WHO Group I Classification of PAH

Pulmonary Arterial Hypertension (PAH) represents Group 1 within the Pulmonary Hypertension (PH) WHO clinical classification system (Venice 2003 revision) and is one of five such groups. The groups are divided based on etiology.¹

Group I. Pulmonary arterial hypertension (PAH)

• Idiopathic (IPAH)
• Familial (FPAH)
• Associated with (APAH):
• Connective tissue disease
• Congenital systemic-to-pulmonary shunts (e.g. Eisenmenger's)
• Portal hypertension
• Drugs and toxins
• Other (thyroid disorders, glycogen storage disease, Gaucher's disease, hereditary haemorrhagic telangiectasia, haemoglobinopathies, myeloproliferative disorders, splenectomy)
• Associated with significant venous or capillary involvement
• Pulmonary veno-occlusive disease (PVOD)
• Pulmonary capillary haemangiomatosis (PCH)
• Persistent pulmonary hypertension of the newborn (PPHN)

Group II. Pulmonary venous hypertension with left heart diseases

Group III. Pulmonary hypertension associated with respiratory diseases and/or hypoxemia (including chronic obstructive pulmonary disease)

Group IV. Pulmonary hypertension due to chronic thrombotic and/or embolic disease

Group V. Miscellaneous group

• e.g. sarcoidosis, histiocytosis X and lymphangiomatosis

Reference

1. J Am Coll Cardiol 2004; 43: Suppl S: 5S-12S