SEX DIFFERENCES IN THORACIC AORTIC ANEURYSM GROWTH: ROLE OF AORTIC STIFFNESS

Abstract

Thoracic Aortic Aneurysm (TAA) is a deadly disease, affecting adults of all ages. Presently, the only parameter available for risk prediction is TAA size. However, many individuals suffer an aortic dissection with aneurysms that are smaller than guideline-based cutoffs for repair. Further, women with thoracic aortic aneurysms (TAAs) have faster aneurysm growth and greater risk of acute aortic syndromes and death than men. Since the stiffness of the aorta reflects the health of its wall, we hypothesized that aortic stiffness would be independently associated with TAA growth, and that sex would significantly modify this association. One hundred and thirty unoperated TAA subjects were recruited. Maximal aneurysm size at the oldest and latest imaging studies was measured; aneurysm growth rate was calculated as mm/year. Aortic stiffness was assessed by carotid-femoral pulse wave velocity (cfPWV) using applanation tonometry. Unadjusted and multivariable linear regression analyses assessed the association of cfPWV with TAA growth. Models were adjusted for age, sex, body size, aneurysm etiology and location, baseline aneurys size, follow-up time, mean arterial pressure, history of hypertension, diabetes and smoking, and concordant/ discordant nature of the imaging modality. We also tested the interaction term sex*cfPWV in the prediction of TAA growth. Seventy four percent of subjects were men. Mean±SD age, baseline aneurysm size and follow-up time were 62.9±11.8 years, 45.3±4.0 mm and 3.3±3.0 years, respectively, and not different by sex. cfPWV was 9.8±4.3 m/s in women and 9.5±3.2 m/s in men (P=0.70). TAA growth rate was 1.0±1.0 mm/year in women and 0.4±0.6 mm/year in men (P=0.006). Unadjusted regression results are depicted in the Figure. In multivariable linear regression, cfPWV was independently associated with TAA growth (β±SE for 1 m/s increase in cfPWV: 0.06±0.02, P=0.02). Other independent predictors of faster aneurysm growth were female sex and longer follow-up time (P<0.05 for each), but not baseline aneurysm size (P=0.28). The sex*cfPWV interaction term was significant (P<0.0001), thus sex-specific models were performed. cfPWV was independently associated with faster aneurysm growth in women (β±SE: 0.21±0.09, P=0.03), but not in men (β±SE: -0.001±0.024, P=0.94). Among TAA patients, higher aortic stiffness is independently associated with faster aneurysm growth, and findings are specific to women. Our findings highlight poorer aortic wall health, reflected by greater aortic stiffness, as a potential mechanism for TAA expansion, especially in women. Aortic stiffness assessment may represent a future target for TAA-related risk stratification, monitoring and therapeutics aimed at containing TAA growth.