Future of clinical trials for pulmonary hypertension.

In 1995, the first successful randomized controlled trial (RCT) for pulmonary arterial hypertension (PAH) led to the approval of the pulmonary vasodilator epoprostenol.1 Under the assumption that PAH was a disease of inappropriate pulmonary vasoconstriction, testing a drug that had vasodilator properties seemed reasonable. The 6-minute walk test was the primary end point in the trial because it was in keeping with the Food and Drug Administration precedent that an outcome assessment in a patient with cardiopulmonary disease needs to reflect how the patient feels, functions, or survives.