Systemic Sclerosis and Other Connective Tissue Diseases

Abstract

Pulmonary hypertension (PH) is an important and relatively frequent complication of connective tissue disease (CTD). It is most often seen as a complication of systemic sclerosis and mixed CTD, but is also recognized in systemic lupus erythematosus and other related conditions. Although PH is defined hemodynamically by mean pulmonary arterial pressure (mPAP) of ≥25 mm Hg at right heart catheterization, and may have a variety of mechanisms, it is World Health Organization (WHO) Group 1 pulmonary arterial hypertension (PAH) that has deservedly received the most attention in CTD. The inclusion of cases of precapillary PH without other explanation or concurrent lung fibrosis in WHO Group 1 led to availability of licensed therapies and increased the need for screening and treatment. Approaches are now available that detect PAH, and optimal approaches to therapy are included in expert and evidence-based recommendations. Challenges include borderline elevation of mPAP, comorbidity, and mixed-etiology cases. Overall outcomes have improved, and new clinical trials are being performed that will hopefully build on recent progress to further improve outcomes. Other aspects of PH in CTD to consider include forms related to cardiac disease and lung fibrosis or hypoxia, as these may occur as complications of the underlying CTD. Thromboembolic disease may also occur and represents another important differential diagnosis. Finally, it has been reported that pulmonary veno-occlusive disease may occur, which raises diagnostic and treatment difficulties. Overall, there are major challenges in CTDPH, but also opportunities for effective multispecialty care and early detection and diagnosis of potentially treatable cases of PAH.