Pulmonary arterial hypertension in connective tissue disorders: Pathophysiology and treatment

Abstract

Pulmonary arterial hypertension (PAH) is a serious complication of connective tissue disorders (CTDs), and CTD-PAH is the second cause of PAH after the idiopathic form. PAH is characterized by increased pulmonary arterial pressure and pulmonary vascular resistance, which can lead to right heart failure and death. About 90% of CTD-PAH cases are associated with systemic sclerosis (SSc, 74%), mixed connective tissue disease (MCTD, 8%) or systemic lupus erythematosus (SLE, 8%). CTD-PAH has also been reported, albeit rarely, in Sjögren syndrome, inflammatory idiopathic myopathies and rheumatoid arthritis. As for idiopathic PAH, the impaired production of vasoactive mediators such as nitric oxide and prostacyclin, and the increased production of vasoconstrictors and proliferative mediators such as endothelin-1, affect the vascular tone and promote vascular remodeling. Moreover, there is growing evidence suggesting that inflammation and autoimmunity may contribute to the genesis and progression of CTD-PAH, especially in SLE and MCTD patients who require an early administration of corticosteroids and immunosuppressants in order to avoid irreversible pathologic changes in pulmonary vessels. Conversely, immunosuppressive agents are ineffective in SSc-PAH, which requires a timely and aggressive treatment with specific PAH therapies (combination therapy). In this review, we summarized the current data on the pathophysiology and treatment of CTD-PAH. Impact statement Our article focuses on the pathogenesis and treatment of CTD-PAH. In the latest ESC/ESR guidelines for PAH, the authors underline that although CTD-PAH should follow the same treatment protocol as idiopathic PAH, the therapeutic approach is more complex and difficult in the former. This review throws light on several peculiar aspects of CTD-PAH and the latest findings in the pathogenesis, namely, the role of inflammation in the maladaptive right ventricle remodeling in SSc-PAH where immunosuppressants are classically believed to be ineffective. Furthermore, we discuss the major critical points in the therapy of CTD-PAH which is one of the strengths of our article. To the best of our knowledge, there are no other reviews that exclusively focus on the pathogenesis and treatment of CTD-PAH patients, with an emphasis on the more critical issues. Thus, it is our contention that our work would be of interest to the readers.