What is the management approach for patients with moderate to severe Aortic Stenosis (AS)?

Management of Moderate to Severe Aortic Stenosis

For symptomatic patients with severe AS, aortic valve replacement (AVR) by either surgical or transcatheter approach is mandatory and should be performed promptly, as survival without intervention drops to 2-3 years after symptom onset. 1, 2

Severity Classification and Diagnostic Approach

Severe AS is defined by:

• Aortic valve area <1.0 cm² 1, 2
• Mean pressure gradient ≥40 mmHg 1, 2
• Peak aortic jet velocity ≥4.0 m/s 1, 2

Moderate AS is defined by:

• Aortic jet velocity 3.0-3.9 m/s 1
• Valve area typically 1.0-1.5 cm² 1

Transthoracic echocardiography is the primary diagnostic tool and sufficient for guiding management in 65-70% of patients. 2 When measurements are discordant or obtained during hypertension, repeat assessment when normotensive is essential to avoid underestimating severity. 1

Management Algorithm Based on Symptom Status

Symptomatic Severe AS (Stage D1)

AVR is Class I indication (must be performed) for all symptomatic patients with severe high-gradient AS. 1 This includes patients with:

• Heart failure symptoms 1
• Exertional dyspnea 1
• Syncope or presyncope 1
• Angina 1
• Symptoms documented on exercise testing 1

Without intervention, average survival is only 2-3 years once symptoms develop, with sudden death being a major concern. 1, 2 Age alone is not a contraindication to surgery. 1

Asymptomatic Severe AS (Stage C)

AVR is Class I indication (must be performed) if:

• Left ventricular ejection fraction <50% (Stage C2) 1, 3
• Patient is undergoing other cardiac surgery 1

AVR is Class IIa indication (reasonable to perform) if:

• Very severe AS with peak velocity ≥5.0 m/s AND low surgical risk 1
• Decreased exercise tolerance or exercise-induced fall in blood pressure on stress testing 1, 3
• Rapid disease progression (velocity increase ≥0.3 m/s per year) 3

Watchful waiting with close surveillance is appropriate for truly asymptomatic patients with:

• Preserved LVEF ≥50% 3
• Good exercise tolerance 3
• No high-risk features 3

The risk of sudden death in truly asymptomatic patients followed prospectively is low (<1% per year), supporting conservative management with close monitoring. 1, 3

Moderate AS (Stage B)

AVR is Class IIa indication (reasonable) if:

• Patient is undergoing other cardiac surgery 1

Otherwise, medical management and surveillance are appropriate, with intervention reserved for progression to severe AS or symptom development. 1

Special Diagnostic Scenarios

Low-Flow, Low-Gradient Severe AS with Reduced LVEF (Stage D2)

When severe AS is suspected but velocity <4.0 m/s or mean gradient <40 mmHg with LVEF <50%:

Dobutamine stress echocardiography (up to 20 mcg/kg/min) is Class IIa indication to:

• Distinguish true severe AS from pseudo-severe AS 1, 4, 2
• Assess contractile reserve 1

True severe AS is confirmed when:

• Aortic velocity increases to ≥4.0 m/s (or mean gradient ≥40 mmHg) at any flow rate 1
• Valve area remains ≤1.0 cm² despite increased flow 1

AVR is reasonable if true severe AS is confirmed with contractile reserve present. 1, 2

Alternative confirmatory tests (Class IIa):

• Aortic valve calcium score by CT imaging 1, 2
• Velocity ratio (LVOT/aortic velocity) ≤0.25 1

Low-Flow, Low-Gradient Severe AS with Normal LVEF (Stage D3)

AVR is reasonable in symptomatic patients who are normotensive with LVEF ≥50% if clinical, hemodynamic, and anatomic data support valve obstruction as the primary cause of symptoms. 1 Multi-slice CT for calcium scoring is particularly useful in this scenario. 2

Intervention Selection: SAVR vs TAVI

Decision-making requires Heart Team evaluation including:

• Cardiologists with valvular expertise 2
• Structural interventional cardiologists 2
• Cardiovascular surgeons 2
• Imaging specialists 2

Surgical risk stratification using STS-PROM score:

• Low risk (<4%): SAVR is generally preferred, especially in younger patients 2
• Intermediate risk (4-8%): Either SAVR or TAVI based on patient factors 2
• High risk (>8%): TAVI is generally preferred 2

Additional factors favoring TAVI:

• Porcelain aorta or hostile chest anatomy 4
• Multiple comorbidities 4
• Frailty or disability 4
• Oxygen-dependent lung disease 4

Additional factors favoring SAVR:

• Younger age with long life expectancy 4
• Concomitant coronary artery disease requiring CABG 2
• Other significant valve disease requiring surgery 2

Surveillance Protocol for Asymptomatic Patients

Echocardiographic monitoring intervals:

• Severe AS: Every 6-12 months 5
• Moderate AS: Every 1-2 years 5
• Mild AS: Every 3-5 years 5

Exercise stress testing should be performed to:

• Confirm truly asymptomatic status 3
• Unmask occult symptoms 2, 3
• Document abnormal hemodynamic responses 3

Surgery is indicated if exercise testing reveals:

• Development of symptoms 1, 3
• Fall in systolic blood pressure (rise <20 mmHg or any decrease) 1, 3
• Complex ventricular arrhythmias 1, 3
• Failure to reach 80% of age-predicted exercise capacity 1

Management of Critically Ill Patients

For patients presenting with cardiogenic shock from critical AS:

• Balloon aortic valvuloplasty (BAV) is recommended as a bridge to definitive treatment 4
• After stabilization with BAV, proceed to TAVI or SAVR based on risk assessment 4
• Close hemodynamic monitoring is essential during and after intervention 4

Medical Management

No medical therapy prevents or slows AS progression. Statins do not prevent disease progression based on three large randomized controlled trials. 1

Medical management focuses on:

• Careful blood pressure control (target systolic 100-120 mmHg in acute settings) 2
• Heart rate control to avoid both bradycardia and tachycardia 2
• Beta-blockers are preferred for blood pressure control 2
• Treatment of concurrent hypertension, atrial fibrillation, and coronary artery disease 5

Observational data suggest potential benefit from:

• Beta-blocker use (RR 0.52 for mortality) 6
• Statin use (RR 0.52 for mortality) 6

Critical Pitfalls to Avoid

Do not delay intervention once symptoms develop - mortality increases dramatically without prompt AVR. 1, 2

Do not delay surgery if LVEF drops below 50% - irreversible LV dysfunction can develop. 3

Do not rely solely on gradients in low-flow states - valve area calculation and alternative confirmatory tests are essential. 1, 4

Do not miss symptoms in elderly patients - reduced mobility and comorbidities may mask symptoms; exercise testing is crucial. 2, 3

Do not perform measurements during hypertension - this may underestimate stenosis severity; repeat when normotensive. 1

Consider medical futility in patients with life expectancy <1 year or moderate-to-severe dementia before proceeding with intervention. 4, 2

Preoperative Evaluation

Mandatory assessments before intervention:

• Coronary angiography (CAD present in 40-75% of AS patients) 2
• Dental evaluation with treatment of acute issues to prevent prosthetic valve endocarditis 2
• Assessment for concurrent valvular disease, LV dysfunction, and pulmonary hypertension 2
• Carotid ultrasound when indicated 2
• Documentation of contrast/latex allergies 2