Aortic stiffness in aortic valve stenosis: reply

We appreciate the interest of Nemes and Forster in our article1 and we would like to warmly thank them. The main purpose of our study was to assess the relationship between aortic stiffness, left ventricular (LV) function, and BNP release in a series of patients with severe aortic stenosis (AS) and preserved LV ejection fraction. A normal control group would have been useful for the comparison of arterial mechanical properties, but matching on age and cardiovascular risk factors may remain challenging. Antonini-Canterin et al.2 showed in a previous study that carotid stiffness, assessed by e-tracking, is similar in patients with calcific AS and in control patients of similar age, sex, and cardiovascular risk factors. However, at the level of the ascending aorta the results may differ, and aortic stiffness in patients with AS could be higher than in matched control subjects, considering the possible damage to the endothelium due to turbulent flow transmitted from the stenotic aortic valve. This could also explain the improvement of aortic stiffness after aortic valve replacement in the study of Nemes et al.3 Whether this improvement in aortic stiffness could contribute to the reverse remodelling of LV after aortic valve replacement has to be demonstrated. In our study, aortic beta index was used to assess arterial mechanical properties. It is less affected by arterial pressure changes since it is a parameter adjusted for the logarithmic relationship between stiffness indices and pressure.4 Young's incremental elastic modulus, which takes into account the thickness of the arterial wall, estimates the elastic properties of the arterial wall material and could provide important additional information on the intrinsic arterial mechanical properties. Unfortunately, the current available transthoracic echocardiographic methods do not allow the assessment of this parameter at the level of the ascending aorta. To improve the assessment of aortic mechanical properties, future development of high sensitive e-tracking systems is needed.