How should ejection fraction (EF) be assessed during an exercise stress test?

Assessment of Ejection Fraction During Exercise Stress Test

During an exercise stress test, ejection fraction (EF) should be assessed using echocardiography with image acquisition at rest, during exercise stages, at peak stress, and during recovery, with imaging of apical four-chamber, two-chamber, three-chamber, and parasternal short axis views at each stage. 1

Recommended Protocol for EF Assessment During Exercise Stress Testing

Supine Bicycle Protocol

• Rest phase:

  • Administer contrast bolus injection or infusion
  • Acquire apical four-chamber, two-chamber, three-chamber, and parasternal short axis views
  • Begin acquisition at least 20 seconds after contrast injection
  • When using infusion, pause after image acquisition

• Exercise stages (e.g., at 25 Watts):

  • Repeat contrast administration (same dosage as at rest)
  • Acquire the same views as at rest
  • Pause infusion after image acquisition if using continuous infusion

• Peak stress:

  • Administer contrast (same dosage as at rest)
  • Acquire the same views as at rest
  • Continue infusion until recovery if using continuous infusion

• Recovery phase:

  • Administer contrast bolus or continue infusion
  • Acquire the same views as at rest 1

Treadmill Protocol

• Rest phase:

  • Perform imaging with patient on imaging bed
  • Administer contrast bolus or infusion
  • Acquire standard views
  • Move patient to treadmill

• Stress phase:

  • Administer contrast at maximum effort or when termination criteria are met
  • Return patient quickly to imaging bed
  • Begin acquisition immediately
  • Acquire the same views as during rest 1

Technical Considerations for EF Assessment

1. Imaging throughout exercise:

   • For supine bicycle testing, images should be recorded from multiple views during graded exercise
   • For upright bicycle ergometer testing, have the patient lean forward over handlebars or extend arms to obtain apical images
   • Imaging should be performed throughout the test, at peak exercise, and very early in recovery 1

2. Parameters to report:

   • Blood pressure and heart rate must be reported to understand the relationship between contractile and hemodynamic responses
   • Document changes in EF from rest to stress, particularly when there is a significant decrease 2

3. Normal vs. abnormal response:

   • Normal response: augmentation of function in all LV segments and increases in LVEF and cardiac output
   • Abnormal response: new or worsening wall motion abnormality or failure to increase EF 1

Clinical Significance of EF Changes During Stress

• An EF ≤50% or a fall in EF ≥10% during stress testing indicates high risk for adverse outcomes 2
• A decrease in EF during stress testing of 5% or greater from baseline is associated with myocardial ischemia 2
• A stress-induced EF drop of 10% or greater strongly suggests severe coronary artery disease 2

Special Considerations

• When assessing patients with suspected heart failure with preserved ejection fraction (HFpEF), exercise stress echocardiography can help evaluate diastolic function 1, 3
• For patients with low LV ejection fraction and reduced cardiac output, dobutamine stress testing can be beneficial in evaluating mild aortic valve gradients 1
• Cardiac power assessment during exercise stress echocardiography provides valuable prognostic information in patients with normal EF 4

Common Pitfalls and Caveats

1. Technical challenges:

   • Ensure adequate image quality at higher heart rates during peak exercise
   • Rapid acquisition is essential after treadmill exercise as hemodynamic changes occur quickly
   • Consider using contrast agents to improve endocardial border definition

2. Interpretation considerations:

   • A decrease in LVEF with regadenoson (pharmacological) stress may not have the same clinical significance as with exercise stress 5
   • Changes in LV eccentricity during stress may provide additional information about multivessel coronary artery disease 6
   • Consider using multiple views to improve accuracy of EF assessment rather than relying on a single view 7