Symptoms are described using the New York Heart Association (NYHA) functional class I-IV (Table 1).

Table 1: New York Heart Association functional classification and other symptom descriptors
Class	Definition	Other Descriptor
I	No symptoms	Asymptomatic
II	Symptoms with ordinary activity	Mild symptoms
III	Symptoms with less than ordinary activity	Moderate symptoms
IV	Symptoms at rest or with any minimal activity	Severe symptoms

Data from the Criteria Committee of the New York Heart Association.