Effect of stent graft fixation types on pararenal aortic diameter and renal function after endovascular aortic repair

Background: This study aims to identify pararenal aortic diameter changes following endovascular aortic repair and to investigate the effects of suprarenal fixation on renal function. Methods: Between May 2006 and January 2019, a total of 168 patients (135 males, 33 females; mean age: 75.2±8.4 years; range, 48 to 93 years) who underwent endovascular aortic repair were retrospectively analyzed. To compare the effects of graft types, we measured the change in pararenal aortic diameter at four levels: below the celiac artery, below the superior mesenteric artery, at the lowest renal artery, and 1 cm below the lowest renal artery. To evaluate the effect of suprarenal fixation on renal function, serial measurements of serum creatinine, glomerular filtration rate, creatinine clearance rate, and estimated glomerular filtration rate were made. We examined the factors related to post-procedural aortic diameter. Results: The mean change in the aortic diameter was statistically significant, being 12.9±10% in the suprarenal fixation group and 6.19±6.9% in the infrarenal fixation group only at the lowest renal artery level (p=0.001). There was no significant difference in the rate of type I endoleak (p=0.330) or renal function and adverse events (p>0.107) between the groups. The formula for calculating post-procedural aortic diameter was as follows: post-procedural aortic diameter (renal artery level, mm) =1.845 (in case of suprarenal fixation) + 1.012 × pre-procedural aortic diameter (renal artery level, mm) + 0.029 × follow-up time (months) + 0.039 × oversizing (%) (R2=0.773, p<0.001). Conclusion: Suprarenal fixation affects the infrarenal aortic diameter at the lowest renal artery level without significant type I endoleak. However, it does not result in significant renal dysfunction. Pre-procedural aortic diameter, computed tomography follow-up time, suprarenal fixation type, and stent oversizing are the only definite independent correlation factors for postprocedural aortic diameter. This formula can predict the change of aortic diameter after endovascular aortic repair.