When is surgery indicated for severe aortic stenosis (valve area ≤1.0 cm² or indexed ≤0.6 cm²/m²) based on symptoms, left‑ventricular ejection fraction <50 %, rapid progression, peak aortic jet velocity >5.0 m/s, abnormal stress‑test results, or associated severe valve disease?

When to Recommend Surgery in Aortic Stenosis

Surgery is mandatory for all symptomatic patients with severe aortic stenosis (valve area ≤1.0 cm² or indexed ≤0.6 cm²/m²), regardless of ejection fraction, as this represents a Class I indication with mortality approaching 50% at 2 years without intervention. 1, 2

Immediate Surgical Indications (Class I - Must Operate)

Symptomatic Severe AS

• Any valve-related symptoms mandate urgent aortic valve replacement (AVR): 1, 2
  • Exertional dyspnea or heart failure symptoms
  • Syncope or presyncope
  • Angina pectoris
• Delays in surgery lead to rapid clinical deterioration and high mortality risk 2

Asymptomatic Severe AS with High-Risk Features

• Left ventricular ejection fraction (LVEF) <50% without other explanation 1, 2, 3

  • This indicates LV systolic dysfunction from the stenosis itself
  • Surgery prevents irreversible myocardial damage 3

• Very severe hemodynamics (even if asymptomatic): 1, 2

  • Peak aortic jet velocity ≥5.0 m/s, OR
  • Mean gradient ≥60 mmHg
  • These patients have increased risk of sudden death 1

• Undergoing cardiac surgery for another indication 1, 2

  • Concomitant CABG, other valve surgery, or aortic surgery
  • Opportunity to address the stenosis simultaneously

Strong Consideration for Surgery (Class IIa - Should Operate)

Asymptomatic Severe AS with Abnormal Exercise Testing

• Positive exercise stress test revealing: 2, 3
  • Development of symptoms during supervised testing
  • Fall in systolic blood pressure below baseline (>10 mmHg drop) 1, 4
  • Complex ventricular arrhythmias
• Exercise testing unmasks occult symptoms and abnormal hemodynamic responses 2, 3

Asymptomatic Severe AS with Rapid Progression

• Rapid increase in peak velocity ≥0.3 m/s per year with moderate-to-severe valve calcification 1, 2, 3
• Indicates aggressive disease course requiring preemptive intervention 2

Asymptomatic Severe AS with Severe LV Dilation

• Left ventricular end-systolic dimension (LVESD) >50 mm or indexed LVESD >25 mm/m² 1
• Severe LV dilation predicts worse outcomes if surgery is delayed 1

May Consider Surgery (Class IIb - Reasonable in Select Cases)

Low Surgical Risk with Progressive Changes

• Progressive decline in LVEF to low-normal range (55-60%) on ≥3 serial studies 1
• Progressive LV end-diastolic dimension (LVEDD) >65 mm 1
• Only consider when surgical risk is low and patient has good life expectancy 1

Excessive LV Hypertrophy

• Marked LV hypertrophy without history of hypertension 1, 2
• Suggests severe afterload from the stenosis itself 2

Special Scenarios Requiring Careful Assessment

Low-Flow, Low-Gradient AS with Reduced LVEF (<50%)

• Dobutamine stress echocardiography is essential to differentiate: 1, 2

  • True-severe AS: Valve area remains ≤1.0 cm² at all flow rates, peak velocity ≥4.0 m/s or mean gradient ≥30-40 mmHg with augmented flow 1
  • Pseudo-severe AS: Valve area increases to >1.0 cm² with increased flow 1

• Presence of contractile reserve (>20% increase in stroke volume): 1

  • Predicts better surgical outcomes
  • Surgery still recommended even without contractile reserve, though operative mortality is higher 1, 5

• Absence of contractile reserve: 1, 5

  • High surgical mortality (33% in historical series) 5
  • However, survivors show significant symptomatic improvement 5
  • AVR still recommended as medical management has worse outcomes 6, 5

Paradoxical Low-Flow, Low-Gradient AS with Preserved LVEF (≥50%)

• Diagnosis requires careful exclusion of technical errors and confirmation of: 1

  • Stroke volume index <35 mL/m²
  • Mean gradient 30-40 mmHg (when normotensive)
  • Valve area ≤0.8 cm²
  • Heavy valve calcification on CT (men ≥2000, women ≥1200 Agatston units) 1

• Surgery is appropriate when clinical and imaging data support true-severe disease 1

Critical Pitfalls to Avoid

Never Delay Surgery in Symptomatic Patients

• Medical therapy does NOT improve outcomes in symptomatic severe AS 2
• Medical management is reserved only for inoperable patients 2
• Vasodilators (ACE inhibitors, ARBs) can cause profound hypotension in severe AS 2, 7

Do Not Withhold Surgery Based on Low LVEF Alone

• Even severely depressed LVEF (<30%) improves after AVR 7, 6
  • 1-year survival post-AVR: 92% 7
  • LVEF typically increases by 10 percentage points 7
  • LVEF may normalize if afterload mismatch was the primary cause 7, 6
• TAVR shows better LVEF recovery than SAVR in patients with reduced systolic function 6

Do Not Operate Based on Valve Area Alone in Asymptomatic Patients

• Combination of severe stenosis PLUS symptoms, LV dysfunction, or abnormal exercise response is required 3
• Truly asymptomatic patients with preserved LVEF and normal exercise tolerance have good short-term prognosis with surveillance 3

Do Not Miss the Window for Surgery

• Once LVEF drops below 50%, irreversible LV dysfunction can develop if surgery is postponed 3
• Serial echocardiography every 6-12 months is essential for asymptomatic patients 2, 3

Surveillance Protocol for Asymptomatic Patients Not Yet Meeting Surgical Criteria

• Serial echocardiography monitoring: 2, 3

  • LVEF assessment
  • LV dimensions (LVEDD, LVESD)
  • Peak velocity and mean gradient
  • Rate of progression

• Exercise stress testing to confirm truly asymptomatic status 2, 3

  • Supervised testing in experienced centers
  • Unmasks occult symptoms or abnormal hemodynamic responses

• Patient education to report new symptoms immediately 2

  • Even subtle symptoms constitute indication for urgent intervention

Contraindications to Surgery

Absolute contraindications (Class III - Do Not Operate): 2

• Life expectancy <1 year due to non-cardiac comorbidities
• Severe non-cardiac comorbidities unlikely to improve with AVR
• Moderate-to-severe dementia
• End-stage organ failure (renal, hepatic, pulmonary, malignancy)
• Severe frailty (bed-bound, cachexia, inability to perform activities of daily living)