Congestive heart failure classification

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Mitra Chitsazan, M.D.[2], Sara Zand, M.D.[3] Jair Basantes de la Calle, M.D.

LVEF has an important role in the classification of patients with HF because of differing prognosis and response to treatments. In the guideline of 2022 AHA, HFrEF is defined as LVEF ≤40% . HF with preserved EF (HFpEF) including approximately 50% of the population with HF with increased prevalence. HFpEF is defined as LVEF ≥50%. Heaet failure improved EF is considered when follow-up LVEF reaches more than 40%.

Several classification systems are used to characterize heart failure according to the: ^{[1] [2]}

• The pathophysiology of heart failure:
  • Systolic vs diastolic heart failure
  • Left-sided, right-sided or biventricular heart failure
  • Low output vs high output heart failure
• The underlying physiology based on left ventricular ejection fraction:
  • Heart failure with reduced ejection fraction (HFrEF), heart failure with mid-range ejection fraction (HFmrEF), heart failure with preserved ejection fraction (HFpEF)
• The chronicity of heart failure:
  • acute or chronic
• The severity of symptoms of heart failure:
  • New York Heart Association Class (NYHA class)
  • Killip class (severity of the symptoms in the acute setting after myocardial infarction)
• The stage (progression of the disease) of congestive heart failure:
  • The American College of Cardiology Foundation/American Heart Association (ACCF/AHA) classification: A, B, C, D.

• Systolic Dysfunction: The left ventricular ejection fraction is reduced in systolic dysfunction and there is depressed contractility of the heart.
• Diastolic Dysfunction: The left ventricular ejection fraction is preserved in diastolic dysfunction and there is an abnormality in myocardial relaxation or excessive myocardial stiffness. Systolic and diastolic dysfunction commonly occur in conjunction with each other.

Another common method of classifying heart failure is based upon the ventricle involved.

• Left-ventricular Heart Failure: There is impaired left ventricular function with the reduced flow into the aorta.
• Right-ventricular Heart Failure: There is impaired right ventricular function with the reduced flow into the pulmonary artery and lungs.
• Biventricular Failure: The most common cause of right heart failure is left heart failure, and mixed presentations are common, especially when the cardiac septum is involved.

• Low Output Failure: The cardiac output is reduced, and the systemic vascular resistance (SVR) is high. In low output failure, there is an inadequate supply of blood flow to meet normal metabolic demands.
• High Output Failure: The cardiac output is increased, and the systemic vascular resistance (SVR) is low. Rather than an inadequate supply of blood flow to meet normal metabolic demands as occurs in low output failure, in high output failure there is an excess requirement for oxygen and nutrients and the demand outstrips what the heart can provide.^[3] Causes of high output heart failure include severe anemia, Gram negative septicaemia, beriberi (vitamin B₁/thiamine deficiency), thyrotoxicosis, Paget’s disease, arteriovenous fistulae, or arteriovenous malformations.

• HFrEF is defined as LVEF <_40% or significant reduction in LV systolic function.
• HFmrEF is defined when LVEF is between 41% and 49% or there is mildly reduced LV systolic function.
• HF p EF is defined as LVEF >_50%, with symptoms and signs of heart failure , with evidence of structural and/or functional cardiac abnormalities and/or high level of natriuretic peptides (NPs).

Abbreviations: HF: Heart failure; HFmrEF: Heart failure with mildly reduced ejection fraction; HFpEF: Heart failure with preserved ejection fraction ; HFrEF: Heart failure with reduced ejection fraction; LV: Left ventricle; LVEF: Left ventricular ejection fraction;

^[4]

^[5]

• Acute or Decompensated: Acute or decompensated heart failure is a term used to describe exacerbated or decompensated heart failure, and refers to an episode in which a patient sustains a change in heart failure signs and symptoms that necessitates urgent therapy or hospitalization.^[6]
• Chronic: There is stable symptomatology in chronic heart failure.

The NYHA functional classification is used to describe the severity of symptoms and exercise intolerance in patients with congestive heart failure.

The ACC/AHA classification system was introduced to emphasize the natural history of the heart failure syndrome and to identify opportunities to intervene earlier and prevent disease progression.

^[5]