NYHA classification for chronic heart failure (CHF)

New York Heart Association (NYHA) classification is used to grade the severity of functional limitations in a patient with heart failure (1):

• class I no limitation of physical activity
  • ordinary physical activity does not cause fatigue, breathlessness or palpitation (includes asymptomatic left ventricular dysfunction)
    
    
• class II slight limitation of physical activity
  • patients are comfortable at rest. Ordinary physical activity results in fatigue, palpitation, breathlessness or angina pectoris (symptomatically 'mild' heart failure)
    
    
• class III marked limitation of physical activity
  • although patients are comfortable at rest, less than ordinary activity will lead to symptoms (symptomatically 'moderate' heart failure)
    
    
• class IV inability to carry out any physical activity without discomfort
  • symptoms of congestive cardiac failure are present even at rest. Increased discomfort with any physical activity (symptomatically 'severe' heart failure)

According to a study conducted, the following criteria were used by cardiologists to determine the NYHA class of a patient (cardiologists could use multiple criteria for assessment):

• self reported walking distance - 70%
• difficulty in climbing stairs - 60%
• ability to walk to local landmarks - 30%
• breathlessness interferes with daily activities - 23%
• breathless when walking around the house - 23%
• no specific questions - 13% (1)

This study has also pointed out that NYHA classification system is subjective and poorly reproducible since there are no clear standard criteria for assigning an NYHA class (1).

Note:

• the functional class tends to deteriorate unevenly overtime, so the severity of the symptoms cannot be compared with the severity of the underlying problem e.g. – patients with severe disease may have mild symptoms and vice versa
• favourable or adverse effects on functional capacity can occur with changes in medication and diet in the absence of any measurable changes in heart function (3)

Reference:

• (1) Raphael C et al. Limitations of the New York Heart Association functional classification system and self-reported walking distances in chronic heart failure. Heart. 2007;93(4):476-82
• (2) MeReC Bulletin 2008; 18 (3):1-9.
• (3) National Institute for Health and Clinical Excellence (NICE) 2010. Chronic heart failure. National clinical guideline for diagnosis and management in primary and secondary care