How should aortic stenosis be managed according to severity, symptom status, and surgical risk?

Management of Aortic Stenosis

Symptomatic patients with severe aortic stenosis require urgent aortic valve replacement (AVR), as this is a Class I indication with mortality rates approaching 50% at 2 years without intervention. 1

Defining Severe Aortic Stenosis

Severe aortic stenosis is diagnosed when any of the following criteria are met 2, 1:

• Aortic valve area ≤1.0 cm² (or indexed <0.6 cm²/m² BSA)
• Mean gradient ≥40 mmHg
• Peak velocity ≥4.0 m/s

Transthoracic echocardiography with Doppler is the cornerstone diagnostic test for initial evaluation and severity assessment 3.

Management Algorithm by Clinical Presentation

Symptomatic Severe AS: Immediate Intervention Required

Any valve-related symptoms mandate urgent AVR 1:

• Exertional dyspnea or heart failure
• Syncope or presyncope
• Angina pectoris

The choice between transcatheter aortic valve replacement (TAVR) and surgical aortic valve replacement (SAVR) depends on multiple factors 3, 4:

Age-based approach 3:

• <65 years: SAVR preferred
• 65-75 years: SAVR generally preferred over TAVR
• 75-80 years: Either SAVR or TAVR acceptable
• >80 years: TAVR preferred

Surgical risk stratification using STS-PROM 3:

• **Low risk (STS-PROM <4%): SAVR preferred**, especially if life expectancy >30 years
• Intermediate risk (STS-PROM 4-8%): Either SAVR or TAVR acceptable after Heart Team discussion
• High risk (STS-PROM ≥8%): TAVR preferred
• Prohibitive risk (>50% mortality risk): TAVR only option 3

Additional factors favoring TAVR 3, 4:

• Porcelain aorta or hostile chest
• Significant frailty or disability
• Multiple comorbidities
• Prior chest radiation

Additional factors favoring SAVR 3:

• Concomitant valve disease requiring surgery
• Coronary artery disease requiring CABG
• Ascending aorta pathology
• Bicuspid aortic valve
• Aortic root anatomy unfavorable for TAVR (excessive calcification, annulus size out of range)

Asymptomatic Severe AS: Selective Intervention

Class I indications for intervention in asymptomatic patients 4, 1:

• LV systolic dysfunction (LVEF <50%) without other explanation
• Undergoing cardiac surgery for another indication
• Very severe AS (peak velocity ≥5.0 m/s or mean gradient ≥60 mmHg)

Class IIa indications (strong consideration for surgery) 1:

• Abnormal exercise stress test showing symptoms, fall in blood pressure below baseline, or complex ventricular arrhythmias
• Rapid progression (peak velocity increase ≥0.3 m/s per year) with moderate-to-severe calcification
• Markedly elevated BNP levels (>3 times normal) without other explanation
• Ascending aorta dilation >50 mm (or >27.5 mm/m² BSA)

Surveillance strategy for truly asymptomatic patients with preserved LVEF 1:

• Serial echocardiography monitoring LV function
• Patient education to report new symptoms immediately
• Exercise testing to unmask occult symptoms 3

Special Scenarios: Low-Flow Low-Gradient AS

Classical LFLG AS (reduced LVEF <50%) 3:

• Perform dobutamine stress echocardiography to differentiate true-severe from pseudo-severe AS
• If flow reserve present and truly severe AS confirmed: AVR recommended 4
• If pseudo-severe AS: medical management for underlying cardiomyopathy 2

Paradoxical LFLG AS (preserved LVEF ≥50%) 3:

• More challenging diagnosis requiring multimodality imaging
• Consider CT calcium scoring (Agatston score >2000 in women, >3000 in men suggests severe AS)
• AVR reasonable if truly severe AS confirmed

Contraindications to Intervention

Absolute contraindications 3:

• Life expectancy <1 year from comorbidities
• Severe comorbidities unlikely to improve quality of life or survival
• Moderate-to-severe dementia
• End-stage organ failure (renal, liver, lung disease, or malignancy)
• Severe frailty limiting likelihood of functional recovery (bedbound, cachexia/severe sarcopenia, disability for most ADLs)

All decisions regarding intervention contraindications require Heart Team discussion with shared decision-making incorporating patient preferences and values 3.

Perioperative Management for Noncardiac Surgery

Symptomatic severe AS requiring noncardiac surgery 3:

• High-risk noncardiac surgery: Consider AVR before elective surgery to reduce perioperative risk
• Urgent noncardiac surgery: Consider balloon aortic valvuloplasty as bridge to definitive treatment
• Alternative: Proceed with elevated-risk surgery after shared decision-making, considering nonsurgical management or minimally invasive alternatives

Asymptomatic severe AS with LVEF ≥50% requiring noncardiac surgery 3:

• Low-risk noncardiac surgery: Reasonable to proceed with careful hemodynamic monitoring
• Avoid hypotension, excessive hypertension, and tachycardia during procedure
• Elevated-risk noncardiac surgery: Evaluate for AVR before elective surgery if patient meets criteria for intervention

Critical Pitfalls to Avoid

Never delay surgery for medical optimization in symptomatic patients 1. Medical therapy does not alter the natural history of severe AS and is reserved only for non-operable patients 1.

Use vasodilators (ACE inhibitors, ARBs) with extreme caution in severe AS due to risk of substantial hypotension 1.

Do not perform TAVR for moderate AS outside of concomitant cardiac surgery, as all evidence and guidelines restrict TAVR to severe AS only 2.

Avoid misclassifying symptomatic status or hemodynamic severity, as studies show 56% of symptomatic patients are inappropriately denied intervention due to overestimation of operative risk or misclassification 5.

Mild-to-Moderate AS Management

Conservative management with surveillance 2:

• Serial echocardiography every 1-2 years for moderate AS
• Serial echocardiography every 3-5 years for mild AS
• Intervention only indicated if progression to severe AS with symptoms or other Class I indications