Trends in pulmonary arterial hypertension

Past decades have witnessed an increasing interest in the field of pulmonary arterial hypertension (PAH). The large number of publications related to PAH reflects this interest. As a result, in contrast to 15 yrs ago, there are now at least seven different drugs as specific therapy targeting the pulmonary circulation that are approved for use in the USA and European Union, with some of them also approved for use in Canada, Japan, Australia and in some countries in Latin America. These medications have proved to increase exercise capacity [1–5], haemodynamics [2, 3, 6], quality of life [7–9] and even survival [5]. Nevertheless, there is still room for further improvements, since the mortality rate remains significantly high [10, 11]. Haemodynamically, PAH is characterised by progressive increase in pulmonary vascular resistance, as a consequence of vascular remodelling within the pre-capillary territory, leading to right ventricular failure and, eventually, death [12]; numerically, this is translated to the presence of a mean pulmonary artery pressure >25 mmHg, with normal pulmonary artery occlusion pressure (<15 mmHg) [13]. This definition, although extremely important for the proper characterisation of a pre-capillary impairment, might be misleading when focusing on specific patients or, more properly, specific forms of PAH. The most recent published nomenclature for pulmonary hypertension date from 2003 [13], and despite the fact that it has been recently revised (at the International Symposium of Pulmonary Hypertension, held in Dana Point, CA, USA, in the first quarter of 2008) it still includes in group 1 (PAH) several diseases that share the haemodynamic profile of pre-capillary pulmonary hypertension but present a completely distinct clinical course, such as idiopathic PAH, scleroderma-associated PAH and portopulmonary hypertension [10, 14, …