Age-dependent changes in elastic properties of thoracic aorta evaluated by magnetic resonance in normal subjects

Aortic stiffness is an independent cardiovascular risk factor. Cardiac magnetic resonance (CMR) allows evaluation of aortic elastic properties by different indexes such as distensibility, the maximum rate of systolic distension (MRSD) and pulse wave velocity (PWV). We sought to define age-dependent changes of indexes of elastic properties of the thoracic aorta in healthy subjects.

We enrolled 85 healthy subjects (53 males) free of overt cardiovascular disease subdivided into 6 classes of age (from 15 to >60 years). Distensibility, MRSD and PWV were measured by the analysis of CMR images acquired using a 1.5 T clinical scanner.

MRSD and distensibility decreased progressively through the classes of age (P < 0.001) after an initial plateau between 20 and 30 years in males and 15 and 20 years in females. Pulse wave velocity increased progressively with the age (P < 0.001). Distensibility was related to body mass index (P = 0.002), surface area (P < 0.005), weight (P = 0.005) and to left ventricular parameters such as mass index (P < 0.001) and end-diastolic volume index (P = 0.002). MRSD was related to end-diastolic volume index (P < 0.001) but not to body parameters. PWV was not related to body and ventricular parameters.

This study confirmed that physiological ageing is associated with a progressive impairment of the elastic properties of the aortic wall. Results of this study may be useful for the early identification of subjects with impaired aortic wall properties providing referral values of elasticity indexes assessed by CMR in different classes of age.