Abstract 14350: CVSA Early Career Investigator Award Finalist: Association of Aneurysm Wall Stresses With Diameter Indices and Three-Year Outcomes in Veterans

Introduction: Current diameter-based guidelines for ascending thoracic aortic aneurysms do not consistently predict risk of dissection/rupture. Aneurysm wall stresses may better predict risk but correlate weakly with diameter. Our objective was to correlate aneurysm wall stresses with indexed diameters in relation to 3-year all-cause mortality. Methods: Finite element analyses were performed on 255 patients with aneurysms ≥4.0cm. Three-dimensional geometries were reconstructed from computed tomography and models developed accounting for pre-stress geometries. A fiber-embedded hyperelastic material model was applied to obtain circumferential (circ.) and longitudinal (long.) wall stress distributions under systolic pressure. Peak wall stresses were compared across diameter/[body surface area (BSA)] and diameter/[height (ht)] thresholds from the literature. Hazard ratios for 3-year all-cause mortality and surgical aneurysm repair were estimated using cause-specific Cox proportional hazards models. Results: Compared to the 22% cumulative incidence of aneurysm repair at 3 years, indexed diameter indicated repair at baseline in 17/255 (7%) patients, including only 4/230 (1.7%) with diameter <5.5cm. Peak wall stresses did not significantly differ across literature-proposed thresholds for diameter/BSA (circ: p=0.15; long: p=0.18), but did differ for diameter/ht (circ: p=0.003; long: p=0.048). All-cause mortality was associated with peak long. stresses independent of indexed diameter (p=0.009). Peak long. stresses were best predicted by diameter (c-statistic=0.66), followed by diameter/ht (c-statistic=0.59), and diameter/BSA (c-statistic=0.55). Conclusions: Diameter/ht better stratified peak wall stresses than diameter/BSA. Peak long. stresses independently predicted all-cause mortality, adjusting for age and indexed diameter. Peak long. stresses may aid risk stratification for adverse events.