486 A Novel Cardiac Ct-Based Left Ventricular Outflow Tract Diameter Measurement Improves Concordance Between Aortic Valve Area And Gradient In Severe Low-gradient Aortic Stenosis Compared To Echocardiography

Abstract

Introduction: Accurate diagnosis of severe aortic stenosis (AS) as defined by an aortic valve area (AVA) <1.0 cm2, maximal aortic valve velocity (AVmax) ≥ 4.0 m/sec, and/or mean aortic valve gradient (AVG) ≥ 40 mm Hg is critical for timely aortic valve (AV) replacement. However, in 30% cases of severe AS by the AVA criteria, the mean AVG and AVmax are lower (non-severe AS range) leading to diagnostic difficulties in these patients with severe low-gradient AS (LG-AS). This discordance may be partly explained by erroneous measurement of the left ventricular outflow tract (LVOT) diameter at the aortic annulus by transthoracic echocardiography (TTE), an integral component of AVA calculation using the echo-based continuity equation (CE).