Phenotypic Analysis of Pulmonary Hypertension Associated With Low Diffusion Capacity and Preserved Lung Function

Area of Science:

• Pulmonary Medicine
• Cardiology
• Radiology

Background:

• Severe diffusion impairment is noted in pulmonary arterial hypertension (PAH), especially idiopathic PAH (IPAH).
• Limited data exist on low diffusion capacity of the lungs for carbon monoxide (DLCO) with preserved lung function in broader pulmonary hypertension (PH) cohorts.
• Understanding these specific PH phenotypes is crucial for diagnosis and management.

Purpose of the Study:

• To investigate the characteristics and outcomes of PH patients with preserved lung function and low DLCO.
• To identify distinct phenotypic patterns within this patient group using hemodynamic and CT imaging data.

Main Methods:

• Analysis of 117 PH patients with preserved lung function and low DLCO, including CT scans.
• Categorization into "Parenchymal Type" (e.g., combined pulmonary fibrosis and emphysema, interstitial lung disease) and "Vascular Type" (e.g., pulmonary veno-occlusive disease, connective tissue disease) based on features.
• Assessment of patient demographics, hemodynamic data (mean pulmonary arterial pressure), and CT findings (emphysema, fibrosis, GGO).

Main Results:

• Two main phenotypes were identified: "Parenchymal Type" (69%) and "Vascular Type" (31%).
• "Parenchymal Type" patients were older, predominantly male, with emphysema and fibrosis.
• "Vascular Type" patients were younger, predominantly female, with centrilobular GGO. Idiopathic PAH patients showed mixed characteristics.
• The overall 5-year survival rate was poor at 31%.

Conclusions:

• PH patients with low DLCO and preserved lung function exhibit distinct "Parenchymal" and "Vascular" phenotypic patterns.
• These phenotypes are associated with significant lung abnormalities and a poor prognosis.
• Further research into targeted therapies for these distinct PH phenotypes is warranted.