Résumé : OBJECTIVES: The purpose of this study was to assess the efficacy and safety of beraprost sodium, an orally active prostacyclin analogue, in New York Heart Association (NYHA) functional class II and III patients with pulmonary arterial hypertension (PAH). BACKGROUND: Pulmonary arterial hypertension is a life-threatening disease for which continuous intravenous infusion of prostacyclin has been proven effective. However, this treatment is associated with serious complications arising from the complex delivery system. METHODS: In this double-blind, placebo-controlled study, 130 patients with PAH were randomized to the maximal tolerated dose of beraprost (median dose 80 μg four times a day) or to placebo for 12 weeks. The primary end point was the change in exercise capacity assessed by the 6-min walk test. Secondary end points included changes in Borg dyspnea index, cardiopulmonary hemodynamics and NYHA functional class. RESULTS: Patients treated with beraprost improved exercise capacity and symptoms. The difference between treatment groups in the mean change of 6-min walking distance at week 12 was 25.1 m (95% confidence interval [CI]: 1.8 to 48.3, p = 0.036). The difference in the mean change of Borg dyspnea index was -0.94 (95% CI: -1.63 to -0.24, p = 0.009). In the sub-group of patients with primary pulmonary hypertension, the difference in the mean change of 6-min walking distance was 46.1 m (95% CI: 3.0 to 89.3, p = 0.035). Cardiopulmonary hemodynamics and NYHA functional class had no statistically significant changes. Drug-related adverse events were common in the titration phase and decreased in the maintenance period. CONCLUSIONS: Beraprost improves exercise capacity and symptoms in NYHA functional class II and III patients with PAH and, in particular, in those with primary pulmonary hypertension. © 2002 by the American College of Cardiology Foundation.