Aortic stenosis resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Alejandro Lemor, M.D. [2]

Synonyms and keywords: AS; critical AS; tight AS; aortic valve stenosis; calcific aortic stenosis; senile calcific aortic stenosis; degenerative calcific aortic stenosis

Aortic Stenosis Resident Survival Guide Microchapters
Overview
Causes
Diagnosis
Treatment Choice of Intervention Type of Valve and Discharge Anticoagulation Therapy
Do's
Don'ts

Overview

Aortic stenosis is the progressive narrowing of the diameter of the aortic valve (normal valve area is 3 - 4 cm²) and symptoms are caused by a decrease in stroke volume that leads to decrease perfusion to peripheral tissues, however, symptoms normally appear when the stenosis is ≤ 1.0 cm². The most common etiology of aortic stenosis is calcific aortic valve disease. The management will depend if the patient is symptomatic or asymptomatic. Surgical intervention is the treatment of choice for patients with symptomatic aortic stenosis.

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

• Infective Endocarditis

Common Causes

• Calcific aortic valve disease
• Rheumatic fever
• Congenital bicuspid aortic valve
• Endocarditis

Diagnosis

Shown below is an algorithm summarizing the diagnostic approach to aortic stenosis based on the 2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease

Abbreviations: LVH: Left ventricle hypertrophy; CXR: Chest x-ray; ECG: Electrocardiogram; LBBB: Left bundle branch block; AF: Atrial fibrillation; AVR: Aortic valve replacement; VHD: Valve heart disease; TAVR: Transcatheter aortic valve replacement; TTE: Transthoracic echocardiography

Characterize the symptoms: ❑ Most patients are asymptomatic ❑ Dyspnea on exertion ❑ Exertional dizziness ❑ Exertional angina ❑ Syncope ❑ Chest pain ❑ Palpitations

Inquire about past medical history: ❑ Previously healthy ❑ Cardiac disease: ❑ Hypertension ❑ Bicuspid aortic valve ❑ Rheumatic fever ❑ Pulmonary disease

Examine the patient: Vitals ❑ Heart rate ❑ Rhythm and rate are normal in most cases ❑ Arrhythmic (suggestive of AF in late stage disease) ❑ Blood pressure ❑ Narrow pulse pressure Respiratory rate: ❑ Normal in most cases ❑ Tachypnea (suggestive of HF) Cardiovascular ❑ Cardiac palpation ❑ Apical impulse (suggestive of LVH) ❑ Systolic thrill ❑ Pulses ❑ Pulsus parvus et tardus ❑ Pulsus bisferiens (suggestive of mixed aortic stenosis and regurgitation) ❑ Cardiac auscultation ❑ Crescendo-decrescendo systolic ejection murmur with ejection click ❑ Best heard at the upper right sternal border ❑ Bilateral radiation to the carotid arteries ❑ Murmur increases with: squatting, expiration ❑ Murmur decreases with valsalva maneuver {{#ev:youtube|MJg257pyt4I|200}} ❑ Heart sounds: ❑ Normal S1 ❑ Paradoxical splitting of S2 (not seen in early disease) ❑ S3 may be present (suggestive of LVH) Respiratory ❑ Rales (suggestive of congestive heart failure) Extremities ❑ Peripheral edema (suggestive of congestive heart failure)

Order imaging and adjuvant studies: ❑ TTE (Class I; Level of Evidence: B) Assess the following: ❑ Valve morphology ❑ Pressure gradient ❑ Aortic valve area ❑ Ejection fraction ❑ LV wall thickness and motility ❑ ECG (shows non-specific findings): ❑ LVH ❑ Left atrium enlargement ❑ LBBB ❑ AF (in late disease) ❑ CXR: ❑ Cardiomegaly ❑ Valve calcification ❑ Dilatation of ascending aorta ❑ Pulmonary congestion

Interpret results from TTE

No stenosis (Stage A) ❑ Valve area 2.5-3.5 cm² ❑ No pressure gradient

Mild to moderate stenosis (Stage B) Mild: ❑ Valve area 1.5-2.5 cm² ❑ Pressure gradient ≤ 25 mmHg Moderate: ❑ Valve area 1.0-1.5 cm² ❑ Pressure gradient 25-40 mmHg

Severe stenosis ❑ Valve area ≤ 1.0 cm² ❑ Pressure gradient ≥ 40 mmHg

❑ Normal valve ❑ Bicuspid valve ❑ Sclerotic valve

❑ Control hypertension (Class I; Level of Evidence: B) ❑ Perform a periodic echocardiogram (Class I; Level of Evidence:B) ❑ Every 3 -5 years for mild stenosis ❑ Every 1 - 2 years for moderate stenosis

Asymptomatic (Stage C)

Symptomatic (Stage D)

If patient is unstable: ❑ Administer vasodilation therapy with invasive hemodynamic monitoring (Class IIb; Level of Evidence: C)

❑ Control hypertension (Class I; Level of Evidence: B)

If patient undergoes another cardiac surgery: ❑ Schedule for AVR (Class IIa; Level of Evidence: C)

