Early intervention for mild or borderline pulmonary arterial hypertension (PAH) associated with connective tissue diseases

INTERVENTION: Beraprost sodium Beraprost sodium and Sildenafil citrate CONDITION: Pulmonary arterial hypertension (PAH) associated with connective tissue disease PRIMARY OUTCOME: Time to clinical worsening INCLUSION CRITERIA: 1)Patients who are followed up at institutions in which this clinical trial is exected. 2)Patients who fulfill the classification criteria of collagen diseases such as SLE, SSc, PM/DM, and MCTD. 3)Mean pulmonary arterial pressure is over 20 mmHg and PCWP is less than 15 measured by right heart catheterization. 4) Patients classified as WHO functional class I or II