Prognostic value of energy loss coefficient for predicting asymptomatic aortic stenosis outcomes: direct comparison with aortic valve area

Background: The pressure recovery-adjusted aortic valve area (AVA), called the energy loss coefficient (ELCo), is theoretically a more accurate parameter for evaluating aortic stenosis (AS) severity. The aim of this study was to compare the prognostic value of ELCo with that of conventional AVA.

Methods: Indexed AVA (iAVA) was measured using Doppler echocardiography in 301 asymptomatic Japanese patients with AS and preserved left ventricular ejection fractions. Sinotubular junction diameter was also measured, and the indexed ELCo (iELCo) was calculated. Patients were followed for major cardiac events, including cardiac death, ventricular fibrillation, myocardial infarction, heart failure requiring admission, and aortic valve replacement.

Results: The mean sinotubular junction diameter was 2.5 ± 0.3 cm, and >90% of patients had sinotubular junction diameters < 3 cm. There was a quadratic correlation between iAVA and iELCo (r = 0.97, P < .001). During a median of 17.4 months of follow-up, 90 patients had major cardiac events. Statistical analysis failed to show any superiority of iELCo over iAVA for predicting major cardiac events. However, iELCo stratified high-risk patients for cardiac outcome in a subset of patients whose AS grades were classified as severe using iAVA and in those whose AS severity was inconsistent (iAVA < 0.6 cm²/m² but mean pressure gradient < 40 mm Hg).

Conclusions: The calculation of iELCo may not be always required, even in patients with asymptomatic AS with small aortic roots. However, this index should be calculated in patients whose AS grading assessed by iAVA is severe and in those in whom AS severity criteria are inconsistent.