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).