Echocardiography
Echocardiographic data were drawn from complete echocardiograms including 2D, M-mode, and color doppler. Peak velocity was calculated by continuous wave doppler, mean gradient was calculated by averaging instantaneous pressure gradients converted from measured velocities using the Bernoulli equation, and aortic valve area (AVA) was calculated by the continuity equation. Biplane Simpson’s technique was used to estimate ejection fraction (EF). Aortic valve phenotype was assessed in the parasternal short-axis view. Severity of aortic stenosis was assessed using established criteria for mean gradient, peak velocity, and aortic valve area. Though the echocardiography reports used to identify patients were only obtained from exams occurring between 2013-2018, we reviewed the electronic medical record for the first and last available echocardiograms between the period of January 1, 2005 and November 1, 2020. These were used to calculate the yearly progression rate of mean gradient (mmHg/year) and peak velocity (m/s/year).