From the Guidelines
The diagnostic criteria for aortic stenosis include a reduced aortic valve area (less than 1.0 cm²), increased transvalvular gradient (mean gradient greater than 40 mmHg), and decreased valve mobility, with severe aortic stenosis defined as an aortic valve area less than 1.0 cm², mean gradient greater than 40 mmHg, or peak jet velocity greater than 4.0 m/s, as recommended by the European Association of Cardiovascular Imaging and the American Society of Echocardiography 1.
Diagnostic Approach
The diagnosis of aortic stenosis is based on an integrated approach including:
- Transvalvular velocity/gradient
- Valve area
- Valve morphology
- Flow rate
- LV morphology and function
- Blood pressure
- Symptoms
Echocardiography
Echocardiography is the primary diagnostic tool, providing assessment of valve morphology, calcification, and hemodynamic parameters, with a step-by-step approach recommended to deal with the challenge of defining severe aortic stenosis in clinical practice 1.
Classification of Severe Aortic Stenosis
Severe aortic stenosis is classified based on the combination of velocity (gradient), transvalvular SV, and LV ejection fraction, with high gradient (velocity > 4 m/s or mean gradient > 40 mmHg) vs. low gradient (mean gradient < 40 mmHg), normal flow (SVi > 35 mL/m2) vs. low flow (SVi < 35 mL/m2), and preserved ejection fraction (≥ 50%) vs. reduced ejection fraction (< 50%) 1.
Additional Diagnostic Modalities
Additional diagnostic modalities include cardiac catheterization, CT scanning, and MRI, which can provide complementary information about valve anatomy and function, with early diagnosis crucial as untreated severe symptomatic aortic stenosis carries a poor prognosis with mortality rates of approximately 50% at two years after symptom onset 1.
From the Research
Diagnostic Criteria for Aortic Stenosis
The diagnostic criteria for aortic stenosis involve a combination of physical examination, echocardiography, and other imaging techniques. The key parameters used to diagnose and assess the severity of aortic stenosis include:
- Peak instantaneous velocity
- Mean gradient
- Effective orifice area
- Left ventricular (LV) dimensions and systolic function
- Aortic diameter
- Mitral valve appearance and function
- Right ventricular (RV) size and function
- Pulmonary artery (PA) pressure 2
Role of Echocardiography
Echocardiography plays a central role in the diagnosis and assessment of aortic stenosis. It can be used to evaluate the aortic valve, left ventricle, and other cardiac structures. Transthoracic echocardiography (TTE) and transoesophageal echocardiography (TOE) are commonly used to assess aortic valve stenosis 3
Comparison with Other Imaging Techniques
Cardiac magnetic resonance (CMR) imaging has been shown to be as accurate as echocardiography in assessing aortic valve stenosis. CMR has better inter- and intraobserver reliability and demonstrates an advantage over echocardiography in the detection of severe aortic stenosis with greater specificity and sensitivity 3
Diagnostic Approach
The diagnostic approach for aortic stenosis typically involves:
- Initial screening using physical examination and focused cardiac ultrasound (FoCUS)
- Referral for standard echocardiography if abnormal findings are present
- Use of visual AS and calcification scores as objective parameters in screening for aortic stenosis with FoCUS 4
- Consideration of other imaging techniques, such as CMR, in certain cases 3