2017 ACC/AATS/AHA AUC for Severe Aortic Stenosis

AUC Rating System

All clinical recommendations are classified on a 9-point scale divided into three levels of appropriateness. This system balances evidence, clinical experience, procedural risk, and patient outcomes.

7–9: Appropriate

Treatment is generally acceptable and is a reasonable approach. The benefits exceed potential negative consequences.

4–6: May Be Appropriate

Treatment may be generally acceptable. Benefits may outweigh risks; additional clinical judgment and individual circumstances matter.

1–3: Rarely Appropriate

Treatment is not generally acceptable. Risks outweigh benefits, or insufficient evidence supports use.

Key Point: An Appropriate rating reflects current evidence at guideline publication. Ratings may evolve as new data emerge. Rarely Appropriate does not prohibit a procedure if clinical judgment strongly supports individualized patient care.

Aortic Stenosis Severity Classification

Severe aortic stenosis is diagnosed when all three criteria are met at normal or near-normal cardiac output:

Peak Aortic Valve Velocity Vmax ≥ 4 m/s

Mean Aortic Gradient Mean ≥ 40 mmHg

Aortic Valve Area AVA <1.0 cm² or AVA/BSA <0.6 cm²/m²

Pitfall: Do not rely on a single parameter. Measure all three (velocity, gradient, area) and verify consistency. Discordant results may indicate pseudosevere or truly severe AS with unusual hemodynamics.

Special Definitions

Term	Definition
High-Gradient AS	Severe AS (Vmax ≥4 m/s, AVA <1.0 cm²) with mean gradient ≥40 mmHg; most common
Low-Flow, Low-Gradient AS	AVA <1.0 cm², mean gradient <40 mmHg, reduced flow (SVI <35 mL/m²)
Dobutamine Stress Echo	Used in low-flow scenarios to distinguish truly severe from pseudosevere AS

Surgical Risk Stratification

All patients with severe AS should have risk assessment using EuroSCORE II or STS-PROM. Risk category drives treatment recommendations and guides SAVR vs TAVR selection.

Risk Category	Score	Clinical Characteristics
Low Risk	STS <3%	Age <70, preserved EF, no major comorbidities, elective surgery candidate
Intermediate Risk	STS 3–8%	Age 70–85, moderate comorbidities, LVEF 30–50%
High or Extreme Risk	STS >8%	Age >85, frailty, porcelain aorta, hostile chest, LVEF <30%, advanced liver disease

Clinical Context: Risk assessment includes STS-PROM calculation plus qualitative factors: frailty, porcelain aorta, hostile chest, advanced liver disease, dementia, anticipated life expectancy. Heart Valve Team discussion is essential for high-risk or complex cases.

Flow and Gradient Classification

Flow state and gradient help determine treatment approach, especially in borderline or discordant cases.

Metric	Normal	Low/Reduced
Stroke Volume Index (SVI)	≥35 mL/m²	<35 mL/m² indicates low flow state
Left Ventricular Ejection Fraction (LVEF)	Preserved ≥50%	Reduced <50%; severe if <20%
Flow Reserve on Dobutamine	Increase in SVI >20% suggests pseudosevere	Persistent reduced AVA despite increased flow = truly severe

Decision Pathway for Low-Flow Scenarios

Approach to Low-Flow, Low-Gradient AS

Step 1: Confirm reduced flow (SVI <35 mL/m²) and low gradient (mean <40 mmHg). Verify with repeat echocardiography.

Step 2: Perform dobutamine stress echocardiography to assess flow reserve and change in AVA.

Step 3a: Flow reserve, AVA increases >1.0 cm² = Pseudosevere AS. Consider medical management.

Step 3b: Persistent low AVA <1.0 cm² despite flow increase = Truly severe AS. Offer intervention if symptomatic or EF <20%.

Asymptomatic, High-Gradient Severe AS

Patients with severe AS who are asymptomatic require risk stratification and surveillance vs. intervention decision-making.

Key Finding: In asymptomatic patients with normal exercise stress test and preserved EF, intervention is generally Rarely Appropriate. However, if symptoms develop or adverse prognostic markers emerge (rapidly worsening gradient, LV dysfunction), intervention becomes Appropriate.

