C65-14 Prognostic Impact of Coexisting Lung Disease in Patients With Pulmonary Arterial Hypertension

Abstract Background Pulmonary arterial hypertension (PAH) is a progressive disorder of the pulmonary vasculature. A subset of patients with PAH present with concomitant lung disease (LD); however, the clinical significance of this overlap remains uncertain. Recent evidence suggests that PAH with coexisting LD may share pathophysiologic features and outcomes similar to those of Group 3 pulmonary hypertension (G3PH). This study aimed to investigate the clinical characteristics, hemodynamic profiles, and long-term outcomes of PAH with LD (PAH-LD) compared with PAH without LD (PAH-no LD) and G3PH. Methods We retrospectively analyzed consecutive patients diagnosed with PAH or G3PH at Hokkaido University Hospital between 2002 and 2024. Patients with mean pulmonary arterial pressure (mPAP) ≥25 mmHg were included, after excluding those with Group 2, 4, or 5 PH. Baseline computed tomography (CT) images were systematically reviewed to assess the presence and pattern of LD. Based on CT and pulmonary function test (PFT) findings, patients were classified as follows: those without radiologic or functional evidence of LD were defined as PAH-no LD; those with both emphysema and interstitial lung disease (ILD) were categorized as combined pulmonary fibrosis and emphysema (CPFE) and grouped into G3PH; and remaining patients were classified as PAH-LD or G3PH according to the extent and pattern of parenchymal abnormalities and spirometric findings. Baseline demographics, functional class, six-minute walk distance (6MWD), PFT, and right heart catheterization data were compared among the three groups. Survival was assessed using Kaplan-Meier analysis and compared by log-rank test. Prognostic factors were evaluated by Cox proportional hazards models restricted to PAH patients. Results A total of 158 patients were included (37 PAH-no LD, 39 PAH-LD, and 82 G3PH). Compared with PAH-no LD, PAH-LD patients were older, had lower diffusing capacity for carbon monoxide (DLCO), shorter 6MWD, and worse functional class, resembling G3PH. The 1-, 3-, and 5-year survival rates were 97%, 91%, and 77% in PAH-no LD; 90%, 71%, and 53% in PAH-LD; and 81%, 60%, and 38% in G3PH (p 0.001). In multivariable Cox analysis, concomitant LD independently predicted mortality (HR 4.80, 95% CI 1.15-19.99). Respiratory failure accounted for ∼40% of deaths in PAH-LD and G3PH, but none in PAH-no LD. Conclusions Nearly half of PAH patients had coexisting LD, which was associated with impaired exercise capacity and poorer prognosis, comparable to G3PH. Early recognition and phenotype-specific management are essential for this population. This abstract is funded by: None