Treatment With Ambrisentan in Patients With Borderline Pulmonary Arterial Hypertension

This study is testing whether ambrisentan — a drug normally used for pulmonary arterial hypertension — can benefit people with borderline elevated pressure in the blood vessels of the lungs, before the condition progresses to full pulmonary arterial hypertension. **You may be eligible if...** - You are 18 years or older - Your mean pulmonary artery pressure (measured by right heart catheterisation) is between 21 and 24 mmHg, with normal wedge pressure (below 15 mmHg) - Your condition belongs to Group 1 pulmonary hypertension, which includes idiopathic, hereditary, connective tissue disease-related, HIV-related, portal hypertension-related, or congenital heart disease-related causes - You are willing to consent and comply with study procedures **You may NOT be eligible if...** - Your mean pulmonary artery pressure is above 25 mmHg (established pulmonary arterial hypertension) - Your elevated lung pressure is caused by heart failure or lung disease (Groups 2 or 3) - You have contraindications to ambrisentan Talk to your doctor to see if this trial is right for you.