Clinical Implication of Energy Loss Coefficient in Patients With Severe Aortic Stenosis Diagnosed by Doppler Echocardiography

Abstract

Background The Doppler-derived energy loss coefficient (ELCo), which can take into account the pressure recovery phenomenon and reconcile discrepancies between the aortic valve effective orifice area (EOA) obtained by the Gorlin formula using a catheter (EOA_cath) and the EOA obtained by the Doppler continuity equation (EOA_Dop), is proposed as an equivalent index to represent EOA_cath. Therefore, the purpose of this study was to evaluate the clinical impact of ELCo in patients with severe aortic stenosis (AS). Methods and Results Thirty-three patients with severe AS were assessed by Doppler examination [EOA obtained by the continuity equation (EOA_Dop) ≤1.0 cm²], and referred to the cardiac catheterization laboratory for evaluation of EOA obtained by the Gorlin formula (EOA_cath). Patients with ELCo ≤1.0 cm² (n=26) had significantly lower incidence of symptoms related to AS compared with those having ELCo >1.0 cm² (n=7) (p=0.002). Superior concordance in severity of AS was demonstrated between EOA_cath and ELCo compared with EOA_cath and EOA_Dop (κ=0.52, and κ=0.32, respectively). Conclusions In 21% of patients with "severe" AS diagnosed by Doppler echocardiography, the ELCo value indicated moderate rather than severe AS. These patients had significantly lower incidence of symptoms compared with patients who had ELCo ≤1.0 cm². (Circ J 2008; 72: 1265 - 1269)