The prevalence of PAH varies among specific populations, but one study estimated that it affects 15 in 1 million adults.1 Idiopathic PAH occurs mainly in persons in their 20s and 30s, with an overall female-to-male ratio of 1.7:1, which is higher in black persons (4.3:1).2 Risk factors for PAH include a family history of PAH, congenital heart disease, connective tissue disease, portal hypertension