The aim of the study is to assess the efficacy and safety of different doses of BAY63-2521 given orally for 12 weeks, in patients with symptomatic Pulmonary Arterial Hypertension (PAH).
BAY63-2521: 1mg tid - 2.5mg tid orally for 12 weeks
BAY63-2521: 1.5mg tid orally for 12 weeks
Matching Placebo tid orally for 12 weeks
Capital Federal, Argentina