a Non-interventional Study of Sildenafil in the Treatment of Pulmonary Arterial Hypertension (PAH) in Adults From China

Inclusion Criteria: * At least 18 years of age at study index date; (The index date (i.e., Day 1 of the study) is the date when the first sildenafil dose was actually taken, after Revatio® is approved by China authority) * A diagnosis of PAH with a mean pulmonary artery pressure of ≥25 mmHg and a mean pulmonary capillary wedge pressure of ≤15 mmHg by right heart catheterization; * Initiated sildenafil for the treatment of their PAH based on treatment suggestion from physician ;(Patients who have received sildenafil or are receiving sildenafil are eligible to participate in this study if they met the above inclusion criteria and were ready to start sildenafil (Revatio®) for treatment at screening;) * Evidence of a personally signed and dated informed consent document indicating that the patient (or a legally acceptable representative) has been informed of all pertinent aspects of the study. Exclusion Criteria: * No