longitudinal Imaging Surveillance

Abstract

Renal artery aneurysms (RAA) are uncommon and rates of growth and/or rupture are unknown. Limited evidence, therefore, exists to guide clinical management of RAA, particularly those that are small and asymptomatic. To further characterize the natural history of RAA, we studied anatomic characteristics and changes in diameter during imaging surveillance. Patients evaluated for native RAA at a single institution over a three-year period (July 2010-July 2013) were identified and analyzed retrospectively. Patients with two or more cross-sectional imaging studies (computed tomography or magnetic resonance imaging) more than 1 month apart were included. Demographic and clinical data were collected from medical records and anatomic data (including aneurysm diameter, calcification, and location) were obtained from images. Aneurysm growth over time was analyzed using plots and Wilcoxon signed rank tests. Fifty-two aneurysms in 44 patients were analyzed. Median follow-up was 17.5 months (IQR, 8.1, 34.2 months); 70.5% of patients were female and mean age at initial presentation was 60.4 ± 9.5 years; and 75.0% of patients had hypertension. Imaging studies demonstrated a 20.5% prevalence of nonrenal abdominal aneurysms and 18.2% had multiple RAA. Most RAA were located at the main renal artery bifurcation and had some degree of calcification. Mean initial aneurysm diameter was 16.3 ± 6.3 mm. Median annualized growth rate was 0.03 mm (IQR, −0.16, 0.42 mm) (P = .34). 13.5% of RAA were repaired electively and no RAA ruptures occurred. Risk of short-term RAA growth or rupture was low. These findings suggest that annual (or less frequent) imaging surveillance is safe in the majority of patients and do not support pre-emptive repair of asymptomatic, small diameter RAA.