Aortic stenosis

American College of Cardiology/American Heart Association (ACC/AHA) classification of stages of valvular AS (2020)[26]Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA guideline for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Joint Committee on clinical practice guidelines. Circulation. 2021 Feb 2;143(5):e72-227. https://www.ahajournals.org/doi/full/10.1161/CIR.0000000000000923

Stage A: at risk of AS

• Valve anatomy: bicuspid aortic valve or other congenital valve anomaly, or aortic valve sclerosis

• Maximum aortic velocity <2 m/s

• No hemodynamic consequences

• No symptoms

Stage B: Progressive AS

• Valve anatomy of mild-to-moderate leaflet calcification of a bicuspid or trileaflet valve with some reduction in systolic motion, or rheumatic valve with commissural fusion

• Mild AS: maximum aortic velocity 2.0 to 2.9 m/s or mean pressure gradient <20 mmHg

• Moderate AS: maximum aortic velocity 3.0 to 3.9 m/s or mean pressure gradient 20-39 mmHg

• Hemodynamic consequences: normal left ventricular ejection fraction (LVEF); early left ventricular (LV) diastolic dysfunction may be present

• No symptoms

Stage C: Asymptomatic severe AS

• Anatomy shows severe leaflet calcification or congenital stenosis with severely reduced leaflet opening

• Maximum aortic velocity ≥4 m/s or mean pressure gradient ≥40 mmHg

• Valve area typically ≤1.0 cm² (or indexed valve area ≤0.6 cm²/m²)

• Very severe AS: maximum aortic velocity ≥5 m/s or mean pressure gradient ≥60 mmHg

• Hemodynamic consequences:

  • Stage C1: mild LV diastolic dysfunction, mild left ventricular hypertrophy (LVH), normal LVEF

  • Stage C2: LVEF <50%

• No symptoms

  • Exercise testing is reasonable to confirm lack of symptoms in stage C1 AS

Stage D: Symptomatic severe AS

• Stage D1: Symptomatic severe high-gradient AS

  • Anatomy: severe leaflet calcification or congenital stenosis with severely reduced leaflet opening

  • Maximum aortic velocity ≥4 m/s or mean pressure gradient ≥40 mmHg

  • Valve area typically ≤1.0 cm² (or indexed valve area ≤0.6 cm²/m²), but may be larger with mixed AS/aortic regurgitation

  • Hemodynamic consequences: LV diastolic dysfunction and LVH; pulmonary hypertension may be present

  • Symptoms of exertional dyspnea or decreased exercise tolerance, exertional angina, exertional syncope or presyncope

• Stage D2: Symptomatic severe low-flow/low-gradient AS with reduced LVEF

  • Anatomy: severe leaflet calcification/fibrosis with severely reduced leaflet motion

  • Valve area ≤1.0 cm² with resting maximum aortic velocity <4 m/s or mean pressure gradient <40 mmHg

  • Dobutamine stress echo shows valve area ≤1.0 cm² with maximum aortic velocity ≥4 m/s at any flow rate

  • Hemodynamic consequences: LV diastolic dysfunction, LVH, and LVEF <50%

  • Symptoms of heart failure, angina, syncope, or presyncope

• Stage D3: Symptomatic severe low-gradient AS with normal LVEF or paradoxical low-flow severe AS

  • Anatomy: severe leaflet calcification with severely reduced leaflet motion

  • Valve area ≤1.0 cm² (indexed valve area ≤0.6 cm²/m²) with maximum aortic velocity <4 m/s or mean pressure gradient <40 mmHg AND stroke volume index <35 mL/m² measured when patient is normotensive (systolic blood pressure <140 mmHg)

  • Hemodynamic consequences: increased LV wall thickness, small LV chamber with low stroke volume, restrictive diastolic filling, and LVEF ≥50%

  • Symptoms of heart failure, angina, syncope, or presyncope

The National Institute for Health and Care Excellence (NICE) in the UK

NICE recommends that severity of valve disease should be defined in line with the British Society of Echocardiography (BSE) guidelines on the assessment of AS.[28]National Institute for Health and Care Excellence. Heart valve disease presenting in adults: investigation and management. Nov 2021 [internet publication]. https://www.nice.org.uk/guidance/ng208 ​ In general, the BSE advise:[43]Zoghbi WA, Chambers JB, Dumesnil JG, et al. Recommendations for evaluation of prosthetic valves with echocardiography and doppler ultrasound. J Am Soc Echocardiogr. 2009 Sep;22(9):975-1014. https://onlinejase.com/article/S0894-7317(09)00676-2/fulltext ​​

• Maximal velocity is the preferred measure with which to define severity of AS.

• If either the aortic valve maximal velocity (AV Vmax) is ≥4 m/s or the mean aortic valve gradient is ≥40 mmHg, the patient should usually be considered to have severe AS. However, the BSE does list exceptions to this statement, such as scenarios where this increased blood flow (e.g., tachyarrhythmias or sepsis).

• Very severe AS is defined as an AV Vmax ≥5 m/s or a mean gradient ≥60 mmHg.