• Clinical science
  • Clinician

Aortic valve stenosis

Summary

Aortic valve stenosis (AS) is a valvular heart disease characterized by narrowing of the aortic valve. As a result, the outflow of blood from the left ventricle into the aorta is obstructed. This leads to chronic and progressive excess load on the left ventricle and potentially left ventricular failure. The patient may remain asymptomatic for long periods of time; for this reason, AS is often detected late when it first becomes symptomatic (dyspnea on exertion, angina pectoris, or syncope). Auscultation reveals a harsh, crescendo-decrescendo murmur in systole that radiates to the carotids, and pulses are delayed with diminished carotid upstrokes. Echocardiography is the noninvasive gold standard for diagnosis. Patients with mild asymptomatic aortic stenosis are treated conservatively with monitoring and medical management of related conditions (e.g, hypertension). Symptomatic patients, or those with severe aortic valve stenosis, require immediate aortic valve replacement (AVR) as definitive treatment. Options for valve replacement include surgical AVR or transcatheter AVR (TAVR) for patients with high operative risk. Patients with severe AS have a high risk of developing acute complications such as heart failure and cardiogenic shock, which are challenging to manage and often require critical care interventions and expedited surgery or TAVR.

Epidemiology

Epidemiological data refers to the US, unless otherwise specified.

Etiology

The most common etiologies of valvular aortic stenosis include:

Pathophysiology

References:[5][6]

Clinical features

Aortic stenosis may remain asymptomatic for years; , particularly with mild or moderate stenosis. Symptoms usually start to develop when the disease progresses to severe AS, and may present at rest or on exertion.

To remember the three major symptoms of aortic valve stenosis, think: SAD (syncope, angina, dyspnea).

References:[5][7]

Classification

American Heart Association (AHA) staging system [8]

  • Used to monitor disease progression and determine the need for intervention
  • Based on echocardiographic criteria of valve anatomy and hemodynamics
AHA staging for aortic valve stenosis [8]
Stage Definition Aortic valve area (AVA) Transaortic velocity Mean aortic pressure gradient
Stage A aortic valve stenosis At risk of AS 3–4 cm2 < 2.0 m/second < 10 mm Hg
Stage B aortic valve stenosis Progressive AS Mild: 1.5–2.9 cm2 2.0– 2.9 m/second 10–19 mm Hg
Moderate: 1.0–1.4 cm2 3.0–3.9 m/second 20–39 mm Hg
Stage C1 aortic valve stenosis Asymptomatic severe AS (LVEF normal) ≤ 1.0 cm2 ≥ 4.0 m/second ≥ 40 mm Hg
Stage C2 aortic valve stenosis Asymptomatic severe AS (LVEF < 50%)
Stage D aortic valve stenosis Symptomatic severe AS

Diagnostics

Initial evaluation

Echocardiography [8]

  • Indication: Assessment of aortic valve structure, function, and stenosis severity, left ventricle and other heart valves (see valvular heart diseases)
    • TTE: recommended primary test and noninvasive gold standard used to confirm diagnosis and determine AS severity [8]
    • TEE: second-line modality for confirmation of TTE findings or operative planning [9]
  • Supportive findings
    • Calcification and narrowing of the aortic valve
    • Increased mean aortic pressure gradient and transvalvular velocity
    • Signs of cardiac remodeling, e.g., concentric hypertrophy

Other

  • Laboratory studies: usually nonspecific and therefore not routinely indicated; however, they can be useful for the evaluation of other possible etiologies.
  • ECG [2][3]
  • Chest x-ray: Used to assess for pulmonary edema or other causes of dyspnea. [2]
    • Visible calcifications within the aortic valve may indicate more severe disease. [3]
    • Narrowing of retrocardiac space (lateral view)
    • Signs of cardiac remodeling and associated heart failure: x-ray signs of LVH, pulmonary congestion, poststenotic dilation of the aorta

Additional evaluation [8]

Low-dose dobutamine stress testing

  • Indication: stage D AS with LVEF < 50% to determine the true anatomic severity of the stenosis
  • Typical findings
    • Severe AS: valve area, transaortic velocity, and mean aortic pressure gradient stay fixed.
    • Moderate AS: valve area will increase as the stroke volume increases in response to dobutamine.

