Guideline‑Referenced Criteria and Management of Aortic Stenosis

Definitions and Staging

• Stage A (at risk) – Patients with risk factors (e.g., bicuspid valve or aortic sclerosis) but no hemodynamic obstruction (Vmax < 2.0 m/s, no gradient) and no symptoms. American Heart Association recommendation. 1
• Stage B (progressive) – Mild‑to‑moderate aortic stenosis without symptoms; includes mild calcification or rheumatic changes. American Heart Association recommendation. 1
• Stage C1 (asymptomatic severe, normal LVEF) – Severe stenosis (Vmax ≥ 4.0 m/s or mean gradient ≥ 40 mm Hg; AVA ≤ 1.0 cm² or indexed AVA ≤ 0.6 cm²/m²) with preserved LVEF > 55 %. American Heart Association and American College of Cardiology recommendations. [1][2]
• Stage C2 (asymptomatic severe, reduced LVEF) – Same hemodynamic severity as C1 but LVEF < 50 %. American Heart Association recommendation. 1
• Stage D1 (symptomatic high‑gradient severe) – Symptomatic severe AS with high gradients (Vmax ≥ 4.0 m/s, mean gradient ≥ 40 mm Hg) and AVA ≤ 1.0 cm²; may have pulmonary hypertension. American Heart Association and American College of Cardiology recommendations. [1][2]
• Stage D2 (low‑flow, low‑gradient with reduced LVEF) – Symptomatic severe AS, AVA ≤ 1.0 cm², resting Vmax < 4.0 m/s or mean gradient < 40 mm Hg; true severity confirmed by low‑dose dobutamine stress echo (Vmax ≥ 4.0 m/s). American Heart Association and American College of Cardiology recommendations. [1][2]
• Stage D3 (paradoxical low‑flow, low‑gradient with normal LVEF) – Symptomatic severe AS, normal LVEF, AVA ≤ 1.0 cm², Vmax < 4.0 m/s, indexed AVA ≤ 0.6 cm²/m², stroke‑volume index < 35 mL/m²; small hypertrophied LV. American Heart Association and American College of Cardiology recommendations. [1][2]

Hemodynamic Criteria

Clinical Consequences

• Early LV diastolic dysfunction may appear already in progressive AS (stage B). American Heart Association recommendation. 1
• Mild LV hypertrophy is typical in asymptomatic severe AS with normal LVEF (stage C1). American Heart Association recommendation. 1
• In symptomatic high‑gradient severe AS (stage D1) pulmonary hypertension may be present. American Heart Association recommendation. 1
• Low‑flow, low‑gradient phenotypes (stages D2 and D3) are associated with LV diastolic dysfunction, LV hypertrophy, and in D2 also LVEF < 50 %. American Heart Association recommendation. 1

Prognosis

• Development of classic symptoms (heart failure, angina, syncope) in severe AS leads to rapid mortality without intervention; survival averages 2–3 years after symptom onset. American Heart Association recommendation. 1

Management Recommendations

Stage B (Progressive AS)

• No indication for aortic valve replacement (AVR). American Heart Association (Class III). 3
• Exercise testing is reasonable when symptom status is uncertain. American Heart Association recommendation. 1

Stage C1 (Asymptomatic Severe, Normal LVEF)

• Class I AVR if patient is undergoing another cardiac surgery. American Heart Association recommendation. 1
• Class IIa AVR if any of the following are present: peak velocity ≥ 5.0 m/s, abnormal exercise test (symptoms or hypotensive response), rapid progression (annual Vmax increase ≥ 0.3 m/s), or very low surgical risk. American Heart Association recommendation.

Stage C2 (Asymptomatic Severe, Reduced LVEF)

• Class I AVR regardless of symptoms; choice of surgical AVR or transcatheter AVR (TAVR) based on surgical risk. American College of Cardiology recommendation. 2

Stage D1 (Symptomatic High‑Gradient Severe)

• Class I AVR is mandatory. American Heart Association recommendation. 1
• Surgical AVR for low‑to‑moderate risk; TAVR for high or prohibitive risk. American College of Cardiology recommendation. 2

Stage D2 (Low‑Flow, Low‑Gradient with Reduced LVEF)

• Class IIa AVR if true severe AS is confirmed by low‑dose dobutamine stress echocardiography (Vmax ≥ 4.0 m/s) or CT calcium scoring showing severe calcification. American Heart Association recommendation. 1

Stage D3 (Paradoxical Low‑Flow, Low‑Gradient with Normal LVEF)

• Class IIa AVR only after careful confirmation of anatomic severity (CT calcium scoring) and attribution of symptoms to AS rather than comorbidities. American Heart Association and American College of Cardiology recommendations. [1][2]

Monitoring and Surveillance

• Aortic valve area calculated by the continuity equation. American Heart Association recommendation. 1
• Indexed AVA (≤ 0.6 cm²/m²) is essential for small‑body‑size patients. American Heart Association and American College of Cardiology recommendations. [1][2]
• Stroke‑volume index < 35 mL/m² defines low‑flow states. American Heart Association and American College of Cardiology recommendations. [1][2]
• BNP/NT‑proBNP elevation may signal hemodynamic decompensation even in asymptomatic patients. American Heart Association recommendation. 3
• Exercise testing is useful to unmask symptoms or abnormal hemodynamic response in asymptomatic patients. American Heart Association recommendation. 1
• Global longitudinal strain can detect subclinical myocardial dysfunction. American Heart Association recommendation. 3
• CT calcium scoring (>2000 Agatston units in men, >1200 in women) helps confirm severe AS in low‑gradient scenarios. American College of Cardiology recommendation.

Symptom Attribution

• Careful evaluation is required to differentiate AS‑related symptoms from common comorbidities (e.g., hypertension, coronary artery disease, atrial fibrillation). American College of Cardiology recommendation. 2

Aortic Stenosis Management Guidelines

Diagnosis and Staging

• The American College of Cardiology recommends classifying aortic stenosis into stages A through D based on valve anatomy, hemodynamics, left ventricular function, and symptom status, with Stage D patients requiring aortic valve replacement and earlier stages managed with surveillance 4, 5
• Patients with risk factors for developing aortic stenosis but no hemodynamic obstruction are classified as Stage A, with no indication for aortic valve replacement and surveillance every 3-5 years with echocardiography 6, 7
• Stage B patients have mild to moderate hemodynamic obstruction without symptoms, with no indication for aortic valve replacement and echocardiographic surveillance every 1-2 years for moderate disease, every 3-5 years for mild disease 6, 7

Treatment

• The American Heart Association recommends a Class IIa indication for aortic valve replacement in Stage C1 patients with peak velocity ≥5.0 m/s, abnormal exercise test, or rapid progression 7, 8
• Stage C2 patients have a Class I indication for aortic valve replacement regardless of symptoms 7
• Stage D1 patients have a Class I indication for aortic valve replacement, with average survival only 2-3 years without treatment 6, 9, 10
• Stage D2 patients require confirmation of severity with dobutamine stress echo or CT calcium scoring, with a Class IIa indication for aortic valve replacement if true severe aortic stenosis is confirmed 7, 8

Special Considerations

• The American College of Cardiology recommends using CT calcium scoring to confirm anatomic severity in Stage D3 patients, with a Class IIa indication for aortic valve replacement only after careful confirmation 7, 11
• Stage D3 patients require careful confirmation that aortic stenosis is severe and symptoms are attributable to aortic stenosis before considering aortic valve replacement 7, 12