Appropriateness by Surgical Risk

Clinical Scenario	No Intervention	AVR/TAVR
Asymptomatic, LVEF ≥50%, Normal stress test, Low risk	M (4)	A (7)
Asymptomatic, LVEF ≥50%, Negative stress test, Intermediate risk	A (7)	M (5)
Asymptomatic, LVEF ≥50%, Abnormal stress test, Low-to-Intermediate risk	M (4)	A (7)
Asymptomatic, LVEF <50%, Any test, Low-to-Intermediate risk	M (4)	A (7)

DO:

Perform exercise stress testing in all asymptomatic patients
Monitor for symptom onset (exertional dyspnea, chest discomfort, presyncope)
Assess for rapid progression (Vmax increase >0.3 m/s/year)
Consider intervention if LVEF declines <50% or severe pulmonary hypertension develops

Symptomatic, High-Gradient Severe AS

Symptomatic severe AS is an indication for valve replacement. The choice between SAVR and TAVR depends on age, surgical risk, anatomic suitability, and patient preference.

SAVR vs TAVR by Surgical Risk Profile

Surgical Risk	Age / Fitness	SAVR	TAVR
Low Risk	<75 yrs, good functional status	A (8)	M (5)
Intermediate Risk	75–85 yrs or moderate comorbidities	A (8)	A (7)
High/Extreme Risk	>85 yrs, frailty, or STS >8%	M (5)	A (8)

Heart Valve Team Decision: Final choice between SAVR and TAVR incorporates procedural risk (STS-PROM, frailty), anatomic factors (aortic root, sinuses of Valsalva, ascending aorta, coronary ostia, calcification), durability goals, access availability, and patient preference.

Symptomatic AS with Reduced Ejection Fraction

LVEF Status	SAVR	TAVR
LVEF 30–50%, Symptomatic	A (7)	A (7)
LVEF <30%, Symptomatic, Low-Intermediate Risk	A (8)	M (5)
LVEF <30%, Symptomatic, High Risk	M (5)	A (7)

Low-Flow and Low-Gradient Aortic Stenosis

Low-flow, low-gradient scenarios (AVA <1.0 cm², mean gradient <40 mmHg, reduced EF or SVI) require dobutamine stress echocardiography to distinguish truly severe from pseudosevere AS.

Management of Reduced EF with AS

Step 1 – Confirm: Measure AVA, calculate SVI, document LVEF <50%.

Step 2 – Dobutamine Stress Echo: Increase dose stepwise; measure AVA and SVI at each stage.

Step 3 – Interpretation:

AVA >1.0 cm² with flow increase = Pseudosevere (conservative management)
AVA ≤1.0 cm² despite flow increase = Truly severe (intervention if symptomatic or EF <30%)

Step 4 – Decision: If truly severe, offer SAVR or TAVR per risk and anatomy.

Pitfall: Do not assume low gradient equals mild AS. Many patients with truly severe AS and reduced EF present with low flow and relatively low gradients. Dobutamine challenge is mandatory.

Use the Aortic Stenosis Severity Calculator to estimate severity and flow reserve.

Severe AS with Associated Coronary Artery Disease

Nearly two-thirds of patients undergoing AVR have significant CAD. Management depends on CAD complexity (SYNTAX score) and cardiac risk.

CAD Stratification

CAD Pattern	SYNTAX Score	Recommended Approach
1–2 vessel disease, proximal LAD spared	SYNTAX ≤22	TAVR alone or hybrid (TAVR + PCI)
3-vessel disease or left main	SYNTAX >22	SAVR + CABG if low-to-intermediate risk; TAVR + PCI if high risk

SYNTAX Score Use: Quantify CAD complexity to inform choice between SAVR + CABG vs TAVR + PCI. Heart Valve Team must balance CAD anatomy, AS severity, surgical risk, and patient goals.

Estimate risk with the TAVR Risk Calculator.

Severe AS with Concomitant Valve Disease

When severe AS occurs alongside significant mitral regurgitation, mitral stenosis, or tricuspid regurgitation, treatment decisions become more complex and may influence SAVR vs TAVR choice.

