Abstract No. 215 Endovascular Embolization versus Observation in Congenital Renal Arteriovenous Malformations

To describe the presentation of patients with congenital renal arteriovenous malformations (AVMs) and outcomes associated with observation versus endovascular embolization. Retrospective imaging and chart review of patients at a single center with renal AVMs and no inciting procedure or trauma. Yakes class, renal artery-vein diameter ratio, and symptoms were used to describe AVMs. Procedural imaging and follow up data were assessed to identify adverse events and potential advantages of endovascular intervention over observation. 14 patients had congenital renal AVM, 8 were asymptomatic at diagnosis. 9 patients were observed and 5 were treated with endovascular embolization. Of those 5, 3 had symptoms attributable to AVMs. 4 of 5 procedures (80%) had complete nidus/fistula embolization. All 3 symptomatic patients (100%) had resolution post-procedurally, including with incomplete embolization, with no major complications or adverse events. Of the 9 patients without intervention, 3 were symptomatic. 4 of 9 (44%) had adverse outcomes and 2 of 9 (22%) had AVM rupture requiring nephrectomy. Both ruptured patients had type I AVMs and 2 with worsening medical morbidity had type IIb AVMs. Congenital renal AVMs, despite growing quite large, can be subclinical and may be overlooked when found incidentally. Given the risk of clinically significant symptoms or rupture, endovascular embolization should be considered for all renal AVM. In this small study, the ratio of adverse events in the non-intervention group was concerning. Notably, the intervention group had clinical improvement and no adverse events. As both patients with AVM rupture had Yakes type I AVMs (direct AV fistula), type I AVMs may deserve special consideration for intervention. Further investigation is needed to determine the value of AVM traits, such as renal vessel size, in stratifying AVM risk.