Background:
Downstream pressure recovery (PR) in the aorta affects transvalvular pressure gradient measurement and calculation of aortic valve area by continuity equation in patients with aortic stenosis (AS).
Methods:
To assess the clinical importance of PR on evaluation of severity of AS, echocardiographic data in 1562 patients with asymptomatic aortic stenosis (mean age 67 ± 10, 39% women, 51% hypertensive) recruited in the Simvastatin Ezitimibe in Aortic Stenosis (SEAS) study was used. The inner diameter of the ascending aorta was measured at annulus and at sinutubular junction. The aortic valve area (AVAI) was calculated from annular diameter and velocity time integrals from sub- and transaortic flow by Doppler. PR and PR corrected AVAI assessed as energy loss index (ELI) were calculated by previously published equations. Severe aortic stenosis was defined as AVAI <0.60cm
2
/m
2
and ELI <0.55cm
2
/m
2
, respectively. Patients were grouped into tertiles of peak transaortic Doppler velocity (<2.79, 2.79 –3.32, ≥3.33 m/sec, respectively).
Results:
In the total study population, PR ranged from 1.22–16.75 mmHg (mean 5.9±2.3), AVAI from 0.20 –1.85 cm
2
/m
2
(mean 0.67±0.22) and ELI from 0.22–5.94 cm
2
/m
2
(mean 0.89±0.45). PR increased significantly with severity of AS (Table 1
). Both AVAI and ELI decreased with increasing peak transaortic velocity, and the overestimation of AS severity by using unadjusted AVA was largest in the lowest tertile (Table 1
).
Conclusion:
Severity of AS is often overestimated in milder degrees of asymptomatic AS if correction for pressure recovery is not performed. Adjustment of AVA for the effect of energy loss should be performed routinely, and this may be especially important for accuracy of severity assessment in patients with relatively low transvalvular velocities.
Table 1
Echocardiographic evaluation of severe aortic stenosis: impact of three-dimensional imaging and correction for pressure recovery
