What does it mean to have a preserved ejection fraction?

Understanding Preserved Ejection Fraction in Heart Failure

Preserved ejection fraction refers to a left ventricular ejection fraction (LVEF) of 50% or greater in patients with heart failure, a condition known as heart failure with preserved ejection fraction (HFpEF).

Definition and Classification

Heart failure with preserved ejection fraction (HFpEF) is defined as:

• Clinical syndrome with symptoms and/or signs of heart failure
• Left ventricular ejection fraction (LVEF) ≥50%
• Evidence of structural and/or functional cardiac abnormalities
• Objective evidence of elevated filling pressures or congestion 1

The American College of Cardiology/American Heart Association guidelines classify heart failure based on ejection fraction into three categories:

• HFrEF (Heart Failure with reduced Ejection Fraction): LVEF ≤40%
• HFmrEF (Heart Failure with mildly reduced Ejection Fraction): LVEF 41-49%
• HFpEF (Heart Failure with preserved Ejection Fraction): LVEF ≥50% 1

Pathophysiology and Characteristics

HFpEF is characterized by:

• Normal or near-normal left ventricular ejection fraction (≥50%)
• Diastolic dysfunction (impaired relaxation and/or filling)
• Increased left ventricular filling pressures
• Concentric remodeling rather than dilation of the left ventricle
• Preserved stroke volume at rest but inability to increase stroke volume during exercise 1, 2

Diagnostic Criteria

The Universal Definition of Heart Failure requires:

1. Symptoms and/or signs of heart failure (dyspnea, fatigue, ankle swelling, pulmonary rales, elevated jugular venous pressure)
2. Caused by structural/functional cardiac abnormalities
3. At least one of the following:
   • Elevated natriuretic peptides (BNP >35 pg/mL or NT-proBNP >125 pg/mL for ambulatory patients)
   • Objective evidence of cardiogenic pulmonary or systemic congestion 1

For HFpEF specifically:

• LVEF ≥50%
• Evidence of diastolic dysfunction
• Elevated filling pressures at rest or with exertion 1, 3

Clinical Significance

HFpEF represents approximately 50% of all heart failure cases and is:

• More common in older adults
• More prevalent in women than men
• Associated with comorbidities such as hypertension, diabetes, obesity, and atrial fibrillation
• Characterized by exercise intolerance and dyspnea on exertion
• Associated with significant morbidity, frequent hospitalizations, and mortality rates similar to HFrEF 1, 3

Diagnostic Challenges

Diagnosing HFpEF can be challenging because:

• Symptoms may be nonspecific and overlap with other conditions
• Natriuretic peptide levels may be lower than in HFrEF (especially in obesity)
• Diastolic dysfunction may only be evident during exercise
• Need to exclude other causes of symptoms with preserved EF (valvular disease, infiltrative disease, pericardial disease) 1, 3

Treatment Approaches

Unlike HFrEF, treatment options for HFpEF have historically been limited. Current approaches include:

• SGLT2 inhibitors (dapagliflozin, empagliflozin) which have shown to reduce HF hospitalizations
• Diuretics for symptom relief in patients with congestion
• Exercise training and weight loss for patients with obesity
• Management of comorbidities (hypertension, diabetes, atrial fibrillation)
• Heart failure self-care education 3, 4

Key Differences from HFrEF

• Different underlying pathophysiology (diastolic dysfunction vs. systolic dysfunction)
• Different ventricular remodeling patterns (concentric vs. eccentric)
• Many treatments proven effective for HFrEF have not shown similar benefits in HFpEF
• Different patient demographics (more women, older age in HFpEF) 2, 5

Understanding preserved ejection fraction is crucial for appropriate diagnosis and management of this increasingly prevalent form of heart failure, which carries significant morbidity and mortality despite the "preserved" pump function.