From the Guidelines
Pulmonary arterial hypertension (PAH) and pulmonary hypertension (pulmonary HTN) differ primarily in their classification and underlying causes, with PAH being a specific subtype of pulmonary hypertension, classified as Group 1, characterized by pre-capillary PH and pulmonary vascular resistance >3 Wood units, in the absence of other causes of pre-capillary PH 1.
Key Differences
- PAH is a clinical condition characterized by the presence of pre-capillary PH and pulmonary vascular resistance >3 Wood units, in the absence of other causes of pre-capillary PH such as PH due to lung diseases, chronic thromboembolic PH, or other rare diseases 1.
- Pulmonary hypertension, on the other hand, is a broader umbrella term that encompasses all conditions causing elevated pressure in the pulmonary circulation, defined as mean pulmonary arterial pressure ≥25 mmHg at rest, and includes five different groups based on cause: Group 1 (PAH), Group 2 (due to left heart disease), Group 3 (due to lung diseases/hypoxia), Group 4 (chronic thromboembolic pulmonary hypertension), and Group 5 (unclear/multifactorial mechanisms) 1.
Classification and Treatment
- The classification of PAH and pulmonary hypertension is crucial in determining the treatment approach, with PAH-specific therapies including endothelin receptor antagonists, phosphodiesterase-5 inhibitors, prostacyclin analogs, and soluble guanylate cyclase stimulators 1.
- Other forms of pulmonary hypertension primarily focus on treating the underlying cause rather than using these PAH-specific medications, and the treatment approach may vary depending on the underlying cause and the severity of the disease 1.
Clinical Implications
- The distinction between PAH and pulmonary hypertension is essential in clinical practice, as it guides the treatment approach and affects patient outcomes, with PAH requiring specific therapies and close monitoring to slow disease progression and improve quality of life 1.
- Accurate diagnosis and classification of PAH and pulmonary hypertension are critical to ensure optimal treatment and management of these complex diseases, and expert referral centers play a crucial role in the management of patients with PAH and pulmonary hypertension 1.
From the Research
Definition and Classification
- Pulmonary arterial hypertension (PAH) is a subtype of pulmonary hypertension (PH), characterized by pulmonary arterial remodeling 2.
- PH is defined by a mean pulmonary artery pressure greater than 20 mm Hg and is classified into 5 clinical groups based on etiology, pathophysiology, and treatment 2, 3.
- PAH is hemodynamically defined by right heart catheterization demonstrating a mean pulmonary artery pressure greater than 20 mm Hg, a pulmonary artery wedge pressure of 15 mm Hg or lower, and a pulmonary vascular resistance of 3 Wood units or greater 2.
Key Differences
- PAH is a specific type of PH, whereas PH is a broader term that encompasses several clinical groups, including PAH, PH due to left-sided heart disease, PH due to chronic lung disease, chronic thromboembolic PH, and PH with unclear and/or multifactorial mechanisms 3.
- PAH is characterized by elevated pressures within the pulmonary vascular tree, whereas PH can result from a range of underlying conditions, including left-sided heart disease, chronic lung disease, and thromboembolic disease 4, 5.
Diagnosis and Treatment
- Diagnosis of PAH requires evidence of a mean pulmonary artery pressure >20 mmHg, a pulmonary vascular resistance >2 Wood units, and a pulmonary artery wedge pressure ≤15 mmHg at right heart catheterization 4.
- Treatment of PAH typically involves combination therapy targeting multiple biological pathways, including the nitric oxide, endothelin, and prostacyclin signaling pathways 2, 5.
- Targeted treatments, such as phosphodiesterase type 5 inhibitors, soluble guanylate cyclase stimulators, endothelin receptor antagonists, prostacyclin analogues, and prostacyclin receptor agonists, are licensed for patients with PAH 3.