The Correlation Between Abdominal Aortic Aneurysm Sac Size And Hostile Proximal Neck Anatomy And Its Application In EVAR

Objective: To analysis the correlation between abdominal aortic aneurysm(AAA)diameter and hostile proximal neck anatomy(HPNA),to discuss the effect of HPNA on endovascular aneurysm repair(EVAR),then,to provide a reference for the clinical choice of the appropriate standard of aneurysm size at the time of decision making of EVAR.Methods: Infrarenal AAA patients who had undergone EVAR in the first affiliated hospital of Fujian medical university from January 2013 to February 2018 had been collected.Patients’ characteristics,comorbidities,aneurysm size and proximal neck morphology were analyzed.Preoperative computed tomography angiography(CTA)is used for disease diagnosis,and for measuring the maximum aneurysm diameters(MAD)and proximal neck anatomy characteristics including neck diameter,neck length,neck angulation,circumferential thrombus and calcification.According to AAA sac diameter,two groups were identified: small aneurysm group(<55mm)and large aneurysm group(≥55mm).The definition of HPNA was based on: neck length <15mm,neck diameter≥28mm,neck angulation>60°,circumferential thrombus>50%,calcification>50% and inverted cone.The aortic neck scoring system(ANSS)according to the Society for Vascular Surgery grading classification for morphologic risk was calculated.Independent samples t-test or Mann Whitney test is used for the comparison of measurement data,while chi-square test or Mann Whitney test is used for the comparison of enumeration data.Logistic regression analysis is used for analyzing the correlation between aneurysm diameter and HPNA.Results: A total of 134 EVAR patients(91%males,9%females)with a mean age of 70.4±8.5 years(range,48-88 years),and a mean aneurysm diameter of 57.3±12.0mm(range,39.5-107.1mm)were included.No differences were observed in demographics and comorbidities between the two groups(small aneurysm group: 74,55.2% vs.large aneurysm group: 60,44.8%).HPNA was present in 59/134(44.0%)patients and more likely to be present in large aneurysm group(P<0.001).In large aneurysm group the aortic neck score was higher(P<0.001),the likelihood for having HPNA increased for neck diameter by 3.5-fold(OR=3.500,P=0.043,95%CI: 1.038-11.796),angle by 5.2-fold(OR=5.236,P<0.001,95%CI: 2.264-12.110).No association existed for neck length(P=0.962),neck circumferential thrombus(P=0.456)and neck calcification(P=0.916).Conclusions: 1.HPNA is more likely in AAA with diameter≥55mm,mainly characterized by neck angulation>60°(the most common)and neck diameter≥28mm.2.Early EVAR for those who had SAAA with aneurysm diameter ranging from 40 to 55 mm should be recommended.