Circulating Biomarkers in Pulmonary Arterial Hypertension: An Update

Pulmonary arterial hypertension (PAH) is a rare subtype of group 1 pulmonary hypertension
(PH) diseases, characterized by high pulmonary artery pressure leading to right ventricular
dysfunction and potential life-threatening consequences. PAH involves complex mechanisms: vasoconstriction,
vascular remodeling, endothelial dysfunction, inflammation, oxidative stress, fibrosis,
RV remodeling, cellular hypoxia, metabolic imbalance, and thrombosis. These mechanisms are
mediated by several pathways, involving molecules like nitric oxide and prostacyclin. PAH diagnosis
requires clinical evaluation and right heart catheterization, confirming a value of mPAP ≥ 20 mmHg
at rest and often elevated pulmonary vascular resistance (PVR). Even if an early and accurate diagnosis
is crucial, PAH still lacks effective biomarkers to assist in its diagnosis and prognosis. Biomarkers
could contribute to arousing clinical suspicion and serve for prognosis prediction, risk stratification,
and dynamic monitoring in patients with PAH. The aim of the present review is to report the main
novelties on new possible biomarkers for the diagnosis, prognosis, and treatment monitoring of PAH.