Gisela Teixidó‐Turà

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BACKGROUND: In patients with bicuspid valve (BAV), ascending aorta (AAo) dilatation may be caused by altered flow patterns and wall shear stress (WSS). These differences may explain different aortic dilatation morphotypes. Using 4D-flow cardiovascular magnetic resonance (CMR), we aimed to analyze differences in flow patterns and regional axial and circumferential WSS maps between BAV phenotypes and their correlation with ascending aorta dilatation morphotype. METHODS: One hundred and one BAV patients (aortic diameter ≤ 45 mm, no severe valvular disease) and 20 healthy subjects were studied by 4D-flow CMR. Peak velocity, flow jet angle, flow displacement, in-plane rotational flow (IRF) and systolic flow reversal ratio (SFRR) were assessed at different levels of the AAo. Peak-systolic axial and circumferential regional WSS maps were also estimated. Unadjusted and multivariable adjusted linear regression analyses were used to identify independent correlates of aortic root or ascending dilatation. Age, sex, valve morphotype, body surface area, flow derived variables and WSS components were included in the multivariable models. RESULTS: The AAo was non-dilated in 24 BAV patients and dilated in 77 (root morphotype in 11 and ascending in 66). BAV phenotype was right-left (RL-) in 78 patients and right-non-coronary (RN-) in 23. Both BAV phenotypes presented different outflow jet direction and velocity profiles that matched the location of maximum systolic axial WSS. RL-BAV velocity profiles and maximum axial WSS were homogeneously distributed right-anteriorly, however, RN-BAV showed higher variable profiles with a main proximal-posterior distribution shifting anteriorly at mid-distal AAo. Compared to controls, BAV patients presented similar WSS magnitude at proximal, mid and distal AAo (p = 0.764, 0.516 and 0.053, respectively) but lower axial and higher circumferential WSS components (p < 0.001 for both, at all aortic levels). Among BAV patients, RN-BAV presented higher IRF at all levels (p = 0.024 proximal, 0.046 mid and 0.002 distal AAo) and higher circumferential WSS at mid and distal AAo (p = 0.038 and 0.046, respectively) than RL-BAV. However, axial WSS was higher in RL-BAV compared to RN-BAV at proximal and mid AAo (p = 0.046, 0.019, respectively). Displacement and axial WSS were independently associated with the root-morphotype, and circumferential WSS and SFRR with the ascending-morphotype. CONCLUSIONS: Different BAV-phenotypes present different flow patterns with an anterior distribution in RL-BAV, whereas, RN-BAV patients present a predominant posterior outflow jet at the sinotubular junction that shifts to anterior or right anterior in mid and distal AAo. Thus, RL-BAV patients present a higher axial WSS at the aortic root while RN-BAV present a higher circumferential WSS in mid and distal AAo. These results may explain different AAo dilatation morphotypes in the BAV population.

AIMS: To determine the efficacy of losartan vs. atenolol in aortic dilation progression in Marfan syndrome (MFS) patients. METHODS AND RESULTS: A phase IIIb, randomized, parallel, double-blind study was conducted in 140 MFS patients, age range: 5-60 years, with maximum aortic diameter <45 mm who received losartan (n = 70) or atenolol (n = 70). Doses were raised to a maximum of 1.4 mg/kg/day or 100 mg/day. The primary end-point was the change in aortic root and ascending aorta maximum diameter indexed by body surface area on magnetic resonance imaging after 36 months of treatment. No serious drug-related adverse effects were observed. Five patients presented aortic events during a follow-up (one in the losartan and four in the atenolol groups, P = 0.366). After 3 years of follow-up, aortic root diameter increased significantly in both groups: 1.1 mm (95% CI 0.6-1.6) in the losartan and 1.4 mm (95% CI 0.9-1.9) in the atenolol group, with aortic dilatation progression being similar in both groups: absolute difference between losartan and atenolol -0.3 mm (95% CI -1.1 to 0.4, P = 0.382) and indexed by BSA -0.5 mm/m2 (95% CI -1.2 to 0.1, P = 0.092). Similarly, no significant differences were found in indexed ascending aorta diameter changes between the losartan and atenolol groups: -0.3 mm/m2 (95% CI -0.8 to 0.3, P = 0.326). CONCLUSION: Among patients with MFS, the use of losartan compared with atenolol did not result in significant differences in the progression of aortic root and ascending aorta diameters over 3 years of follow-up.

PURPOSE: To determine the normal size and wall thickness of the ascending thoracic aorta (AA) and its relationship with cardiovascular risk factors in a large population-based study. MATERIALS AND METHODS: The mean AA luminal diameter was measured in 3573 Multi-Ethnic Study of Atherosclerosis (MESA) participants (age: 45-84 years), using gradient echo phase contrast cine MRI. Multiple linear regression models were used to evaluate the associations between risk factors and AA diameter. The median and upper normal limit (95th percentile) was defined in a "healthy" subgroup as well as AA wall thickness. RESULTS: The upper limits of body surface area indexed AA luminal diameter for age categories of 45-54, 55-64, 65-74, and 75-84 years are 21, 22, 22, and 28 mm/m(2) in women and 20, 21, 22, 23 mm/m(2) in men, respectively. The mean AA wall thickness was 2.8 mm. Age, gender, and body surface area were major determinants of AA luminal diameter (∼+1 mm/10 years; ∼+1.9 mm in men than women; ∼+1 mm/ 0.23 m(2) ; P < 0.001). The AA diameter in hypertensive subjects was +0.9 mm larger than in normotensives (P < 0.001). CONCLUSION: AA diameter increases gradually with aging for both genders among all race/ethnicities. The normal value of AA diameter is provided.