Progression of mean pulmonary arterial pressure in idiopathic pulmonary fibrosis with mild to moderate restriction

Background and objective: Elevation of mean pulmonary arterial pressure (MPAP) is associated with poor prognosis in patients with idiopathic pulmonary fibrosis (IPF), yet the progression of MPAP in patients with IPF has not been sufficiently elucidated. We evaluated serial changes in MPAP and its determinants in patients with IPF with mild to moderate restriction.

Methods: We retrospectively reviewed patients with IPF who underwent initial evaluations including right heart catheterization (RHC) in our institute from May 2007 to December 2013 with follow-up RHC at least 1 year later. Patients with forced vital capacity (FVC) < 50% predicted or those with pulmonary artery wedge pressure >15 mm Hg were excluded.

Results: A total of 95 patients were included. Median follow-up time of second RHC was 1.8 years. MPAP increased significantly at follow-up (from 16.8 to 20.2 mm Hg; P < 0.001), and annual change in MPAP (ΔMPAP) was 1.8 mm Hg/year. In multiple regression analysis, the lowest oxygen saturation (SpO₂ ) at 6-min walk test (6MWT) was an independent predictor of ΔMPAP. When adjusted for age, sex, baseline MPAP and FVC % predicted, ΔMPAP was a significant predictor of mortality (hazard ratio: 1.21; P = 0.001).

Conclusion: ΔMPAP was significantly associated with desaturation in the 6MWT, and with increased mortality in patients with IPF with mild to moderate restriction.