This study aimed to develop a transthoracic echocardiography-based formula to estimate left ventricular outflow tract area in severe aortic stenosis and to perform a preliminary validation. Computed tomography was used as the reference standard.

Retrospective cohort study including 66 patients divided into a development cohort (n=35) and a validation cohort (n=31). Least absolute shrinkage and selection operator (LASSO) regression was used to identify predictive variables.

Four variables were selected: left ventricular end-systolic volume, aortic annulus diameter, maximum outflow tract velocity, and height, which were used to develop a predictive model. In the validation cohort, the proposed formula demonstrated a high coefficient of determination (R2=0.757) and good accuracy, with a mean absolute percentage error of 8.3%, significantly lower than that of the conventional echocardiographic method (49.8%), which showed systematic underestimation (P <.0001). Bland-Altman analysis showed no significant systematic bias (bias=–7.44mm2). Furthermore, 96.8% of predictions were within a ± 20% error margin.

The proposed formula showed promising preliminary results as an alternative to the conventional method for estimating left ventricular outflow tract area using transthoracic echocardiography. Further validation in larger cohorts is required before clinical adoption.