Evolution and prognosis of pulmonary hypertension in chronic obstructive pulmonary diseases

The prognostic value of the presence and degree of pulmonary arterial hypertension (PAH) in chronic obstructive pulmonary diseases (COPD) has been well established by recent studies including the European WHO multicentric study where 591 COPD patients have been included. The level of pulmonary artery mean pressure (PAP) is one of the best predictors of mortality in these patients along with FEV1 and arterial blood gases. The natural history of the course of PAP in COPD was relatively obscure until recent years. The first studies in that field were performed in 1968 but included small numbers of patients. In consideration of the data of three studies published in 1977 to 1979 which concern a relatively homogeneous group of 163 patients with severe COPD, it appears that changes in PAP after an average follow-up period of four years are rather small from 21.4 to 23.6 mm Hg (0.5 to 0.6 mm Hg/year). These results have been confirmed by a very recent study of our group including 93 COPD patients followed-up for five to twelve years (mean = 90 months): the yearly increase in PAP was of only 0.5 mm Hg. Long-term oxygen therapy (LTO) for greater than or equal to 15 h/day rarely normalizes PAP, but can reverse the progression of PAH, particularly in those patients who exhibit a marked worsening of PAH due to a progressive deterioration of arterial blood gases. Very recent studies have clearly indicated that LTO had beneficial hemodynamic effects in a high percentage of COPD patients with PAH.