Estimated Left Ventricular Outflow Tract Diameter: Proposal of an Equation for Clinical Use in Adults from The ELSA Brasil Study data.

Left ventricular outflow tract diameter (LVOTd) is essential for estimating stroke volume and aortic stenosis severity, but technical limitations may affect its accuracy. A predicted LVOTd may overcome these issues, though it has not been validated in large populations. We studied the participants of the representative random sample and with ≥ 60 y-o from the Elsa-Brasil study with echocardiogram performed (n=3,267), divided into a derivation (70%) and a validation subgroup (30%). In the derivation cohort, independent determinants of LVOTd were identified, and a regression equation was derived. In the validation cohort, the performance of LVOTELSA was evaluated and compared with previously published formulas. In our derivation sample (n= 1,822; 58.9 ± 9.5 y-o; 52% females), the mean measured LVOTd was 19.5 ± 2.5 mm. The strongest predictors of LVOTd were sex, height, aortic root diameter (AoDiam), and LV end-diastolic diameter (LVEDD), deriving the equation LVOTELSA = 0.03 + [0.59 x male] + [0.04 x height] + [0.22 x AoDiam] + [0.13 x LVEDD]. In the validation sample (n=739), LVOTELSA showed a high correlation (r=0.63) with measured LVOTd with similar agreement to LVOTPestelli (r=0.61), but worse with LVOTBSA(r=0.47). These differences are reflected in relevant differences in stroke volumes. LVOTELSA showed good performance in a general adult population and may be used as an alternative when direct echocardiographic measurement of LVOTd is not feasible.