From the Guidelines
Aortic stenosis severity is classified into three grades based on aortic peak flow velocity: mild, moderate, and severe, with very severe being a subset of severe. The severity grades of aortic stenosis based on aortic peak flow velocity are as follows:
- Mild aortic stenosis is defined by a peak flow velocity of less than 3.0 m/s 1.
- Moderate aortic stenosis corresponds to a velocity of 3.0 to 4.0 m/s 1.
- Severe aortic stenosis is characterized by a velocity of greater than 4.0 m/s 1. Some studies suggest that very severe aortic stenosis can be diagnosed when the velocity exceeds 5.0 m/s or when there is a peak transvalvular velocity >5.5 m/s 1. These velocity measurements reflect the pressure gradient across the aortic valve, with higher velocities indicating greater obstruction to blood flow. The velocity measurements are typically obtained using continuous-wave Doppler echocardiography, which is the preferred method for assessing aortic stenosis severity 1. Other parameters used alongside peak velocity include mean pressure gradient, valve area, and velocity ratio, which together provide a comprehensive assessment of stenosis severity 1. The decision to intervene is based on the presence of symptoms, the severity of the stenosis, and the patient's overall clinical condition, with severe and very severe stenosis often requiring valve replacement, especially when symptoms are present 1.
From the Research
Aortic Peak Flow Velocity Severity Grades
The severity grades of aortic stenosis based on aortic peak flow velocity are as follows:
- Severe aortic stenosis is defined by a peak aortic velocity ≥4 m/s 2
- Moderate aortic stenosis is typically characterized by a peak aortic velocity <4 m/s, but the exact threshold can vary depending on the study and the specific criteria used 2, 3
- The diagnosis of aortic stenosis and its severity can be determined using echocardiography, which measures the peak aortic velocity, mean gradient, and aortic valve area (AVA) 4, 2, 5
Key Findings
- A study published in the European heart journal supplements found that severe aortic stenosis is defined by a mean gradient ≥40 mmHg, peak aortic velocity ≥4 m/s, and AVA ≤1 cm2 (or an indexed AVA ≤0.6 cm2/m2) 2
- Another study published in Open heart found that discordant grading in patients with moderate aortic stenosis is associated with higher mortality rates and lower aortic valve replacement rates 3
- A study published in Echocardiography found that an AVA value ≤0.81 cm2 or a Doppler velocity index ≤0.249 threshold carry the highest discriminative value for severe AS in patients with aortic stenosis 5