Abstract
The prognosis of connective tissue disease (CTD)-associated pulmonary arterial hypertension (PAH) is so poor that early therapeutic intervention is advisable. Borderline PAH (21-24 mmHg mean pulmonary arterial pressure) is a concept created to distinguish cases that would become definite PAH. It is controversial whether borderline PAH cases with no symptoms should be treated, but therapeutic intervention in the case of borderline PAH is justified when systemic sclerosis (SSc) is in the background, because SSc-associated PAH shows an especially poor prognosis compared to PAH associated with other CTDs, while 42-55% of SSc-associated borderline PAH cases become definite PAH within several years. However, cautious attention should be paid when pulmonary vasodilators are administered to SSc-associated PAH cases, because complications caused by SSc such as lung lesions, left heart diseases and pulmonary venous lesions can be obstacles to the success of the therapy. There is very little evidence of the efficacy of therapeutic intervention in borderline PAH. Clinical trials should be planned.
