The term connective tissue disease (CTD) refers to a group of autoimmune disorders that are classified among the systemic rheumatic diseases [1]. Pulmonary arterial hypertension (PAH) is a common and severe complication of such CTDs as systemic sclerosis (SSc), mixed CTD, systemic lupus erythematosus and, to a lesser extent, polymyositis-dermatomyositis, rheumatoid arthritis, antisynthetase syndrome and others [2–4]. CTD-associated PAH (CTD-PAH) is the second most prevalent type of PAH after idiopathic PAH (IPAH) in Western world, affecting 0.5–15% of patients with CTDs and is one of the leading causes of mortality in patients suffering from SSc and mixed CTD [5–7].
