Grading abdominal aortic aneurysm rupture risk

BACKGROU ND: The aim of this paper was to develop a scoring system to grade the risk of rupture of an abdominal aortic aneurysm (AAA ) in individual patients. METHODS: Computed tomography angiography of an AAA were coupled with computational fluid dynamics (CFD) evaluation performed using open source software (ElmerSolver, Institute of Technology, Espoo, Finland). CFD criteria studied were: Oscillatory Shear Index (OSI ), time averaged wall shear stress (TAWSS ) and residence relative time (RR T) on both two-dimensional (2D) and three-dimensional (3D) models. AAA rupture predictors were analyzed and a scoring system was generated using Arabic numerals for all significant variables in order to grade the individual patient risk of rupture. RESUL TS: There were 143 patients examined. Ninety-one AAA s (18 ruptured AAA s), and 52 had a non-aneurysmal aorta. The 2D OSI was the best CFD criterion following multivariate analysis and RO C curves evaluation. An AAA was deemed respectively at low, moderate, or high risk of rupture, according to whether the risk score was defined as AAA I (total score <2.3), AAA II (2.3-6.5) or AAA III (>6.5). The only protective factor was found in diabetes (OR =0.775; CI: 0.665-0.902). CONCLUSIO NS: The Florence Risk Score for AAA rupture based on this report may be a useful tool to predict AAA rupture. A prospective multicenter registry will need to confirm its validity.