Exercise stress testing

Exercise stress testing is contraindicated in patients with severe symptomatic AS (stage D).

Cardiac catheterization

Advanced imaging [8][14][15]

Consider the following noninvasive imaging options in the perioperative assessment of patients with severe AS, along with expert consultation. [8][14]

  • Cardiac CT
    • Used in select patients to rule out concomitant CAD if pretest probability is low
    • Can quantify valve calcification
    • Useful for specific measurements required prior to TAVR
  • Cardiac MRI
    • Provides precise information on anatomy and hemodynamics
    • Can be helpful in evaluating severity of AS but is not always available

Differential diagnosis

Treatment

General principles [8]

  • Aortic valve stenosis is a progressive condition and definitive management requires valve replacement.
  • Urgency of valve repair/replacement depends on staging.
    • Symptomatic and/or severe AS: aortic valve replacement usually indicated
    • Asymptomatic or mild-moderate AS: management of medical comorbidities and monitoring echocardiography; some may benefit from early valve replacement [16]
  • Management of acute complications requires individualized and specialized care.

Medical management

Management of medical comorbidities [8]

All patients should be screened and treated for other cardiac risk factors.

Management of acute complications [8][16][3][24]

Prompt critical care specialist consultation and rapid surgical referral are recommended. Patients should receive AVR as soon as possible.

Afterload reduction (e.g., with vasodilators or diuretics) in severe AS may reduce cardiac output enough to compromise systemic and myocardial perfusion. Careful titration is recommended with specialist guidance.

Severe AS compromises coronary perfusion (due to high LV pressure and low pressure in the aortic root). Avoid hypotension as it can cause cardiac ischemia.

Monitoring and prophylactic antibiotics [8]

Aortic valve replacement (AVR) and repair

Indications

  • Symptomatic patients with severe, high-gradient AS (stage D AS)
  • Asymptomatic patients with severe AS and:
    • Significantly LVEF (stage C2 AS)
    • Undergoing cardiac surgery for other indications (stage C AS or stage D AS)
  • AVR can also be beneficial for certain patients with moderate (stage B AS) to severe (stage D AS) with specific characteristics.

The presence of exertional symptoms (dyspnea on exertion, angina pectoris, syncope) is an indication for surgery.

Procedure

All patients being considered for TAVR or high-risk surgical AVR should be treated by members of a heart valve team. [8]

  • Surgical AVR
    • Recommended for patients with: [8]
  • Transcatheter AVR (TAVR)
    • Recommended for patients with high or prohibitive surgical risk and predicted survival of > 12 months [8][14]
    • Reasonable alternative for patients with intermediate surgical risk [8]
    • Emergency TAVR may be considered in certain patient groups. [28][29][30]
  • Percutaneous balloon valvuloplasty
    • Indicated in children, adolescents, and young adults without AV calcification [8]
    • Can consider as a bridging intervention in high-risk patients with stage D AS but overall benefit is questionable. [8][31]

Complications of aortic valve replacement [32][33][34]

Antithrombotic therapy after aortic valve replacement

Antithrombotic therapy for patients with prosthetic aortic valves [8][14]
Choice of agent Target INR Duration of therapy
Mechanical valve and no risk factors for thromboembolism
  • 2.5 (range 2.0–3.0)
  • Lifelong

Mechanical valve and ≥ 1 risk factor for thromboembolism

OR older generation mechanical valves

  • 3.0 (range 2.5–3.5)

Bioprosthetic valve with low risk of bleeding

  • 2.5 (range 2.0–3.0)

NOACs should be avoided in patients with mechanical valves.

Prognosis

  • Asymptomatic patients: Mortality rate is < 1% in a given year. [20]
  • Symptomatic patients: Mortality rate in the first 2 years is > 50% if left untreated. [35]
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last updated 10/07/2020
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