Aortic stenosis surgery indications

Aortic stenosis surgery
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Mohammed A. Sbeih, M.D. [2]; Usama Talib, BSc, MD [3]

Overview

Aortic stenosis requires aortic valve replacement if medical management does not successfully control symptoms. According to a prospective, single-center, nonrandomized study of 25 patients, percutaneous implantation of an aortic valve prosthesis in high risk patients with aortic stenosis results in marked hemodynamic and clinical improvement when successfully completed.

Indications

• in symptomatic patients with severe high-gradient AS (Stage D1), AVR has beneficial effects on survival, symptoms, and LV systolic function.
• The most common initial symptom of AS is exertional dyspnea or decreased exercise tolerance.
• More severe classical symptoms of AS, including HF, syncope, or angina, can be avoided by appropriate treatment at the onset of even mild symptoms.
• Outcomes after surgical or transcatheter AVR are excellent.
• Improvement in exercise tolerance has been shown by exercise test after AVR.
• In asymptomatic patients with severe AS and normal LV systolic function, the survival rate during the asymptomatic phase is similar to that of age-matched controls, with a low risk of sudden death (<1% per year). However, in patients with a low LVEF and severe AS, survival is better in those who undergo AVR than in those treated medically.
• Disease progression occurs in nearly all patients with severe asymptomatic AS. Initiation of symptoms within 2 to 5 years is likely when aortic velocity is ≥4.0 m/s or mean pressure gradient is ≥40 mm Hg.

• Mean pressure gradient is a strong predictor of outcome after AVR, with better outcomes seen in patients with higher gradients.
• Outcomes are poor with severe low-gradient AS but are still better with AVR than with medical therapy in those with a low LVEF, especially in the presence of contractile reserve.
• Severe AS on dobutamine stress testing is defined when a maximum velocity >4.0 m/s with a valve area ≤1.0 cm2 at any point during the test protocol, with a maximum dobutamine dose of 20 mcg/kg per minute.
• Out come in patients without contractil reserve is poor with either surgical or medical therapy.
• LVEF typically increases by 10 LVEF units and may return to normal if afterload mismatch was the cause of LV systolic dysfunction.
• Low-flow, low-gradient severe AS with preserved LVEF should be considered in patients with a severely calcified aortic valve, an aortic velocity <4.0 m/s (mean pressure gradient <40 mm Hg), and a valve area ≤1.0 cm2, stroke volume index <35 mL/m2, small LV cavity with thick walls, diastolic dysfunction, and a normal LVEF (≥50%).
• If hypertension is present, blood pressure should is controlled before reevaluation of AS severity.
• Valve area is indexed to body size because an apparent small valve area may be only moderate AS in a small patient.
• An aortic valve area index ≤0.6 cm2/m2 suggests severe AS.
• Transaortic [[stroke volume] is calculated by [[Doppler] or 2D imaging.
• Exercise testing may be helpful in clarifying symptom status in patients with severe AS including a fall of ≥10 mm Hg in systolic blood pressure from baseline to peak exercise or a significant decrease in exercise tolerance as compared with age and sex normal standards.
• In patients with very severe AS and an aortic velocity ≥5.0 m/s or mean pressure gradient ≥60 mm Hg, the rate of symptom onset is approximately 50% at 2 years. *Early surgery in patients with aortic velocity ≥4.5 m/sa showed significant survival benefit.
• An elevated serum [[BNP] level is a marker of subclinical HF and LV decompensation in [[severe] AS.
• In asymptomatic patients with AS with the aortic velocity reaches ≥2 m/s, hemodynamic progression leading to symptom .
• Hemodynamic progression occurs when aortic velocity increases about 0.3 m/s per year, an increase in the mean gradient of 7 to 8 mm Hg per year, and a decrease in valve area of 0.15 cm2 per year.
• Predictors of rapid disease progression include older age, more severe valve calcification, and a faster rate of hemodynamic progression in serial studies.
• Elective AVR may be considered In patients with an aortic velocity >4 m/s, and the presence of predictors of rapid disease progression.
• In adults with initially asymptomatic severe AS, the rate of sudden death is low (<1% per year). However, an aortic velocity ≥5 m/s or an LVEF <60% is associated with higher all-cause and cardiovascular mortality rates in the absence of AVR.
• A progressive decrease in LVEF is most likely in those with an LVEF <60% before AS becomes severe.
• Hemodynamic progression eventually leading to symptom onset occurs in nearly all asymptomatic patients with AS.

