Ejection fraction (EF)

Left ventricular ejection fraction is usually determined by echocardiography or radiographic ventriculography.

The ejection fraction is:

stroke volume = (end diastolic volume - end systolic volume)

ejection fraction = stroke volume / end diastolic volume

The ejection fraction is a good predictor of longevity in patients with heart failure but does not correlate with symptomatic limitation.

Systolic dysfunction

• LV (left ventricular) systolic dysfunction is assessed using the EF (ejection fraction) (the percentage of the end diastolic volume ejected during systole)
  • in most cases, this is estimated by eye from all the available echo views
  • normal ejection fraction is 50%-80%, but values as low as 5% are compatible with life (end-stage heart failure)
    
    
  • what is an abnormal left ventricular ejection fraction?
    • current ACCF/AHA guidelines classify patients with a left ventricular ejection fraction (LVEF) of >=50% as having a preserved ejection fraction (1), and previous studies have found that asymptomatic patients with lower LVEF are at greater risk of developing HF
      • in a study of patients with untreated hypertension, an LVEF of <50% was associated with a 10-fold increased risk of incident HF, compared with patients with an LVEF of >50% (2)
      • the MESA (Multi-Ethnic Study of Atherosclerosis) study, an LVEF of <50% was associated with a 12-fold increased risk of HF and 3.5-fold increased risk of all-cause mortality (3)
        
        
  • classifications of heart failure using LVEF
    • Heart failure definition
      • Heart Failure with
        • Reduced ejection fraction (HFrEF) - LVEF<40%
          
          
        • Mid-range ejection fraction (HFmEF) - LVEF 40- 49%
          
          
        • Preserved ejection fraction (HFpEF) - LVEF>=50%
          
          
    • Heart failure definition
      • Systolic impairment and EF
        • Severe reduction - EF <35%
          
          
        • Moderate reduction - EF 35-39%
          
          
        • Mild reduction- 40-49%
          
          
        • Normal-EF>=50%

Diastolic dysfunction

• if there is a normal LV ejection fraction in the presence of the heart failure syndrome leads to consideration of a diagnosis of diastolic dysfunction
• in diastolic dysfunction typical echo findings in diastolic dysfunction are normal LV cavity size, thickened ventricle, and reversed E/A ratio

The E/A ratio

• when flow across the MV is assessed with PW Doppler, two waves are characteristically seen
  • represent passive filling of the ventricle (early [E] wave)
  • active filling with atrial systole (atrial [A] wave)
    
    
  • classically, the E-wave velocity is slightly greater than that of the A wave
    • however, in conditions that limit the compliance of the LV, two abnormalities are possible:
      • reversal
        • the A wave is greater than the E wave
        • indicates slow filling caused by older age, hypertension, left ventricular hypertrophy (LVH), or diastolic dysfunction
      • exaggeration of normal
        • a tall, thin E wave with a small or absent A wave
        • indicates restrictive cardiomyopathy, constrictive pericarditis, or infiltrative cardiac disease (eg, amyloidosis)

Reference:

• Yancy CW, et al. 2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines J Am Coll Cardiol 2013; 62: e147-e239
• Verdecchia P et al.i Asymptomatic left ventricular systolic dysfunction in essential hypertension: prevalence, determinants, and prognostic value Hypertension 2005; 45:412-418
• Yeboah J et al. Prognosis of individuals with asymptomatic left ventricular systolic dysfunction in the Multi-Ethnic Study of Atherosclerosis (MESA) Circulation 2012;126:2713-2719
• Walsh J. Nottinghamshire Heart Failure Traffic Light Guidelines. Nottingham University Hospitals NHS Trust (Accessed May 19th 2018)