Background: The 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 is little data regarding the optimal location for Aa measurement and the agreement of ELCo with direct anatomical AVA measurement.
The aim of this study was to determine the optimal site of aortic area (Aa) measurement for calculation of the energy loss coefficient (ELCo), using ECG-gated computed tomography angiography (CCTA) planimetry AVA as a reference standard.
Methods: We analyzed 69 patients with AS who underwent both CCTA and TTE within 2 months. ELCo and CCTA planimetry AVA were compared using multiple sites for CCTA Aa measurement (sinus, sinotubular junction or ascending aorta).
Results: TTE AVA was 0.81±0.31 cm2, significantly smaller than CCTA AVA (0.96±0.46 cm2, p<0001). ELCo was 0.95±0.43 cm2 using sinotubular junction Aa, 0.92±0.41 cm2 using sinus Aa, and 0.91±0.4 cm2 using the ascending aorta (p=0.84, p=0.13, and p=0.08 compared to CCTA AVA). There was good agreement between CCTA AVA and ELCo using all Aa locations (Linn`s concordant correlation coefficient 0.89-0.90). On subgroup analysis of 16 patients most likely to be affected by pressure recovery (aortic diameter< 3cm and AVA≥1cm2) ELCo using the sinotubular junction Aa showed the best agreement with CCTA AVA as compared to the other Aa locations (Linn`s 0.84 vs. 0.75-0.77).
Conclusions: ELCo using Aa measurement at the sinotubular junction showed the best agreement with CCTA AVA.
