Evaluating proximal clamp site and intraoperative ischemia time among open repair of juxtarenal aneurysms

Background: The proportion of open aneurysm repairs requiring at least a suprarenal clamp has increased in the past few decades, partly owing to preferred endovascular approaches for most patients with infrarenal aneurysms, suggesting that the management of aortic clamp placement has become even more relevant. This study evaluated the association between the proximal clamp site and intraoperative ischemia times with postoperative renal dysfunction and mortality. Methods: We used the Vascular Quality Initiative to identify all patients undergoing open repairs of elective or symptomatic juxtarenal AAAs from 2004 to 2018 and compared outcomes by clamp site: above one renal artery, above both renal arteries (suprarenal), or above the celiac trunk (supraceliac). Outcomes evaluated included acute kidney injury (AKI), new-onset renal failure requiring renal replacement therapy (RRT), 30-day mortality, and 1-year mortality. We used multilevel logistic regressions and Cox proportional hazards models, clustered at the hospital level, to adjust for confounding. Results: We identified 3976 patients (median age, 71 years; 70% male; 8.2% non-Caucasian), with a median aneurysm diameter of 5.9cm (interquartile range [IQR], 5.4-6.8 cm). Proximal clamp sites were above one renal artery (31%), suprarenal (52%), or supraceliac (17%). The rates of unadjusted outcomes were 20.5% for AKI, 4.1% for new-onset RRT, 4.9% for 30-day mortality, and 8.3% for 1-year mortality. On adjusted analyses, independent of ischemia time, suprarenal clamping relative to clamping above a single renal artery had higher odds of postoperative AKI (adjusted odds ratio [aOR], 1.50; 95% confidence interval; 95% CI, CI, 1.28-1.75), but similar odds for new-onset RRT (aOR, 1.27; 95% CI, 0.79-2.06) and 30-day mortality (aOR, 1.12; 95% CI, 0.79-1.58) and hazards for 1-year mortality (adjusted hazard ratio, 1.12; 95% CI, 0.861.45). However, every 10 minutes of prolonged intraoperative ischemia time was associated with an increase in odds or hazards ratio of postoperative AKI by 7% (IQR, 3%-11%), new-onset RRT by 11% (IQR, 4%-17%), 30-day mortality by 11% (IQR, 6%-17%), and 1-year mortality by 7% (IQR, 2%-13%). Patients with more than 40 minutes of ischemia time had notably higher rates of all four outcomes. Conclusions: Suprarenal clamping relative to clamping above a single renal artery was associated with AKI, but not new-onset RRT or 30-day mortality. However, the intraoperative renal ischemia time was independently associated with all four postoperative outcomes. Although further studies are warranted, our findings suggest that an expeditious proximal anastomosis creation is more important than trying to maintain clamp position below one renal artery, suggesting that suprarenal clamping may be the best strategy for open AAA repair when needed to efficiently perform the proximal anastomosis.