"Natural History" of pulmonary hypertension in a series of 131 patients with chronic obstructive lung disease

The prognostic value and the evolution of pulmonary hypertension (PH) in pa tients with markedly hypoxemic chronic obstructive pulmonary disease (COPD) , treated or not with long-term oxygen therapy (LTOT), has been extensively investigated. However, little is known in patients with mildly or moderate ly hypoxemic COPD not requiring LTOT. Therefore, we assessed the evolution of pulmonary hemodynamics in 131 patients with stable COPD by performing tw o right heart catheterizations at a mean ( SID) time interval of 6.8 +/- 2. 9 yr. At inclusion (T0), no patient had PH (i.e., the mean pulmonary artery pressure [Ppa] at rest was < 20 mm Hg). Group I included 55 patients witho ut exercising PH and group 2 included 76 patients with exercising PH, defin ed by a pulmonary arterial pressure (Ppa) > 30 mm Hg during a steady-state 40-W exercise. Group 2 patients compared with group I patients had a signif icantly higher resting Ppa (16 +/- 3 mm Hg versus 14 +/- 2 mm Hg, p = 0.001 ). At the second catheterization, 33 (25%) patients (9 of 55 in group 1, 24 of 76 in group 2, p = 0.048) showed a resting Ppa > 20 mm Hg, but PH was g enerally mild, ranging from 20 to 42.5 mm Hg. The mean Ppa at second evalua tion was 16 +/- 5 mm Hg in group 1 and 19 +/- 7 mm Hg in group 2 (p = 0.01) . The patients who developed resting PH at the second catheterization (TI) had higher resting and exercising Ppa (p = 0.001 and p = 0.002, respectivel y), and significantly lower resting and exercising Pa-O2 (p = 0.005 and p = 0.012, respectively) at TO. Logistic regression analysis showed that resti ng and exercising Ppa were independent predictors (at TO) for the subsequen t development of PH (p = 0.029 and p = 0.027, respectively). The patients w ho developed resting PH (TI) had a significantly worsening of Pa-O2 (from 6 3.5 mm Hg at T0 to 60 mm Hg at T1, p = 0.047), whereas the Pa-O2 as a mean was stable in the remainder (69.5 mm Hg at TO and T1). These results show t he following. The progression of Ppa over time in patients with COPD with m ild to moderate hypoxemia is rather slow, the average change for the group as a whole being of + 0.4 mm Hg/yr. Only about 25% of patients with COPD wi th mild to moderate hypoxemia and without resting PH at the onset will deve lop PH during a 6-yr follow-up. The patients with exercising PH at the onse t have a significantly increased risk of developing PH over time. Only rest ing and exercising Ppa at the onset are independently related to the subseq uent development of PH. However, in individual cases, the models of linear or logistic regression do not allow a pertinent prediction of the level of Ppa or the presence of PH at the second right heart catheterization.