Revascularization of occluded renal artery stent grafts after complex endovascular aortic repair and its impact on renal function

Background: Acute occlusion of renal bridging stent grafts after fenestrated/branched endovascular aortic repair (F/B-EVAR) is an acknowledged complication with high morbidity that often results in chronic dialysis dependence. The feasibility and effect of timely or late (≥6 hours of ischemia) renal artery revascularization has not been adequately reported. Methods: We performed a retrospective, multicenter study across 11 tertiary institutions of all consecutive patients who had undergone revascularization of renal artery stent graft occlusions after complex EVAR. The end points were technical success, association between ischemia time and renal function salvage, interventional complications, mortality, and mid-term outcomes. Results: From 2009 to 2019, 38 patients with 46 target vessels (TVs; eight bilateral occlusions) were treated for renal artery occlusions after complex EVAR (mean age, 63.5 ± 10 years; 63.2% male). Six patients had a solitary kidney (15.8%). Of the 38 patients, 16 (42.1%) had undergone FEVAR and 22 (57.9%) had undergone BEVAR. The technical success rate was 95.7% (44 of 46 TVs). The recanalization technique used was sole aspiration thrombectomy in 5.3%, aspiration thrombectomy and stent graft relining in 52.6%, and sole stent graft relining in 36.8%. The median renal ischemia time was 27.5 hours (range, 4-720 hours; interquartile range, 4-36 hours). Most patients (94.4%) had been treated after ≥6 hours of renal ischemia time, and 55.6% had been treated after 24 hours. In 14 patients (36.8%), renal function had improved after intervention (mean glomerular filtration rate improvement, 14.2 ± 9 mL/min/1.73 m²). However, 24 patients (63.2%) showed no improvement. Improvement of renal function did not correlate with the length of renal ischemia time. Of the 14 patients with bilateral renal artery occlusion or a solitary kidney, 9 experienced partial recovery of renal function and no longer required hemodialysis. In-hospital mortality was 2.6%. The cause of renal stent graft occlusion could not be identified in 50% of the TVs (23 of 46). However, in 19 (41.3%), significant stenosis or a kink of the renal stent graft was found. The median follow-up was 11 months (interquartile range, 0-28 months). The estimated 1-year patient survival and patency rate of the renal stent grafts was 97.4% and 83.8%, respectively. Conclusions: Revascularization of occluded renal bridging stent grafts after F/B-EVAR is a safe and feasible technique and can lead to significant improvement of renal function, even after long ischemia times (>24 hours) of the renal parenchyma or bilateral occlusion, as long as residual perfusion of the renal parenchyma has been preserved. Also, the long-term patency rates justify aggressive management of renal artery occlusion after F/B-EVAR.