Abstract 15119: Diastolic Peak Wall Stresses in Marfan vs Non-Marfan Ascending Thoracic Aortic Aneurysm: A Propensity Score Analysis

Abstract

Introduction: Marfan syndrome (MFS) carries a risk of aortic dissection and death. The current aneurysm repair guideline of diameter ≥5cm may neglect up to 15% of MFS patients who dissect at smaller diameters. Since dissection can occur biomechanically when wall stress exceeds tissue strength, patient-specific biomechanics may enhance risk stratification for MFS patients. The goal of this study was to compare aneurysm wall stresses between propensity score-matched MFS and non-MFS aneurysm patients. Methods: The cohort consisted of 5 MFS and 42 non-MFS patients with aortic aneurysm. Preoperative CTA or MR scans were used to create 3D hexahedral meshes. Finite element analysis was performed with MFS and nonMFS material properties to determine peak (99th percentile) diastolic stresses[TE1] . Propensity scores were calculated by logistic regression using age, sex, height, hypertension, diabetes, smoking history, valve type, and sinus diameter. Five pairs were formed by 1:1 optimal matching without replacement. Comparisons used the paired t-test. Results: Diameters were similar at the sinus but lower for MFS at the STJ (3.4±0.5 vs 3.9±0.7cm, p=0.003) and the ascending aorta (3.1±0.5 vs 4.3±0.5cm, p<0.001). Peak circumferential stresses (CS) were similar between MFS and nonMFS aneurysms across all regions. As well, peak longitudinal stresses (LS) were similar between the two cohorts across all regions (Fig 1). Conclusion: Both CS and LS were similar at all regions for MFS vs non-MFS patients. Because LS has been implicated in acute dissection and LS were similar, differences in tissue strength, rather than wall stress, are most likely causes of high dissection rates in MFS due to material weakness from fibrillin mutation.