The impact of aortic distensibility in patients with bicuspid aortic valve stenosis

Abstract Introduction Ventricular adaptation to aortic stenosis (AS) is not only influenced by valve obstruction, but also by overall vascular load. Bicuspid aortic valve (BAV), present in a significant proportion of AS patients, may be associated with intrinsic aortopathy, with impact on aortic stiffness. We aimed to compare aortic stiffness, using aortic distensibility (AD) as surrogate marker, between AS patients with BAV and tricuspid aortic valve (TAV) and to assess its impact on LV remodeling. Methods Single-centre, prospective study of 158 patients with severe symptomatic AS (mean age 71±8 years, 50% male; mean transaortic gradient 61±17mmHg, mean indexed aortic valve area 0.4±0.1cm2/m2) referred for SAVR between 2019 and 2022. Patients with previous cardiomyopathy, concomitant moderate or severe aortic regurgitation and severe valve dysfunction beyond AS were excluded. Participants underwent serial transthoracic echocardiography (TTE) and cardiac magnetic resonance (CMR) within 3 months before SAVR. Valve morphology was determined either from TTE or surgical operative reports. Average systolic and diastolic ascending aortic dimensions were measured at cine images on the three-chamber and coronal left ventricular outflow views, at the level of pulmonary artery bifurcation. Maximum and minimum aortic areas were inferred and AD calculated. Relative aortic valve load (VL) and valvulo-arterial impedance (Zva) were calculated and correlated with AD. LV ventricular geometric remodeling was assessed in CMR. Results A total of 123 patients were included (71 years IQR 9; 50% male), 13% with BAV, and 87% with TAV (25 patients with undetermined valve morphology). All patients with high gradient, preserved LV ejection fraction. All BAV cases exhibited the ascending phenotype, without root involvement. BAV patients were younger, predominantly male, with lower prevalence of hypertension. Aortopathy was more prevalent in BAV patients. AS severity indexes were similar between groups, except for higher mean transvalvular gradients in BAV (Table 1). BAV patients exhibited higher AD (1.8 IQR2.3×10−3 vs 1.5 IQR1.5×10−3 mmHg−1, p=0.296-Figure 1) and VL (14 IQR10 vs 13 IQR5 mL/m², p=0.115-), though these differences were not statistically significant. Zva values were comparable between BAV and TAV groups (4.29 IQR 1.43 vs. 4.34 IQR 2.7 mmHg/mL/m², p=0.814). However, a negative correlation was found between AD and Zva in BAV patients (ρ=-0.615, p=0.011) but not in the TAV group (ρ= -0.151, p=0.122) (Figure 2). LV geometric remodeling had no significant correlation with AD in both group of patients (ρ -0.114, p=0.246 in BAV and ρ 0.137, p=0.264 in TAV). Conclusion AD was similar between BAV and TAV patients and showed no association with LV remodeling in either group. However, in BAV patients there was a significant negative correlation between AD and Zva, favouring a distinct ventricular-valvular and vascular relationship in this subgroup.