Diagnosis Challenges

Diagnosis Challenges

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Optimal imaging is crucial to determine timing of intervention for severe AS which, once symptomatic, is critical for survival

The detection of severe aortic stenosis (SAS) may be missed in up to 50% of SAS cases until post-mortem1. Symptom onset may be subtle and overlooked by the patient, so relying on an echocardiogram is critical to determine disease progression. The ACC Guideline recommends a comprehensive transthoracic echocardiogram (TTE) be performed for known or suspected valve disease. And regular follow-up with TTE should be performed at least yearly to evaluate a patient’s symptoms and disease progression once advanced to SAS.

An accurate and timely diagnosis is critical for people with symptomatic SAS2-3.

Severe aortic stenosis can pose unique challenges that require special considerations during work-up and imaging

Considering hemodynamic parameters is essential for accurate evaluations and timely aortic valve replacement.

Hemodynamic parameters for symptomatic severe AS defined by ACC/AHA Guideline1

Select a stage to see the related data:

Definition

Symptomatic severe high gradient AS

Valve hemodynamics

Aortic valve areas:
Typically AVA ≤ 1.0 cm2
(or AVAi ≤ 0.6 cm2/m2)
Aortic Vmax:
≥ 4 m/s
or
Mean pressure gradient:
≥ 40 mm Hg

Hemodynamic consequences

  • LV diastolic dysfunction
  • LV hypertrophy
  • Pulmonary hypertension may be present

Definition

Symptomatic severe AS low-flow/low-gradient with reduced LVEF

Valve hemodynamics

Aortic valve areas:
AVA ≤ 1.0 cm2
Aortic Vmax:
< 4 m/s
or
Mean pressure gradient:
< 40 mm Hg

Hemodynamic consequences

  • LV diastolic dysfunction
  • LV hypertrophy
  • LVEF < 50%

Definition

Symptomatic severe low-gradient with normal LVEF or paradoxical low-flow

Valve hemodynamics

Aortic valve areas:
AVA ≤ 1.0 cm2
(AVAi ≤ 0.6 cm2/m2)
and stroke volume index < 35 ml/m2 measured when patient is normotensive*
Aortic Vmax:
< 4 m/s
or
Mean pressure gradient:
< 40 mm Hg

*Systolic blood pressure < 140 mm Hg.

Hemodynamic consequences

  • Increased LV relative wall thickness
  • Small LV chamber with low stroke volume
  • Restrictive diastolic filling
  • LVEF ≥ 50%

As many as 35% of SAS patients may be in a low-flow state (SVi<35 ml/m2) and require careful hemodynamic evaluation5.

Avoid the underestimation of LVOT area and thus underestimation of flow rate2

Patients with lower than expected gradients despite preserved LVEF can lead to an underestimation of severity, which may delay aortic valve replacement6

Use baseline and low-dose dobutamine stress echocardiography to differentiate between true and pseudo SAS in those with reduced LVEF4

The progression of severity of disease can be underestimated

Download the following echocardiographic guide for a review of common challenges and special considerations specific to severe aortic stenosis.

Empower your team with advanced echo techniques that can lead to a treatment evaluation of severe aortic stenosis.

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Recommended resources

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Echo Quick Reference Guide

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References:   1. Das P, et al. The patient with a systolic murmur: severe aortic stenosis may be missed during cardiovascular examination. Q J MedJ 2000;93:685-688. 2. Baumgartner, H. (2017). Recommendations on the Echocardiographic Assessment of Aortic Valve Stenosis: A Focused Update from the European Association of Cardiovascular Imaging and American Society of Echocardiography. JASE, 30:372-92. 3. Malaisrie, C. (2014). Mortality While Waiting for Aortic Valve Replacement. Ann Thorac Surg 98:1564-71. 4. Nishimura RA, Otto CM, Bonow RO, et al. 2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2014;129(23):2440-92. 5. Clavel MA, Magne J, Pibarot P. Low gradient aortic stenosis. Eur Heart J. 2016; 37(34): 2645–2657. 6. Dumesnil, J. G. (2009). Paradoxical low flow and/or low gradient severe aortic stenosis despite preserved left ventricular ejection fraction. EHJ, 31(3), 281–289.