. The rate of symptom onset is strongly dependent on the severity of AS.

• Patients with asymptomatic AS require periodic monitoring for the development of symptoms and progressive disease.

Recommendations for intervention in aortic stenosis

Symptomatic aortic stenosis:

(Class I, Level of Evidence B):

❑ Intervention is considered in symptomatic patients with severe, high-gradient aortic stenosis mean gradient ≥ 40 mmHg, peak velocity ≥ 4.0 m/s, and valve area ≤ 1.0 cm2 (or ≤ 0.6 cm2/m2) ❑ntervention is considered in symptomatic patients with severe low-flow (SVi ≤35 mL/m2), low-gradient (<40 mmHg) aortic stenosis with reduced ejection fraction (<50%), and evidence of flow (contractile) reserve

(Class IIa, Level of Evidence C):

❑ Intervention is recommended in symptomatic severe AS with low-flow, low-gradient (<40 mmHg) aortic stenosis with normal ejection fraction ❑ Intervention is recommended in symptomatic patients with low-flow, low-gradient severe aortic stenosis and reduced ejection fraction without flow (contractile) reserve, severe aortic stenosis proven by CCT calcium score

(Class III, Level of Evidence C) :

❑ Intervention is not recommended in patients with severe comorbidities when the intervention is unlikely to improve quality of life or prolong survival >1 year

Asymptomatic severe aortic stenosis :

(Class I, Level of Evidence B):

❑ Intervention is recommended in asymptomatic patients with severe aortic stenosis and systolic LV dysfunction (LVEF < 50%) without another cause

(Class I, Level of Evidence C):

❑ Intervention is recommended in asymptomatic patients with severe aortic stenosis, symptomtomatic on exercise testing

(Class IIa, Level of Evidence B):

❑ Intervention should be considered in asymptomatic patients with severe aortic stenosis and systolic LV dysfunction (LVEF <55%) without another cause

(Class IIa, Level of Evidence C):

❑ Interventin is recommended in asymptomatic patients with severe aortic stenosis and a sustained fall inblood pressure (>20 mmHg) during exercise testing

(Class IIa, Level of Evidence B):

❑Intervention is considered in asymptomatic patients with LVEF >55% and a normal exercise test if the procedural risk is low and in the presence of one of the following: Very severe aortic stenosis (mean gradient ≥60 mmHg or Vmax > 5 m/s Severe valve calcification ( assessed by CCT) and Vmax progression ≥0.3 m/s/year Elevated BNP levels (>3× age- and sex-corrected normal range) confirmed by repeated measurements and without other causes

Type of intervention:

(Class I, Level of Evidence C):

❑Aortic valve interventions should be performed in an experienced center

(Class I, Level of Evidence B):

❑SAVR is recommended in younger patients who are low risk for surgery (<75 yearse and STS PROM/EuroSCORE II <4%), or in patients who are operable and unsuitable for transfemoral TAVI ❑SAVR or TAVI are recommended for patients based on clinical, anatomical, and procedural characteristics

(Class I, Level of Evidence A):

❑TAVI is recommended in older patients (≥75 years), or in those who are high risk (STS PROM/EuroSCORE IIf>8%) or unsuitable for surgery

(Class IIb, Level of Evidence C):

❑ Non-transfemoral TAVI may be considered in patients who are inoperable and unsuitable for transfemoral TAVI ❑Balloon aortic valvotomy may be considered as a bridge to SAVR or TAVI in hemodynamically unstable patients and (if feasible) in those with severe aortic stenosis who require urgent high risk non-cardiac surgery

Abbreviations: BNP: B-type natriuretic peptide; CABG: Coronary artery bypass grafting; LV: Left ventricle; LVEF:Left ventricular ejection fraction ; CCT:Cardiac computed tomography; SAVR: Surgical aortic valve replacement; STS-PROM: Society of Thoracic Surgeons - predicted risk of mortality; SVi: Stroke volume index; TAVI:Transcatheter aortic valve implantation ; Vmax:Peak transvalvular velocity

