EDNRA and pulmonary arterial hypertension: With available therapeutic options (including phosphodiesterase inhibitors, prostacyclin analogues, and dual-receptor or single-receptor (ET-A) endothelin blockade) and given the irreversibility of advanced pathology associated with PAH, an impetus is provided for earlier detection of PAH in at-risk populations, with exercise proposed as a useful stress tool, albeit a method yet to possess clear normal cutoff ranges.