Pulmonary hypertension in systemic sclerosis: different phenotypes

Pulmonary hypertension (PH) is a frequent and severe complication of systemic sclerosis (SSc). PH in SSc is highly heterogeneous because of the various clinical phenotypes of SSc itself and because the mechanisms of PH can vary from one patient to another. PH in SSc may be due to vasculopathy of the small pulmonary arteries (group 1; pulmonary arterial hypertension), interstitial lung disease (group 3; PH due to lung disease or chronic hypoxia) or myocardial fibrosis leading to left ventricular systolic or diastolic dysfunction (group 2; PH due to chronic left-heart disease). Pulmonary veno-occlusive disease is not uncommon in SSc and may also cause PH in some patients (group 1'). There is a high prevalence of each of these conditions in SSc and, as such, it may be difficult to determine the dominant cause of PH in a particular patient. However, careful phenotyping of PH in SSc is important as the therapy required for each of these underlying conditions is very different. In this review, we will decipher the different phenotypes of SSc-PH.