Diagnosis Challenges

Diagnosis Challenges

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-mortem.1 Patients ofter underreport symptoms, 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.

An accurate echocardiogram is critical to timely, lifesaving intervention for people with SAS.2-3

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 defined by ACC/AHA Guideline1

Select a stage to see the related data:

Definition

Asymptomatic severe 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
  • Mild LV hypertrophy
  • Normal LVEF

Definition

Asymptomatic severe AS with LV dysfunction

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

  • LVEF < 50%

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
  • Pulminary hypertension may be present

Definition

Symptomatic severe 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 evaluation.5

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

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.