How is aortic stenosis (AS) staged in noncardiac surgery patients?

Updated: Jul 16, 2021
  • Author: Lindsay A (Finger) Raleigh, MD; Chief Editor: Sheela Pai Cole, MD  more...
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The severity of AS determines the appropriate course of therapy (ie, medical management or surgical intervention) for these patients. AS severity is staged on the basis of the following factors [8] :

  • Degree of stenosis/valve hemodynamics
  • LV ejection fraction (LVEF)
  • Absence or presence of symptoms

Stages are defined as follows (see Table 1 below):

  • Stage A - Patients at risk for AS
  • Stage B - Patients with progressive hemodynamic obstruction
  • Stage C - Patients with severe but asymptomatic disease
  • Stage D - Patients with severe symptomatic AS 

Table 1. Stages of Aortic Stenosis [8] (Open Table in a new window)

Stage Definition Symptoms LVEF  Valve Hemodynamics 

At risk

(eg, BAV, sclerosis)

- Normal

 Vmax  < 2 m/s


Progressive AS 

(mild to moderate)

- Normal


     Vmax 2.0-2.9 m/s

     Mean pressure gradient < 20 mm Hg


     Vmax 3.0-3.9 m/s

     Mean pressure gradient 20-39 mm Hg

C1 Asymptomatic severe AS - Normal

Vmax ≥4 m/s

Mean pressure gradient ≥ 40mm Hg

AVA ≤1.0 cm2


Asymptomatic severe AS

with low LVEF


Vmax ≥4 m/s

Mean pressure gradient ≥40 mm Hg

AVA ≤1.0 cm2


Symptomatic severe AS

+ Normal or ↓

Vmax ≥4 m/s

Mean pressure gradient ≥40 mm Hg

AVA ≤1.0 cm2


Symptomatic severe 

low-flow, low-gradient

AS with low LVEF


Vmax < 4 m/s

Mean pressure gradient < 40 mm Hg

AVA ≤1.0 cm2


Symptomatic severe 

low-flow, low-gradient AS

+ Normal

Vmax < 4 m/s

Mean pressure gradient < 40 mm Hg

AVA ≤1.0 cm2

AS = aortic stenosis; AVA = aortic valve area; BAV = bicuspid aortic valve; LVEF = left ventricular ejection fraction; Vmax = maximum aortic jet velocity.

Two subsets of severe AS (stages D2 and D3) are defined by low-flow and low-gradient valvular hemodynamics. In these subsets, AS is defined by an aortic valve area (AVA) of 1.0 cm2 or less but a maximum aortic jet velocity (Vmax) of less than 4.0 m/s and a mean pressure gradient of 40 mm Hg or lower. The low velocity and low gradient are a result of a low flow rate across the valve that is due to either (1) poor LV systolic function (reduced LVEF) secondary to the valvular pathology or (2) LV hypertrophy with small ventricular volumes and resultant small stroke volumes despite a normal LVEF.

Some patients with a primary cardiomyopathy may have a low valvular gradient as a result of the reduced forward flow, which results in limited valve opening and a misleadingly low calculated valve area. These patients are considered to have so-called pseudostenosis because their symptoms are due to poor LV systolic function rather than valvular pathology.

A dobutamine stress echocardiogram can differentiate between patients with pseudostenosis and those with true AS by augmenting cardiac output. Patients with true AS will have an increase in the mean pressure gradient but no increase in the AVA, whereas patients with pseudostenosis will have an increase in the AVA but no increase in the mean pressure gradient.

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