Normal LVEF (Stage C1)

LVEF < 50% (Stage C2)

High gradient (ΔP ≥ 40 mmHg) (Stage D1)

Low gradient (ΔP ≤ 40 mmHg) ❑ Normal LVEF (Stage D2) ❑ LVEF < 50% (Stage D3)

Perform a periodic echocardiogram every 6 - 12 months (Class I; Level of Evidence: B)

Schedule for AVR (Class I; Level of Evidence: A)

Schedule for AVR (Class IIa; Level of Evidence: B-C)

If aortic velocity ≥ 5 m/s or decrease in exercise tolerance: ❑ Schedule for AVR (Class IIa; Level of Evidence: B)

Choice of Intervention

Shown below is an algorithm summarizing the choice of the intervention to aortic stenosis based on the 2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease

Patient scheduled for AVR

High risk

Low to moderate risk

❑ A multidisciplinary group of physicians with expertise in VHD, cardiac imaging, interventional cardiology, cardiac anesthesia, and cardiac surgery should decide intervention (Surgical AVR or TAVR) (Class I; Level of Evidence: C) ❑ Schedule for TAVR (Class IIa; Level of Evidence: B)

❑ Schedule for surgical AVR (Class I; Level of Evidence: A)

Evaluation of Surgical and Interventional Cardiac Risk

Shown below is a table to assess the surgical and interventional risk which combines the STS risk estimate, frailty, major organ system dysfunction and procedure-specific impediments.

	Low risk	Intermediate risk	High risk	Prohibitive risk
STS PROM	<4% AND	4% to 8% OR	>8% OR	Predicted risk of death or major morbidity (all-cause) >50% at 1 year OR
Frailty*	None AND	1 index OR	≥2 indices (moderate to severe) OR	Predicted risk of death or major morbidity (all-cause) >50% at 1 year OR
Major organ system compromise not to be improved postoperatively	None AND	1 organ system OR	No more than 2 organ systems OR	≥3 organ systems OR
Procedure-specific impediment**	None	Possible procedure-specific impediment	Possible procedure-specific impediment	Severe procedure-specific impediment

STS PROM: Society of Thoracic Surgeons Predicted Risk of Mortality Score.
*Seven frailty indices: Katz Activites of Daily Living (self-sufficient in feeding, bathing, dressing, transferring, toileting and urinary continence) and self-sufficient in deambulation (no walking aid or assist required or 5-meter walk in <6 s).
**Procedure-specific impediment examples: tracheostomy present, heavily calcified ascending aorta, chest malformation, arterial coronary graft adherent to posterior chest wall or radiation damage.

Type of Valve and Discharge Anticoagulation Therapy

❑ Determine the age of the patient ❑ Check for contraindications for anticoagulation

❑ Patients ≤ 70 years old (Class IIa; Level of Evidence: B), and ❑ No contraindication for anticoagulation

❑ Patients ≥ 70 years old (Class IIa; Level of Evidence: B), or ❑ Patients with anticoagulant therapy contraindications (Class I; Level of Evidence: C)

Mechanical Prosthesis

Bioprosthesis

Patient with risk factors

Patient without risk factors

AVR

TAVR

❑ Give warfarin to achieve INR of 3.0 ❑ Give aspirin 75-100 mg/d Both long term

❑ Give warfarin to achieve INR of 2.5 ❑ Give aspirin 75-100 mg/d Both long term

❑ Give warfarin to achieve INR of 2.5 for 3 months ❑ Then give aspirin 75-100 mg/d long term

❑ Give clopidogrel 75 mg/d ❑ Give aspirin 75-100 mg/d Both for 6 months

❑ Either a bioprosthetic or mechanical valve is reasonable in patients between 60 and 70 years of age. (Class IIa; Level of Evidence: B).

Do's

❑ Give ACE inhibitors to control hypertension in patients with asymptomatic aortic stenosis.
❑ Exercise testing in asymptomatic patients with AS may be considered to elicit exercise-induced symptoms and abnormal blood pressure responses (Class IIb; Level of Evidence: B).
❑ Dobutamine stress echocardiography is reasonable to evaluate patients with low-flow/low-gradient AS and LV dysfunction (Stage D3) (Class IIa; Level of Evidence: B)
❑ Aortic balloon valvotomy might be reasonable as a bridge to surgery in hemodynamically unstable adult patients with AS who are at high risk for AVR or cannot be performed because of serious comorbid conditions.(Class IIb; Level of Evidence: C).

Don'ts

❑ Do not perform a stress test in a symptomatic patient with stage D aortic stenosis (Class III; Level of Evidence: B).
❑ Do not give statins to prevent hemodynamic progression in patients with mild to moderate calcific aortic valve disease (Class III; Level of Evidence: A).
❑ TAVR is not recommended in patients in whom existing comorbidities would preclude the expected benefit from correction of AS (Class III; Level of Evidence: B)
❑ Do not give vasodilators to patients with severe AS as they may cause severe hypotension.
❑ Endocarditis prophylaxis is not indicated in patients with AS.

References

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