Impact of renal artery diameter and bridging stent length on renal outcomes of patients treated by multibranch endovascular aortic repair.

Abstract

Branched endovascular aortic repair (BEVAR) has been increasingly used as a treatment option for thoracoabdominal aortic aneurysms, but the risk of renal artery (RA) branch occlusion remains a concern. The aim of this study was to evaluate the effect of RA diameter and stent length on renal outcomes after BEVAR. Clinical data from consecutive patients enrolled in two prospective, nonrandomized, physician-sponsored investigational device exemption studies between 2017 and 2025 were reviewed. Patients treated by BEVAR using patient-specific or off-the-shelf company-manufactured devices with at least one RA directional branch were included. All RA branches were treated with Viabahn (W. L. Gore & Associates, Inc) self-expandable and/or balloon-expandable stent grafts. RA diameter was stratified as ≤5 or >5 mm and branch stent length as <60 or ≥60 mm. The primary end point was the cumulative incidence of RA branch occlusion per patient. Secondary end points were RA branch primary patency, cumulative incidence of RA target vessel instability (RA-TVI; defined as any occlusion, stenosis requiring reintervention, or type Ic/IIIc endoleak), and cumulative incidence of acute kidney injury (AKI) and/or new-onset dialysis, as defined by Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease (RIFLE) criteria. A total of 154 patients (62% male, 71.7 ± 9.8 years old) underwent BEVAR with 250 RA directional branches. The diameter was ≤5 mm in 76 RA branches (30%) and >5 mm in 174 RA branches (70%), whereas RA branch stent length was <60 mm in 94 branches (38%) and ≥60 mm in 156 branches (62%). After a median follow-up of 52 months (75% interquartile range, 29-85 months), there were four (2.6%) patients with four RA branch occlusions. The cumulative incidence of RA branch occlusion per patient was 2 ± 1.2% and 2.8 ± 1.4% at 1 and 5 years, respectively. The incidence of RA branch occlusion was significantly higher in smaller RAs (≤5 mm: 9 ± 5% vs >5 mm: 1 ± 1%; P = .021) and longer RA branches (<60 mm: 2 ± 2.2% vs ≥60 mm: 3 ± 1.3%; P = .797) at 5 years. Similarly, RA primary patency was lower in smaller RAs (≤5 mm: 93 ± 3% vs >5 mm: 95 ± 3%; P = .093) and longer RA branches (<60 mm: 98 ± 1% vs ≥60 mm: 89 ± 5%; P = .097) during the same period. Most RA-TVI events (80%) occurred in the first year. At 5 years, the cumulative incidence of RA-TVI was similar by RA diameter (≤5 mm: 10 ± 3% vs 11 ± 3; P = .666) and RA branch stent length (<60 mm: 13 ± 5% vs ≥60 mm: 8 ± 3%; P = .574). AKI occurred in eight patients (5%), with only two patients (1%) requiring new-onset dialysis. There was no significant difference in the cumulative incidence of AKI or new-onset dialysis by RA diameter (<5 mm: 13.3 ± 8.7% vs ≥5 mm: 3.0 ± 2.1%; P = .06), but patients with longer RA branches had an increased risk at 5 years (<60 mm: 5.7 ± 1.1% vs ≥60 mm: 7.7 ± 0.8%; P = .042). The incidence of RA branch occlusion was low (2.6%) among patients treated with BEVAR using Viabahn self-expandable and/or balloon-expandable stent grafts, but the risk was higher among patients with smaller RAs and longer RA branches. Similarly, smaller RAs and longer RA branches had lower primary patency, with an increased cumulative incidence of RA-TVI for longer branches. Patients with longer RA branches had an increased incidence of AKI or new-onset dialysis at 5 years. These data provide a benchmark for comparison of custom BEVAR and T-branch devices with other multibranched thoracoabdominal aortic aneurysm stent graft designs.