Table 3

Class I: No limitation of ordinary physical activity.

Class II: Mild limitation of ordinary physical activity. No discomfort at rest.

Class III: Marked limitation of physical activity even with less than ordinary activity. No discomfort at rest.

Class IV: Unable to perform any physical activity and symptomatic even at rest.

Limitations to physical activity in each class may be due to increased dyspnea,
chest pain, fatigue or syncope

Table 3: WHO functional classification of PAH.