Table 13.15-1. The World Health Organization functional classification for treatment and monitoring of patients with pulmonary hypertension

Class

Description

I

Patients with pulmonary hypertension but without resulting limitation of physical activity. Ordinary physical activity does not cause undue dyspnea or fatigue, chest pain, or near syncope

II

Patients with pulmonary hypertension resulting in slight limitation of physical activity. They are comfortable at rest. Ordinary physical activity causes undue dyspnea or fatigue, chest pain, or near syncope

III

Patients with pulmonary hypertension resulting in marked limitation of physical activity. They are comfortable at rest. Less than ordinary activity causes undue dyspnea or fatigue, chest pain, or near syncope

IV

Patients with pulmonary hypertension with inability to carry out any physical activity without symptoms. These patients manifest signs of right-heart failure. Dyspnea, fatigue, or both may even be present at rest. Discomfort is increased by any physical activity

Source: Eur Heart J. 2016;37(1):67-119.