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A widely used definition of low-flow low-gradient AS includes the following conditions: 

- Effective orifice area <1.0 cm2,

- LV ejection fraction <40%,
- Mean pressure gradient <30–40 mmHg.
A patient with a low ejection fraction but a resting AS velocity >4.0 m/s or mean gradient >40 mmHg does not have a poor left ventricle (LV). The ventricle is demonstrating a normal response to high afterload (severe AS), and ventricular function will improve after relief of stenosis. This patient does not need a stress echocardiogram.