Which echocardiogram measurements define severe aortic stenosis for TAVR eligibility?

✓ Accepted answer

Severe aortic stenosis is defined by a combination of echocardiographic measurements, most critically a maximal aortic jet velocity of 4 m/s or higher, a mean transvalvular gradient of 40 mmHg or more, and a calculated aortic valve area of 1.0 cm² or less.

• Valve Area Thresholds: The absolute aortic valve area must be 1.0 cm² or lower. For patients with small left ventricular volumes, clinicians also use the indexed area; a value of 0.6 cm²/m² or less confirms severe disease regardless of absolute size.
• Pressure Gradients and Velocity: A mean pressure gradient of at least 40 mmHg is a standard diagnostic criterion. Additionally, the peak aortic jet velocity measured by Doppler ultrasound must reach 4 m/s or greater to classify the stenosis as severe.
• Special Clinical Contexts: In patients with low flow and low gradients, such as those with a reduced ejection fraction, the severity can be masked. In these specific cases, a dobutamine stress echocardiogram may be required to verify the true degree of stenosis before proceeding.
• Symptomatic Status: TAVR eligibility typically requires that the severe stenosis is causing symptoms (such as shortness of breath or chest pain) or that the left ventricular ejection fraction has dropped below 50%.
• Anatomical Suitability: Beyond valve measurements, the patient's aortic root anatomy and femoral artery access must meet specific device requirements. Current guidelines also favour TAVR for patients aged 80 and older, while those aged 60 to 79 generally require a shared decision between the patient and their heart team.

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