Doppler echocardiography data
All Doppler echocardiography exams were performed with a Vivid S5 (GE® Vingmed Ultrasound, Israel) and a Vivid T8 (GE® Medical Systems, China) ultrasound system. Echocardiographic data was collected and analysed according to the American Society of Echocardiography and European Association for Cardiovascular Imaging guidelines by 5 experienced certified cardiologists (cardiac imaging specialists, Level III). Anonymous electronic recordings were analysed according to current echocardiographic recommendations. 12–14
Aortic valve phenotype was assessed in the parasternal short-axis view. BAV was classified according to Schaefer et al as: I, fusion of coronary leaflets, II, fusion of right coronary and non-coronary leaflets and III: fusion of non-coronary and left coronary leaflets.15
Left ventricular outflow tract (LVOT) diameter was measured at the insertion of the leaflets in a zoom of the parasternal long-axis view and used to calculate the LVOT area. Stroke volume was obtained by multiplying the LVOT area by the velocity time integral measured by pulsed wave Doppler in the LVOT. Stroke volumen was indexed to BSA to obtain stroke volume index. The transvalvular flow rate was calculated by dividing the stroke volume by the left ventricular ejection time. LVEF was calculated with Simpson’s biplane method.
AS haemodynamic severity was assessed with the following parameters: dimensionless index (ratio of the VTI of the LVOT flow on the VTI of the aortic valve flow), mean gradient (modified Bernoulli equation), maximum Doppler velocity (Vmax, with continuous wave Doppler) and aortic valve area (AVA, calculated with continuity equation). AS severity was categorised based on fulfilment of at least 2 criteria. into mild AS (AVA >1.5cm2, Vmax <3.0m/s, mean gradient <20mmHg), moderate AS (AVA 1-1.5cm2, Vmax 3.0-3.9m/s, mean gradient 20-39mmHg) and severe AS (AVA <1cm2, Vmax ≥4.0m/s, mean gradient ≥40mmHg, dimensionless index ≤ 0,25).14
All patients underwent baseline TTE and follow-up imaging studies according medical advise. Outcomes including aortic valve replacement (AVR), transcatheter aortic valve replacement (TAVR) all-cause mortality and cardiovascular mortality were collected until 20 March 2020.
AVR was defined as the need for mechanical (surgical or transcatheter replacement) treatment due to severe symptomatic AVS according current guidelines, including an estimated aortic valve area <0.9 cm2. The standard of practice at our institution is to intervene on severe AS primarily on the basis of cardiovascular symptoms or ventricular dysfunction, based on current recommendations. In asymptomatic patients, referral for surgery was made according to international guidelines: dilated aortic sinus or ascending aorta >50 mm in BAV or left ventricle ejection fraction <50%. 14
All procedures followed the principles of the Declaration of Helsinki and good clinical practice regulations.