Pulmonary hypertension: classification, epidemiology, haemodynamic characteristics, and treatments
| Classification* | Epidemiology | Haemodynamic characteristics† | Treatment |
| Group 1‡ | |||
| Idiopathic PAH Heritable PAH PAH induced by drugs or toxins PAH associated with: connective tissue disease, HIV infection, portal hypertension, congenital heart disease, schistosomiasis, pulmonary veno-occlusive disease-pulmonary capillary haemangiomatosis, persistent PH of the newborn | Incidence of 1.1-7.5 patients/million adults/year. Prevalence of 6.6-26.0 patients/million adults.3 Estimated >200 million people infected worldwide with Schistosoma276; prevalence of Schistosoma PH understudied | Precapillary PH: mPAP >20 mm Hg PAWP ⩽15 mm Hg PVR ⩾3 Woods units† | Pulmonary vasodilators (phosphodiesterase type 5 inhibitors, endothelin receptor antagonists, soluble guanylate cyclase, prostacyclin and prostacyclin analogues, calcium channel blockers in responders to acute vasodilator challenge) |
| Group 2‡ | |||
| Heart failure with preserved LVEF Heart failure with reduced LVEF Valvular heart disease Congenital or acquired cardiovascular conditions leading to postcapillary PH | Most common form of PH, accounting for 65-80% of patients with 3PH PH affects >50% of patients with left ventricular heart failure277 | Postcapillary PH mPAP >20 mm Hg PAWP >15 mm Hg PVR <3 Woods units Or combined precapillary and postcapillary PH mPAP >20 mm Hg PAWP >15 mm Hg PVR 3 Woods units | Treat left heart disease Maintain euvolaemia with diuretics, sodium, and fluid restriction Control systemic hypertension |
| Group 3‡ | |||
| Obstructive lung disease (ie, COPD-PH, OSA) Restrictive lung disease (ie, ILD-PH) Other lung disease with mixed restrictive or obstructive pattern Hypoxia without lung disease including high altitude Developmental lung disorders | Second most common form of PH after left heart disease3 5-25% of patients with mild to moderate COPD; up to 90% in patients with severe COPD278 279 38-80% in advanced idiopathic pulmonary fibrosis280–282 | Precapillary PH: mPAP >20 mm Hg PAWP ⩽5 mm Hg PVR ⩾3 Woods units† | Treat underlying disease Supplemental oxygen or non-invasive positive pressure ventilation, or both, to maintain SpO2 ⩾90% and PaCO2 ⩽ 40 mm Hg Inhaled trepostinil (approved for ILD-PH only) |
| Group 4‡ | |||
| Chronic thromboembolic PH Malignant and non-malignant tumours Arteritis without connective tissue disease Congenital pulmonary artery stenosis Parasites (hydatidosis) | Incidence of 2-6 and prevalence of 26-38 patients/million adults283–285 | Precapillary PH: mPAP >20 mm Hg PAWP ⩽15 mm Hg PVR ⩾3 Woods units† | Treat underlying disease For chronic thromboembolic PH: Pulmonary thromboendarterectomy Balloon pulmonary angioplasty Pulmonary vasodilators (soluble guanylate cyclase) |
| Group 5‡ | |||
| Haematological disorders Systemic and metabolic disorders Sarcoidosis Chronic renal failure Fibrosing mediastinitis Complex congenital heart disease | Mostly unknown Prevalence of PH in sarcoidosis 6-20% at rest and up to 43% with exercise286 | Predominantly precapillary PH, but includes postcapillary and combined pre- and postcapillary PH | Treat underlying disease Pulmonary vasodilator treatment can be used off label in some patients |
COPD=chronic obstructive pulmonary disease; COPD-PH=pulmonary hypertension related to COPD; ILD-PH=pulmonary hypertension related to interstitial lung disease; LVEF=left ventricular ejection fraction; mPAP=mean pulmonary arterial pressure; OSA=obstructive sleep apnoea; PaCO2=partial pressure of carbon dioxide in arterial blood; PAH=arterial hypertension; PAWP=pulmonary arterial wedge pressure; PH=pulmonary hypertension; PVR=pulmonary vascular resistance; SpO2=arterial oxygen saturation measured by pulse oximeter.
*According to the Sixth World Symposium on Pulmonary Hypertension.
†Defined by Sixth World Symposium on Pulmonary Hypertension, 2018. The 2022 European Respiratory Society-European Society of Cardiology guidelines suggest a cut-off for pulmonary vascular resistance of 2 Woods units.
‡Pulmonary hypertension is clinically divided into five groups: pulmonary arterial hypertension (group 1), pulmonary hypertension caused by left heart disease (group 2), pulmonary hypertension caused by lung diseases, hypoxia, or both (group 3), chronic thromboembolic pulmonary hypertension and pulmonary hypertension caused by pulmonary artery obstructions (group 4), and pulmonary hypertension caused by unclear or multifactorial mechanisms (group 5).