Common Scenarios

Concomitant Disease	SAVR Approach	TAVR Approach	Key Consideration
Severe primary MR	A: SAVR + mitral valve repair/replacement	R: TAVR leaves MR untreated	SAVR allows single-stage correction
Functional MR (secondary)	A: SAVR ± mitral repair if moderate-severe	M: TAVR may improve MR indirectly	MR often improves with AS relief
Severe MS	A: SAVR + mitral valve replacement	R: TAVR leaves MS untreated	Dual-valve surgery required
Moderate-Severe TR	A: SAVR ± tricuspid repair	M: TAVR acceptable; TR may improve	Functional TR common; may regress

Principle: For severe primary structural MR or MS, SAVR is strongly preferred as it addresses both valves in a single procedure. For functional (secondary) MR, TAVR alone may be acceptable as the primary pathology is treated and secondary lesions may improve.

Bicuspid Aortic Valve and Ascending Aorta

Bicuspid aortic valve is associated with premature AS, aortic regurgitation, and ascending aortic aneurysm. Management must address both the valve and the aorta.

Ascending Aorta Measurement & Threshold

Critical Decision Point: Ascending aorta dimension ≥4.5 cm in BAV patients warrants aortic root/ascending aorta replacement at the time of AVR, regardless of AS severity. Use CT or MRI for precise diameter measurement.

Aortic Dimension	SAVR Approach	TAVR Approach	Comments
<4.5 cm with severe AS	A: Standard AVR (mechanical or biological)	M: TAVR acceptable; aorta sizing critical	Standard aortic root diameter
≥4.5 cm with severe AS	A: Aortic root replacement (Bentall, valve-sparing root)	R: TAVR contraindicated; risk of obstruction	Aortic root/ascending aorta replacement required

DO:

Perform CT or MRI to measure ascending aorta diameter in all BAV patients
Offer aortic root replacement if diameter ≥4.5 cm and AVR indicated
Consider SAVR with possible root replacement as preferred in BAV with AS
Screen first-degree relatives for BAV and aortic aneurysm

Noncardiac Surgery in Severe Aortic Stenosis

Patients with severe AS requiring emergency or elective noncardiac surgery face heightened perioperative risk. Management depends on surgery urgency and valve symptoms.

Decision Framework

Noncardiac Surgery	AS Status	Recommended Approach
EMERGENCY (<24 hrs)	Symptomatic/asymptomatic severe AS	Proceed with surgery under tight hemodynamic monitoring; BAV + careful anesthesia
ELECTIVE, Low cardiac risk	Asymptomatic severe AS	M: Proceed with surgery if low risk; monitor intraoperatively
ELECTIVE, High risk OR Symptomatic	Severe AS	A: Consider AVR (SAVR or TAVR) preoperatively to reduce AS-related risk

Pitfall: Do not proceed with elective noncardiac surgery in a symptomatic patient with severe AS without addressing the valve. Symptom-triggered AVR preoperatively is Appropriate.

Balloon Aortic Valvuloplasty (BAV) as Bridge

BAV Indication: Emergency noncardiac surgery in symptomatic severe AS when AVR cannot be done preoperatively. BAV provides temporary hemodynamic benefit, allowing surgery under improved conditions, with planned AVR after noncardiac surgery recovery.

Failing Aortic Valve Bioprosthesis

Structural valve deterioration (SVD) of aortic bioprostheses occurs in ~50% of patients by 15 years. Management options include TAVR-in-valve, re-SAVR, and surveillance.

Treatment Options by Bioprosthesis Size and Risk

Bioprosthesis Size	Surgical Risk	TAVR-in-Valve	Re-SAVR
≥21 mm	Low-to-Intermediate	A (7)	A (8)
≥21 mm	High/Extreme	A (7)	M (5)
19–20 mm	Low-to-Intermediate	M (5)	A (8)
<19 mm	Any	R (2–3)	A (8)

TAVR-in-Valve Advantages: Avoids repeat sternotomy, shorter procedure, less blood loss, faster recovery. Suitable for most failing bioprostheses >19 mm in high-risk or elderly patients.

DO:

Monitor all aortic bioprostheses with annual echocardiography after 10 years
Intervene when hemodynamically severe with symptoms OR rapidly progressive deterioration
Offer TAVR-in-valve in high-risk patients with failing bioprosthesis ≥21 mm

Related Calculators

Use these specialized tools to support clinical decision-making in severe aortic stenosis management and risk assessment.