What is a normal ejection fraction and what ejection fraction values are considered pathologic?

Normal and Pathologic Ejection Fraction Values

A normal ejection fraction is ≥50%, and an EF ≤40% is definitively pathologic, defining heart failure with reduced ejection fraction (HFrEF). 1

Classification Framework

The 2022 AHA/ACC/HFSA guidelines provide the authoritative classification system for EF 1:

Normal EF: ≥50%

• This represents preserved systolic function
• Patients with heart failure symptoms and EF ≥50% are classified as HFpEF (heart failure with preserved ejection fraction)

Mildly Reduced EF (HFmrEF): 41-49%

• This intermediate range represents a dynamic state
• Patients typically are either improving from HFrEF or deteriorating toward it
• One measurement is insufficient - you must track the trajectory over time
• These patients require additional objective evidence of cardiac dysfunction (elevated natriuretic peptides, evidence of increased LV filling pressures) to confirm heart failure diagnosis

Reduced EF (HFrEF): ≤40%

• This is definitively pathologic
• Most randomized controlled trials demonstrating survival benefit enrolled patients with EF ≤35% or ≤40%
• This threshold triggers guideline-directed medical therapy with proven mortality benefit

Refined Understanding from Population Data

Recent meta-analysis data provides more granular normal ranges 2:

• Lower limit of normal: approximately 52% for men and 53% for women
• Mean normal EF: 62.8% overall (61.9% men, 63.7% women)
• Critical threshold: An EF <50% has <5% probability of being within normal range across all demographic groups
• Asian populations show 2-3 percentage points higher values

Clinical implication: While guidelines use ≥50% as the HFpEF threshold, population data suggests that EF values of 50-52% in men or 50-53% in women warrant close monitoring, as they fall at the extreme lower boundary of normal.

Prognostic Significance

The "low-normal" range (50-55%) carries clinical importance 3:

• Asymptomatic individuals with EF 50-54% have 3.6-fold increased risk of developing heart failure over 10 years compared to those with EF ≥55%
• This risk is lower than those with EF <50% (9.5-fold increased risk) but still clinically significant
• However, low-normal EF does not increase mortality risk in asymptomatic patients

Common Pitfalls to Avoid

1. Don't rely on single measurements in the 41-49% range - serial assessments are essential to determine trajectory
2. Don't dismiss EF of 50-54% as completely normal - these patients need cardiovascular risk factor optimization and monitoring
3. Don't assume normal EF excludes heart failure - HFpEF represents at least 50% of heart failure cases and is increasing in prevalence 1
4. Don't forget that EF can vary by measurement technique - ensure consistency in follow-up assessments

Sex and Age Considerations

• Women have slightly higher normal EF values (approximately 2% higher than men) 2
• Age does not significantly affect normal EF ranges in most studies
• Women with heart failure are more likely to have preserved EF than men 4