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Low flow, low gradient severe aortic stenosis

William H Gaasch, MD
Section Editor
Catherine M Otto, MD
Deputy Editor
Susan B Yeon, MD, JD, FACC


Symptomatic patients with severe aortic stenosis (AS) generally have a substantial improvement in symptoms and increased survival after aortic valve replacement. These beneficial results can even be observed in those who have developed left ventricular (LV) dysfunction and heart failure [1,2]. However, not all such patients benefit from aortic valve replacement. In particular, the subset of patients with AS and a low transvalvular pressure gradient due to significant LV failure have considerable operative risk and limited potential for improvement with surgery [3].

Issues relating to low gradient AS will be reviewed here. The clinical presentation and treatment of AS are discussed separately. (See "Clinical manifestations and diagnosis of aortic stenosis in adults" and "Medical management of asymptomatic aortic stenosis in adults" and "Indications for valve replacement in aortic stenosis in adults", section on 'Low gradient aortic stenosis'.)


The transaortic gradient depends upon the severity of the stenosis and upon flow rate, which is determined by the stroke volume and systolic ejection period. Most patients with symptomatic severe aortic stenosis (AS) have an aortic velocity of 4 m/s or higher, corresponding to a mean transvalvular pressure gradient of at least 40 mmHg and a valve area that is <1.0 cm2 (table 1B).

Low flow, low gradient severe AS (also referred to as low output, low gradient severe AS) is defined as a valve area ≤1.0 cm2 with an aortic velocity <4.0 m/s or mean transvalvular pressure gradient ≤40 mmHg [4]. Low flow, low gradient severe AS occurs in the setting of a low flow rate across the valve either due to left ventricular (LV) systolic dysfunction with reduced LV ejection fraction (LVEF) or to small ventricular volumes with LV hypertrophy and a normal LVEF. When LVEF is normal, low flow is defined as a stroke volume index ≤35 mL/m2. Among 971 patients in the PARTNER trial, the following findings were reported [5]:

Low flow (LV stroke volume index ≤35 mL/m2) in 530 patients (55 percent)


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Literature review current through: Sep 2016. | This topic last updated: Feb 6, 2014.
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