Expansion
Four classes, graded by the activity that causes symptoms
Expansion
- Class I - no limitation. Ordinary activity causes no symptoms
- Class II - slight limitation. Comfortable at rest, ordinary activity causes symptoms
- Class III - marked limitation. Comfortable at rest, less than ordinary activity causes symptoms
- Class IV - symptoms at rest, and any activity increases discomfort
“I none, II ordinary, III less than ordinary, IV at rest.”
It is a functional grade, not a structural one, so it is independent of the ejection fraction: a patient with an ejection fraction of 20 per cent may be class II on good treatment, and one with a preserved fraction may be class IV.
The ACC/AHA stages run alongside and are structural and irreversible: A at risk with no structural disease, B structural disease without symptoms, C structural disease with symptoms, D refractory disease needing specialist intervention.
“NYHA class can improve; ACC stage cannot go backwards.” That is the useful distinction between the two systems, and it is why both are quoted.