The effect of aortic area measurement site on the energy loss coefficient: a comparison between echocardiography and cardiac computed tomography angiography in patients with aortic stenosis

AimThe energy loss coefficient (ELCo) has been suggested as a more accurate indicator of aortic stenosis (AS) severity as compared to transthoracic echocardiography (TTE) aortic valve area (AVA). There are little data regarding the optimal location for aortic area (Aa) measurement needed for ELCo calculation and the agreement of ELCo with direct anatomical AVA measurement. The aim of this study was to determine the optimal site of Aa measurement for calculation of the ELCo, using cardiac computed tomography angiography (CCTA) AVA planimetry as the reference standard. MethodsWe analyzed 69 patients with AS who underwent both CCTA and TTE. ELCo and CCTA planimetry AVA were compared using multiple sites for CCTA Aa measurement (sinus, sinotubular junction, or ascending aorta). ResultsCCTA AVA was 0.960.46cm(2). ELCo was 0.95 +/- 0.43cm(2) using sinotubular junction Aa, 0.92 +/- 0.41cm(2) using sinus Aa, and 0.91 +/- 0.4cm(2) using the ascending aorta (P=.84, P=.13, and P=.08 compared to CCTA AVA). There was good agreement between CCTA AVA and ELCo using all Aa locations (0.89-0.90). On subgroup analysis of 16 patients most likely to be affected by pressure recovery (aortic diameter<3cm and AVA 1cm(2)), ELCo using the sinotubular junction Aa showed the best agreement with CCTA AVA as compared to the other Aa locations (0.84 vs 0.75-0.77). ConclusionsELCo using Aa measurement at the sinotubular junction showed the best agreement with CCTA AVA. We therefore recommend using the sinotubular junction Aa for ELCo calculation.