What is a characteristic of Class I heart failure?

Class I heart failure, according to the New York Heart Association (NYHA) classification, is characterized by no limitations in physical activity. Patients in this class do not experience any symptoms of heart failure, such as shortness of breath, fatigue, or palpitations, during ordinary physical activities. This means they can carry out daily tasks without any cardiac symptoms hindering their performance.

In contrast, the other classifications indicate increasing severity of heart failure symptoms. Marked activity may lead to symptoms in Class II, mild activity while symptomatic in Class III, and symptoms at rest in Class IV. Therefore, the distinctive feature of Class I heart failure is the absence of any cardiac symptoms at all during usual activities, which sets it apart from the other classifications, where symptoms start to appear during different levels of activity.