- Male or female patients ≥18 years of age with a current diagnosis of pulmonary arterial hypertension (PAH) according to the Dana Point 2008 Meeting: World Health Organization (WHO) Diagnostic Group I, idiopathic or heritable (familial or sporadic) PAH, PAH associated with collagen vascular disease including systemic sclerosis, rheumatoid arthritis, mixed connective tissue diseases, and overlap syndrome. PAH following one year repair of congenital heart defect [Atrial Septal Defect (ASD), Ventricular Septal Defect (VSD) or Posterior Descending Artery (PDA)], or PAH associated with diet therapies or other drugs