Thoracic Aortic Aneurysm Growth in Bicuspid Aortic Valve Patients: Role of Aortic Stiffness and Pulsatile Hemodynamics

Background-Bicuspid aortic valve (BAV) is the most common congenital cardiac abnormality. A thoracic aortic aneurysm (TAA) is present in approximate to 50% of BAV patients, who also have an 8-fold higher risk of aortic dissection than the general population. Because the health of the aorta is directly reflected in its stiffness and pulsatile hemodynamics, we hypothesized that measures of aortic stiffness and arterial load would be associated with TAA growth in BAV. Methods and Results-Twenty-nine unoperated participants with TAA due to BAV who had serial imaging were recruited. Aortic stiffness and steady and pulsatile arterial load were evaluated with validated methods that integrate arterial tonometry with echocardiography. TAA growth was assessed retrospectively based on available imaging, blinded to hemodynamic status. Multivariable linear regression assessed associations of aortic stiffness and hemodynamic variables with TAA growth, adjusting for potential confounders. Overall, 66% of participants were men. Mean +/- SD for age, baseline aneurysm size, growth rate, and followup time were 57.2 +/- 8.3 years, 46.9 +/- 3.6 mm, 0.75 +/- 0.81 mm/y, and 2.9 +/- 3.3 years, respectively. We found that greater aortic stiffness (beta +/- SE for carotid-femoral pulse wave velocity: 0.30 +/- 0.13. P=0.03) and aortic characteristic impedance (beta +/- SE: 0.46 +/- 0.18, P=0.02), as well as lower total arterial and proximal aortic compliance (beta +/- SE: -0.44 +/- 0.21, P=0.05, and -0.63 +/- 0.16, P=0.001, respectively) were independently associated with faster aneurysm growth. Conclusions-In patients with TAA due to BAV, measures of greater aortic stiffness and pulsatile arterial load indicate an association with accelerated aneurysm expansion. Assessing arterial hemodynamics may be useful for risk stratification and disease monitoring in TM patients with BAV.