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]

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, however, symptoms normally appear when the stenosis is ≤ 1.0 cm².

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

Management

Shown below is an algorithm summarizing the approach to aortic stenosis

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

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: ❑ Heart rate ❑ Pulses ❑ Pulsus parvus et tardus ❑ Cardiac palpation ❑ Apical impulse (due to LVH) ❑ Systolic thrill ❑ 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}} ❑ Pulmonary auscultation: search for rales (seen when congestive heart failure has developed)

Order imaging and adjuvant studies: ❑ Order an echocardiography, assess: ❑ Valve morphology ❑ Pressure gradient ❑ Aortic valve area ❑ Ejection fraction ❑ LV wall thickness and motility ❑ Order a CXR, look for: ❑ Cardiomegaly ❑ Valve calcification ❑ Dilatation of ascending aorta ❑ Pulmonary congestion ❑ Order a ECG, look for: ❑ LVH ❑ Left atrium enlargement ❑ LBBB ❑ AF (in late disease)

Interpret results from echo

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

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

Patient asymptomatic (Stage C)

Patient symptomatic (Stage D)

❑ 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
STS: Society of Thoracic Surgeons

Patient scheduled for AVR

High risk ❑ STS Score > 10 ❑ EuroScore > 20

Low to moderate risk ❑ STS Score < 10 ❑ EuroScore < 20

❑ 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)

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 AR.

References

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