From the Guidelines
Aortic stenosis is diagnosed based on clinical symptoms, physical examination findings, and echocardiographic criteria, with severe aortic stenosis defined as valve area less than 1.0 cm², mean pressure gradient greater than 40 mmHg, and peak jet velocity greater than 4.0 m/s, as recommended by the most recent guidelines 1. The diagnostic criteria for aortic stenosis involve a combination of clinical and echocardiographic assessments. Key criteria include:
- Valve area less than 1.0 cm²
- Mean pressure gradient across the valve greater than 40 mmHg
- Peak jet velocity greater than 4.0 m/s Severe aortic stenosis is characterized by these criteria, while moderate stenosis involves valve area between 1.0-1.5 cm², mean gradient of 20-40 mmHg, and peak velocity of 3.0-4.0 m/s, and mild stenosis is characterized by valve area greater than 1.5 cm², mean gradient less than 20 mmHg, and peak velocity less than 3.0 m/s 1. In patients with low-gradient aortic stenosis, additional assessments such as dobutamine stress echocardiography and noncontrast computed tomography (CT) aortic valve calcium scoring may be necessary to determine the severity of the stenosis, as recommended by the guidelines 1. The diagnosis of severe aortic stenosis must be based on an integrated approach including transvalvular velocity/gradient, valve area, valve morphology, flow rate, LV morphology and function, blood pressure, and symptoms, as emphasized by the European Association of Cardiovascular Imaging and the American Society of Echocardiography 1. Clinical symptoms typically develop when stenosis becomes severe and include angina, syncope, and heart failure, while physical examination may reveal a harsh systolic murmur at the right upper sternal border with radiation to the carotids, diminished or delayed carotid upstroke, and a sustained apical impulse 1. These criteria help determine disease severity and guide treatment decisions, with severe symptomatic aortic stenosis generally requiring valve replacement, as recommended by the guidelines 1.
From the Research
Diagnostic Criteria for Aortic Stenosis
The diagnostic criteria for aortic stenosis can be defined into four broad categories:
- High-gradient AS: mean gradient ≥ 40 mmHg, peak velocity ≥ 4 m/s, aortic valve area (AVA) ≤ 1 cm2 or indexed AVA ≤ 0.6 cm2/m2 2
- Low-flow, low-gradient AS with reduced ejection fraction: mean gradient < 40 mmHg, AVA ≤ 1 cm2, left ventricle ejection fraction (LVEF) < 50%, stroke volume index (SVi) ≤ 35 mL/m2 2
- Low-flow, low-gradient AS with preserved ejection fraction: mean gradient < 40 mmHg, AVA ≤ 1 cm2, LVEF ≥ 50%, SVi ≤ 35 mL/m2 2
- Normal-flow, low-gradient AS with preserved ejection fraction: mean gradient < 40 mmHg, AVA ≤ 1 cm2, indexed AVA ≤ 0.6 cm2/m2, LVEF ≥ 50%, SVi > 35 mL/m2 2
Hemodynamic Parameters
The diagnosis of severe AS is currently based on three hemodynamic parameters:
- Maximal jet velocity
- Mean pressure gradient (mPG) across the aortic valve
- Aortic valve area (AVA) 3 However, inconsistent grading of AS severity is common when the AVA is < 1.0 cm2 but the mPG is < 40 mmHg, also known as low-gradient AS (LGAS) 3, 4
Echocardiographic Evaluation
Echocardiography plays a central role in providing a comprehensive morphological and hemodynamic evaluation of AS 3, 5 Stress echocardiography testing plays an important role in the evaluation of low-gradient AS, particularly in patients with symptomatic LGAS with low stroke volume and/or low ejection fraction 2, 3, 6