The above table adopted from 2021 ESC Guideline

Valvular AS Assessment of velocity, gradient

Low-gradient AS Vmax < 4 m/s ΔPm < 40 mmHg

High-gradient AS Vmax ≥ 4 m/s, ΔPm ≥ 40 mmHg

AVA ≤ 1.0 cm2

High flow status

Yes Determination of flow status

NO Moderate AS

Yes Assessment of normal flow condition

NO Severe AS

Normal flow SVi > 35 mL/m2

Low flow SVi ≤ 35 mL/m2

Severe AS unlikely

LVEF ≥ 50%

NO DSE flow reservec

Yes CCT to assess AV calcification

NO, CCT to assess AV calcification

Yes, AVA ≤ 1.0 cm2

Yes Severe AS

NO Pseudo-severe AS

Abbreviations: AS: Aortic stenosis; AV: Aortic valve; AVA: Aortic valve area; LVEF: Left ventricular ejection fraction ; CT: Computed tomography; △Pm: Mean pressure gradient; DSE: Dobutamine stress echocardiography; LV: Left ventricular; SVi: Stroke volume index; Vmax: Peak transvalvular velocity

The above table adopted from 2021 ESC Guideline

• High flow is reversible in conditions such as anemia, hyperthyroidism orarterio-venous fistula and may also be present in patients with hypertrophic obstructive cardiomyopathy.
• The definition of Normal flow by pulsed Doppler echocardiography is  :

  Cardiac index 4.1 L/min/m2 in men and women

  SVi 54 mL/m2 in men, 51 mL/m2 in women

• DSE flow reserve is defined as > 20% increase in stroke volume in response to low-dose dobutamine.
• Pseudo-severe aortic stenosis is defined as AVA >1.0 cm2 with increased flow.
• CT measurement of aortic valve calcification (Agatston units) for definition of high likely severe AS:

  men >3000, women>1600

  Likely: men >2000, women >1200

  Unlikely: men <1600, women <800

Shown below is an algorithm summarizing the management of symptomatic and asymptomatic patients with aortic stenosis and the indications for AVR. If the patient does not meet any of the decision pathways in the algorithm, regular monitoring is recommended and AVR is not indicated.

Abbreviations: AVR: Aortic valve replacement; LVEF: Left ventricular ejection fraction; ΔP_mean: mean pressure gradient; V_max: maximum velocity

Abnormal aortic valve AND Reduction in systolic opening

Severe aortic stenosis: Vmax≥4m/s AND ΔPmean≥40 mmHg

Vmax3-3.9 m/s AND ΔPmean20-39 mmHg

Is the patient symptomatic?

Is the patient symptomatic?

Yes (Stage D1)

No (Stage C)

Yes

No (Stage B)

LVEF <50% (Stage C2)

Is LVEF <50%?

The patient is undergoing another cardiac surgery

The patient is undergoing another cardiac surgery

Yes

No

Vmax≥5m/s AND ΔPmean≥60 mmHg (Very severe stage C1) AND Low surgical risk

Dobutamine stress echocardiography: Aortic valve area ≤1 cm2 AND Vmax≥4 ms (Stage D2)

Aortic valve area ≤1 cm2 AND LVEF ≥50% (Stage D3)

Abnormal exercise treadmill test

The symptoms are likely the result of the aortic stenosis

ΔVmax>0.3 m/s/y AND Low surgical risk

AVR (Class I)

AVR (Class IIa)

AVR (Class IIb)

AVR (Class IIa)

AVR (Class IIa)

AVR (Class IIa)

Shown below is an algorithm summarizing the approach to patients with low flow, low gradient aortic stenosis.

Abbreviations: AVR: Aortic valve replacement; EOA: Effective orifice area; ΔP_mean: mean pressure gradient

Ultrasound evaluation of aortic stenosis Effective orifice area (EOA)≤ 1 cm2 Pressure gradient (ΔP)<40 mmHg

Low grade low flow aortic stenosis

Normal left ventricular ejection fraction

Left ventricular ejection fraction≤ 40-50%

No specific recommendations: - Surgical AVR, or - Transcather AVR, or - Medical treatment

Dobutamine stress test

Increase in stroke volume by ≥ 20%

Increase in stroke volume by <20%

Presence of left ventricular flow reserve

Absence of left ventricular flow reserve

ΔP≥40 EOA<1-1.2

ΔP<40 EOA≥1-1.2

EOA<1-1.2

True severe aortic stenosis

Pseudo-severe aortic stenosis

True severe aortic stenosis

Surgical AVR with/without CABG

Medical treatment Close follow up

Transcather AVR

Aortic valve replacement is indicated in the following situations:

