Heart Failure - Classification

Classification

There are many different ways to categorize heart failure, including:

• the side of the heart involved (left heart failure versus right heart failure). Right heart failure compromises pulmonary flow to the lungs. Left heart failure compromises aortic flow to the body and brain. Mixed presentations are common; left heart failure often leads to right heart failure in the longer term.
• whether the abnormality is due to insufficient contraction (systolic dysfunction), or due to insufficient relaxation of the heart (diastolic dysfunction), or to both.
• whether the problem is primarily increased venous back pressure (preload), or failure to supply adequate arterial perfusion (afterload).
• whether the abnormality is due to low cardiac output with high systemic vascular resistance or high cardiac output with low vascular resistance (low-output heart failure vs. high-output heart failure).
• the degree of functional impairment conferred by the abnormality (as reflected in the New York Heart Association Functional Classification)
• the degree of coexisting illness: i.e. heart failure/systemic hypertension, heart failure/pulmonary hypertension, heart failure/diabetes, heart failure/renal failure, etc.

Functional classification generally relies on the New York Heart Association functional classification. The classes (I-IV) are:

• Class I: no limitation is experienced in any activities; there are no symptoms from ordinary activities.
• Class II: slight, mild limitation of activity; the patient is comfortable at rest or with mild exertion.
• Class III: marked limitation of any activity; the patient is comfortable only at rest.
• Class IV: any physical activity brings on discomfort and symptoms occur at rest.

This score documents severity of symptoms, and can be used to assess response to treatment. While its use is widespread, the NYHA score is not very reproducible and doesn't reliably predict the walking distance or exercise tolerance on formal testing.

In its 2001 guidelines the American College of Cardiology/American Heart Association working group introduced four stages of heart failure:

• Stage A: Patients at high risk for developing HF in the future but no functional or structural heart disorder.
• Stage B: a structural heart disorder but no symptoms at any stage.
• Stage C: previous or current symptoms of heart failure in the context of an underlying structural heart problem, but managed with medical treatment.
• Stage D: advanced disease requiring hospital-based support, a heart transplant or palliative care.

The ACC staging system is useful in that Stage A encompasses "pre-heart failure" — a stage where intervention with treatment can presumably prevent progression to overt symptoms. ACC Stage A does not have a corresponding NYHA class. ACC Stage B would correspond to NYHA Class I. ACC Stage C corresponds to NYHA Class II and III, while ACC Stage D overlaps with NYHA Class IV.