Imaging-Based Pulmonary Hypertension Phenotypes in Connective Tissue Disease-Related Interstitial Lung Disease

Patients with connective tissue disease-related interstitial lung disease (CTD-ILD) may demonstrate pulmonary hypertension (PH) through pulmonary parenchymal destruction and chronic hypoxia or via endovascular changes driven by the underlying autoimmunity. Distinguishing which process-parenchymal or vascular-is the primary cause has important therapeutic and prognostic implications.

Can chest imaging be used to classify patients with CTD-ILD and PH systematically as having a parenchymal or vascular PH phenotype?

Chest CT imaging was used to classify 275 adult patients with CTD-ILD and PH in the Johns Hopkins ILD and PH registries as having a parenchymal or vascular PH phenotype. CT imaging-based PH phenotypes were determined using a validated ILD severity staging tool that involves visual inspection of the percentage of lung affected by CTD-ILD. The primary outcome was time to clinical worsening (defined as a composite of physiologic worsening, hospital admission for a pulmonary or cardiac diagnosis, lung transplantation, or death), which was compared between the 2 phenotypes. Secondary outcomes included comparisons of baseline cardiopulmonary testing results, time to physiologic worsening, time to hospital admission, and time to lung transplantation or death. Clinical outcomes also were compared between the CT imaging-based PH phenotypes and the conventional World Symposium on Pulmonary Hypertension (WSPH) group classifications.

Patients with CTD-ILD and the parenchymal PH phenotype were 1.76 times more likely to experience clinical worsening than those with the vascular phenotype. They were also more likely to experience physiologic worsening, hospitalization, and lung transplantation or death. CT imaging-based PH phenotypes were associated more closely with clinical outcomes than the WSPH group classifications.

Our research shows that patients with CTD-ILD and the parenchymal PH phenotype have worse clinical outcomes than those with the vascular PH phenotype. CT imaging-based PH phenotypes may characterize patients' risk of clinical worsening more reliably than the WSPH groups.