Aortic valve tissue characteristics and aortic stenosis in patients with bicuspid aortic valve

Introduction Bicuspid aortic valve (BAV) is frequently associated with valve dysfunction. When echocardiographic measurements for valvular disfunction assessment are discordant, computed tomography (CT) aortic valve calcium scoring can be useful. However, calcium scoring ignores the contribution of valvular fibrosis, which might precede calcification. Purpose To describe aortic valve (AV) tissue characteristics based on CT angiography in patients with BAV and their relationship with AV stenosis and its progression. Methods This is a secondary analysis of patients with BAV enrolled in a randomized clinical trial where echocardiography and ECG-gated contrast-enhanced computed tomography (CT) were acquired at baseline and after 3 years of follow-up [1]. Fibrotic and calcific AV volumes and their sum (fibrocalcific volume) were calculated using a standardized semiautomatic software (Autoplaque, Cedars-Sinai Medical Center) that provides a volumetric measure of tissues characteristics by exploiting their different pixel intensities [2]. AV tissue volumes were indexed to the annulus area. Results The cohort included 192 patients from 10 centers: they were mostly middle-aged (median age 46 years) men (80%) with relatively limited prevalence of baseline AV stenosis (mild 17.7%, moderate 4.7%). Most patients had a 3-sinus BAV (87%) and RL fusion phenotype (71%), while 24 (13%) presented a 2-sinus BAV. Compared to men, women showed a much stronger associations between age and fibrotic (R=0.548 vs R=0.152) as well as fibrocalcific (R=0.572 vs R=0.280) volumes. Compared with 3-sinus BAV, 2-sinus BAV presented higher calcific volume (p=0.026). Within 3 sinus BAV, RN BAV showed higher values of fibrotic (p=0.016) and fibrocalcific (p=0.032) volumes than RL BAV. In cross-sectional analysis, AV mean pressure gradient (MPG) was positively related with age and was larger in women and in patients with 2- compared with 3-sinus BAV. In separate multivariable linear regression analyses corrected for age, sex, BSA, hypercholesteremia, annulus area and 2- or 3-sinus BAV, fibrotic, calcific and fibrocalcific volume and Agatston Calcium score were positively related to MPG. In longitudinal analysis, the progression of MPG was faster in women than in men (0.33 [0 – 1.01] vs 0.25 [0 – 0.63] mmHg/year, p=0.035) and in patients with 2- than 3-sinus BAV (0.57 [0 – 0.98] vs. 0.25 [0 – 0.65] mmHg/year, p=0.035). On multivariable linear regression analyses corrected for age and sex, baseline calcific volume was positively associated with MPG growth (p<0.001). Conclusions Patients with a 2-sinus BAV present a higher burden of AV calcification and faster AV stenosis progression. Women with BAV presented a larger burden of fibrotic tissues and faster AV stenosis progression. Both calcific and fibrocalcific AV volumes are related to AV stenosis severity.