Inconsistencies of echocardiographic criteria for the grading of aortic valve stenosis

Abstract

The present study tests the consistency of echocardiographic criteria for the grading of aortic valve stenosis. Current guidelines/recommendations define severe stenosis as an aortic valve area (AVA) <1 cm2 (or <0.6 cm2 adjusted for body surface area), mean pressure gradient (DeltaPm) >40 mmHg, or peak flow velocity (Vmax) >4 m/s. We tested the consistency of the three criteria for the grading of aortic valve stenosis in 3483 echocardiography studies performed in 2427 patients with normal left ventricular (LV) systolic function and a calculated AVA of < or =2 cm2. We calculated curve fits for the relationship between AVA and DeltaPm using the Gorlin equation and between AVA and Vmax based on the continuity equation for our study population. An AVA of 1.0 cm2 correlated to a DeltaPm of 21 mmHg and a Vmax of 3.3 m/s. Conversely, a DeltaPm of 40 mmHg corresponds to an AVA of 0.75 cm2 and a Vmax of 4.0 m/s to an AVA of 0.82 cm2. Consequently, severe stenosis was diagnosed in 69% of patients based on AVA, 45% on Vmax, and 40% on DeltaPm. Stroke volume was lower in inconsistently graded patients (65 +/- 11 mL vs. consistently graded: 70 +/- 14 mL, P < 0.001). The criteria for the grading of aortic stenosis are inconsistent in patients with normal systolic LV function. On the basis of AVA, a higher proportion of patients is classified as having severe aortic valve stenosis compared with mean pressure gradient and peak flow velocity. Discrepant grading in these patients may be partly due to reduced stroke volume.