- Patients must be at least 18 years of age at study index;
- Patients must have a diagnosis of PAH. PAH is conventionally defined as a mean
pulmonary arterial pressure (PAP) of > 25 mmHg and a pulmonary capillary wedge
pressure (PCWP) ≤ 15 mmHg and a pulmonary vascular resistance (PVR) ≥ 240 dynes/s/cm-5
at right heart catheterization;
- Patients must have initiated sildenafil for the treatment of their PAH; at dose ≥ 20
mg tid within 5 years prior to study initiation
- Patient has known contraindications to sildenafil at study index;
- Patient participated in an investigational study of sildenafil treatment for PAH
during the period beginning 6 months prior to study index