The Endothelin Antagonist Trial in Mildly Symptomatic PAH Patients (EARLY) involved 29 patients with PAH on sildenafil at baseline out of a total of 185 patients in the EARLY registry.

• 轻度肺动脉高压患者内皮素拮抗剂试验(EARLY)共登记185例PAH患者，选择基线状态使用西地那非的29例患者进行研究。