Aortic Stiffness in Heritable Aortopathies: Relationship to Aneurysm Growth Rate
Objective: This study compared aortic biomechanics in different heritable aortopathy syndromes and examined the clinical utility of aortic stiffness measurements. Methods and results: In 218 patients (55 Marfan, 47 bicuspid aortic valve (BAV), 47 isolated familial thoracic aneurysm (FTAD) and 69 matched controls) aortic biomechanics were measured by echocardiography with simultaneous blood pressure measurements. Patients were stratified by age as ≤40 years or >40 years. Aortic stiffness increased with age and aortic biomechanics were abnormal in all aortopathies, particularly in BAV and FTAD. Increased stiffness and pulse wave velocity were seen in BAV and FTAD in both age cohorts (p < 0.001) and both were stiffer than Marfan patients (p < 0.01). Marfan patients aged ≤40 years had stiffer aortas than controls, but those >40 years were similar to controls. Multivariate regression identified age as the dominant correlate with increased stiffness, and also aortic diameter and mean blood pressure (R2= 0.64; p < 0.001). Aortopathy patients with stiffness index > 16 had lower rate of increase in aortic diameter (0.25 ± 0.30 mm/year) than those with normal stiffness (0.68 ± 0.39 mm/year, p < 0.001). Whilst positive predictive value of increased stiffness for detection of aortopathy was high (93% in age ≤ 40 years, 87%, in age > 40 years), negative predictive accuracy was low (55% and 34% respectively). Conclusion: Abnormal biomechanics are common to all aortopathies, with greater abnormality in BAV and FTAD than in Marfan. Increased aortic stiffness is associated with slower rate of aneurysm progression.