Prevalence of Pulmonary Hypertension in Patients with Idiopathic Pulmonary Fibrosis: Correlation with Physiological Parameters

The aim of this study was to prospectively evaluate the prevalence of pulmonary hypertension (PH) in patients with idiopathic pulmonary fibrosis (IPF). One hundred thirty-nine patients (101 male, mean age = 68.6 ± 9 years), with confirmed IPF and who were admitted to eight Pulmonary Departments in Greece between November 2005 and December 2006 were included in the study. Pulmonary artery systolic pressure (PASP) was estimated by echocardiography, and PH was defined as PASP > 36 mmHg. We compared demographics, pulmonary function tests, NYHA functional status, 6-min walk distance (6MWD), B-type natriuretic peptide (BNP), PaO₂, and P(A-a)O₂ at rest data between patients with PH and without PH (PASP ≤ 36 mmHg). Increased estimated right ventricular systolic pressure was present in 55% of patients (mean PASP = 47.1 ± 11.2 mmHg vs. 30.3 ± 3.8 mmHg, respectively). Patients with PH had a lower but not statistically significant DL_CO (47.1 ± 18.8 vs. 52.5 ± 20.1), lower PaO₂ at rest (64.6 ± 12.2 vs. 71.1 ± 11.3, P = 0.004), and lower mean 6MWD (282 ± 118 vs. 338 ± 91, P = 0.007). Significant differences were also observed in the NYHA functional status between the two groups (P = 0.02). Statistically significant correlations were observed between PASP and PaO₂ at rest (r = −0.331, P = 0.00), P(A-a)O₂ at rest (r = 0.494, P = 0.00)_, 6MWD (r = −0.264, P = 0.01), SpO₂ at rest (r = −0.293, P = 0.00), SpO₂ at the end of exercise (r = −0.364, P = 0.00), and also BNP values (r = 0.319, P = 0.01). Moreover, PaO₂ (P = 0.02), P(A-a)O₂ (P = 0.005), and SpO₂ at the end of exercise (P = 0.023) were independent predictors of the presence of estimated PH. Using Doppler echocardiography as a screening tool for the estimation of PH, we found that PH is common in patients with IPF. Gas exchange parameters at rest and exercise desaturation might indicate underlying PH in IPF.