• If the patient has symptoms due to aortic stenosis, such as angina, dizziness, syncope, dyspnea or heart failure symptoms . Average survival after the onset of these symptoms is around two to three years . With the presence of symptoms; the patient may be at risk for sudden death .
• Severe aortic stenosis (valve area < 1.0 cm², or the aortic jet velocity is over 4.0 m/sec and the mean transvalvular gradient exceeds 40 mm Hg) if the patient has symptoms, left ventricular dysfunction (ejection fraction < 50%) or undergoing coronary artery bypass grafting. Valve replacement should not be performed for isolated severe AS in asymptomatic patients.
• Usually performed in patients with moderate AS with symptoms to improve symptoms and prolong life expectancy, or if the patient undergoing coronary artery bypass grafting or aortic root reconstruction surgery.

If there are no contraindications to anticoagulants, mechanical prostheses are preferred in patients < 65 years of age. If the patient > 65 years or has any contraindication to anticoagulants; then bioprosetheses are preferred (biologic valve).

Age is not a contraindication to aortic valve replacement in aortic stenosis.

Low Flow Aortic Stenosis

If there is a decline in left ventricular function due to systolic dysfunction, there may be only a moderate transvalvular gradient or low flow aortic stenosis. If there is fibrosis of the left ventricle, there may be incomplete recovery after aortic valve replacement. This scenario can also occur among patients in whom there is a history of myocardial infarction; there is insufficient contractility to mount an aortic gradient.

Definition

1. An aortic valve areas < 1.0 cm²
2. A left ventricular ejection fraction < 40%
3. A mean pressure difference or gradient across the aortic valve of < 30 mm Hg

With a dobutamine infusion, the aortic valve area should increase to > 1.2 cm², and the mean pressure gradient should rise above 30 mm Hg. If there is a failure to acheive these improvements, early surgical mortality is 32–33%, but it is only 5–7% in those patients who can augment their contractility and gradient. Survival at five years was 88% after surgery if the patient can augment their contractility, but only 10–25% if the patient cannot augment their contractility.

It should be noted that left ventricular contractile reserve is a better predictor of surgical outcomes than markers of stenosis. Aortic valve surgery is indicated if there is severe AS along with an increase in the systolic velocity integral by >20% during a dobutamine infusion.

2008 Focused Update Incorporated Into the 2006 ACC/AHA Guidelines for the Management of Patients with Valvular Heart Disease (DO NOT EDIT)

Aortic Valve Replacement Indications (DO NOT EDIT)

Class I

"1. AVR is indicated for symptomatic patients with severe AS. (Level of Evidence: B)"

"2. AVR is indicated for patients with severe AS undergoing coronary artery bypass graft surgery (CABG). (Level of Evidence: C)"

"3. AVR is indicated for patients with severe AS undergoing surgery on the aorta or other heart valves. (Level of Evidence: C)"

"4. Aortic valve replacement is indicated for patients with severe AS and LV dysfunction (LV ejection fraction less than 50%). (Level of Evidence: C)"

"5. In patients with bicuspid valves undergoing AVR because of severe AS or AR, repair of the aortic root or replacement of the ascending aorta is indicated if the diameter of the aortic root or ascending aorta is greater than 4.5 cm. (Level of Evidence: C)"

Class III

"1. AVR is not useful for the prevention of sudden death in asymptomatic patients with AS who have none of the findings listed under the Class IIa/IIb recommendations(Level of Evidence: B)"

Class IIa

"1. AVR is reasonable for patients with moderate AS undergoing CABG or surgery on the aorta or other heart valves. (Level of Evidence: B)"

Class IIb

"1. AVR may be considered for asymptomatic patients with severe AS and abnormal response to exercise (e.g., development of symptoms or asymptomatic hypotension). (Level of Evidence: C)"

"2. AVR may be considered for adults with severe asymptomatic AS if there is a high likelihood of rapid progression (age, calcification, and CAD) or if surgery might be delayed at the time of symptom onset. (Level of Evidence: C)"

"3. AVR may be considered in patients undergoing CABG who have mild AS when there is evidence, such as moderate to severe valve calcification, that progression may be rapid. (Level of Evidence: C)"

"4. AVR may be considered for asymptomatic patients with extremely severe AS (aortic valve area less than 0.6 cm2, mean gradient greater than 60 mm Hg, and jet velocity greater than 5.0 m per second) when the patient's expected operative mortality is 1.0% or less. (Level of Evidence: C)"