Heart Failure Classification

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

the side of the heart involved, (left heart failure versus right heart failure)
whether the abnormality is due to contraction or relaxation of the heart (systolic dysfunction vs. diastolic dysfunction)
whether the problem is primarily increased venous back pressure (behind) the heart, or failure to supply adequate arterial perfusion (in front of) the heart (backward vs. forward failure)
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 in the NYHA functional classification)

''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.

Diagnostic criteria

No system of diagnostic criteria has been agreed as the gold standard for heart failure. Commonly used systems are the "Framingham criteria" (derived from the Framingham Heart Study), the "Boston criteria", the "Duke criteria", and (in the setting of acute myocardial infarction) the "Killip class".

Heart Failure Classification

Diagnostic criteria

Further Reading

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