What are the primary types of heart failure?

Types of Heart Failure

Heart failure is classified into three main types based on left ventricular ejection fraction (LVEF): heart failure with reduced ejection fraction (HFrEF) with LVEF ≤40%, heart failure with mildly reduced ejection fraction (HFmrEF) with LVEF 41-49%, and heart failure with preserved ejection fraction (HFpEF) with LVEF ≥50%. 1

Classification Based on Ejection Fraction

1. Heart Failure with Reduced Ejection Fraction (HFrEF)

• Definition: LVEF ≤40%
• Characteristics:
  • Systolic dysfunction with impaired contractility
  • Often associated with coronary artery disease and prior myocardial infarction
  • Ventricular dilation and adverse cardiac remodeling
  • More responsive to established neurohormonal therapies (beta-blockers, ACE inhibitors, etc.)

2. Heart Failure with Mildly Reduced Ejection Fraction (HFmrEF)

• Definition: LVEF 41-49%
• Characteristics:
  • Primarily mild systolic dysfunction
  • Features of diastolic dysfunction
  • Represents a "grey area" between HFrEF and HFpEF
  • May progress to HFrEF or improve to HFpEF 1

3. Heart Failure with Preserved Ejection Fraction (HFpEF)

• Definition: LVEF ≥50%
• Characteristics:
  • Diastolic dysfunction with impaired ventricular filling
  • Often associated with hypertension, obesity, diabetes, and aging
  • Abnormal cardiac relaxation and increased stiffness
  • Less responsive to traditional HF therapies 1, 2

4. Heart Failure with Improved Ejection Fraction (HFimpEF)

• Definition: Baseline LVEF ≤40%, with ≥10-point increase from baseline and second measurement >40%
• Represents patients who have recovered function after treatment 3

Classification Based on Time Course

1. Chronic Heart Failure

• Stable symptoms for at least 1 month
• May be compensated with ongoing treatment

2. Acute Decompensated Heart Failure

• Sudden or gradual worsening of chronic heart failure
• Often leads to hospitalization
• Significant prognostic importance

3. New-onset Heart Failure

• May present acutely (e.g., after myocardial infarction)
• May present gradually (e.g., dilated cardiomyopathy) 1

Classification Based on Symptom Severity

The New York Heart Association (NYHA) functional classification:

• Class I: No limitation of physical activity
• Class II: Slight limitation of physical activity
• Class III: Marked limitation of physical activity
• Class IV: Unable to carry out any physical activity without discomfort 1

Classification Based on Development Stages

The American College of Cardiology Foundation/American Heart Association (ACCF/AHA) stages:

• Stage A: At risk for heart failure but without symptoms or structural heart disease
• Stage B: Structural heart disease but without symptoms (Pre-HF)
• Stage C: Structural heart disease with current or prior symptoms
• Stage D: Advanced heart failure requiring specialized interventions 3

Pathophysiological Differences Between Types

HFrEF and HFpEF have distinct pathophysiological mechanisms:

• HFrEF: More pronounced hypertrophic and fibrotic remodeling, diminished calcium release, and neurohormonal overactivation
• HFpEF: Greater inflammation, enhanced calcium release, and more pronounced protein hyperacetylation 4

Clinical Implications

Understanding the type of heart failure is crucial for appropriate management:

• HFrEF: Benefits from established neurohormonal therapies (beta-blockers, ACEIs/ARBs, MRAs)
• HFmrEF: May require treatment approaches from both HFrEF and HFpEF
• HFpEF: SGLT2 inhibitors have shown benefit; management focuses on comorbidities and symptom control 2

The classification of heart failure continues to evolve as our understanding of the pathophysiology improves, allowing for more targeted and effective treatments based on the specific type of heart failure.