EDN1 and pulmonary arterial hypertension: The pathogenesis of PAH in the setting of HIV infection remains poorly understood despite new insights into the mechanistic roles of ADMA and the HIV proteins Nef and Tat.[7–9] A recent study by Feijoo et al. reported that plasma levels of ET-1 increased as the severity of HIV-associated PAH assessed non-invasively on TTE progressed.[24] In the present study, we observed a similar relationship between elevated levels of ET-1 and higher pulmonary artery pressures estimated by TTE.