Circulating biomarkers in pulmonary arterial hypertension: update and future direction.

Pulmonary arterial hypertension (PAH) is a complex disease with a poor prognosis. In recent years, great advances have occurred in our understanding of the pathophysiologic mechanisms underlying the characteristic vascular proliferative lesions, thus allowing the development of several specific drugs. Nevertheless, PAH still presents a high mortality; therefore, early diagnosis and prognostic stratification seem to be of paramount importance in order to choose the best therapeutic strategies. Circulating biomarkers have been proposed as potentially noninvasive and objective parameters for diagnosis, prognosis, and response to therapy. The molecules evaluated to date, including markers of dysfunction and neurohormonal activation, myocardial injury, inflammation and oxidative stress, vascular damage and remodelling, end-organ failure, and gene expression, reflect the complex pathophysiology of PAH. However, not one of these shows all the characteristics of the ideal biomarker; thus, a multiparameter approach is probably desirable. Moreover, future direction could be research of structural proteins specifically expressed in the pathologic tissue that act as disease-specific markers. This report presents an extensive review of circulating biomarkers in PAH and some consideration about potential future direction in this area.