World Health Organization functional class and brain natriuretic peptide levels (mean±SD) at baseline compared with 1 month and 1 year after onset of iNO treatment. *In Patients 1 and 2, the measure was taken at 6 months. BNP: brain natriuretic peptide. Reprinted from The Journal of Heart and Lung Transplantation, Vol 27, Gregorio Miguel Pérez-Peñate, Gabriel Juliá-Serdà, Nazario Ojeda-Betancort, Antonio García-Quintana, Juan Pulido-Duque, Aurelio Rodríguez-Pérez, Pedro Cabrera-Navarro, Miguel Angel Gómez-Sánchez, Long-term inhaled nitric oxide plus phosphodiesterase 5 inhibitors for severe pulmonary hypertension, Pages No. 1326–1332, Copyright (2008), with permission from the International Society for Heart and Lung Transplantation.[47]