Pulmonary arterial hypertension: from the kingdom of the near-dead to multiple clinical trial meta-analyses

Pulmonary arterial hypertension (PAH) is a rare and severe clinical condition characterized by a progressive increase of pulmonary vascular resistance leading to right ventricular failure and premature death (Figure 1). Its prevalence ranges from 15 to 50 patients per million population and it affects a relatively young patient population (average age of 50 years) when compared with the more common thoracic organ diseases such as coronary artery disease and chronic obstructive lung disease. PAH in adults includes at least nine clinical subgroups with virtually identical obstructive pathologic changes (Figures 1 and 2) in the distal pulmonary arteries: idiopathic, heritable, drugand toxin-induced, associated with, connective tissue diseases, HIV infection, portal hypertension, congenital heart disease, schistosomiasis, and chronic haemolytic anaemia.