Pulmonary arterial Hypertension (PAH)
Pulmonary hypertension (PH) is characterized by the progressive increase in pulmonary vascular resistance eventually leading to right ventricular failure and premature death. It is defined as a resting mean pulmonary arterial pressure (mPAP) higher than 25 mm Hg measured by right heart catheterization.
According to the latest classification of PH (known as Dana Point classification) this condition can be secondary to a number of disorders, including pulmonary diseases and/or hypoxemia, left heart disease, thromboembolic disease of the pulmonary arteries, and a miscellanea of other causes, such as sarcoidosis and lymphangiomyomatosis.
For the diagnosis of the subclass known as pulmonary arterial hypertension (PAH), a pulmonary arterial wedge pressure lower than 15 mm Hg is required.
PAH associated with systemic autoimmune diseases is included within group I of the Dana Point classification. PAH is a recognized complication of this group of diseases, particularly systemic sclerosis and, to a much lesser degree, SLE, mixed connective tissue disease, inflammatory myopathies, and Sjögren syndrome.
The pathogenesis of PAH in SLE is likely to be multifactorial. Several factors have been implicated, such as recurrent vasospasm, vasculitis, and thrombotic vascular occlusion. In addition, PH can be secondary to pulmonary fibrosis, chronic thromboembolic disease, and left ventricular dysfunction.
The symptoms of PAH in SLE are nonspecific and similar to those of patients with other forms of this condition. The most common complaints are dyspnea on exertion, chest pain, and chronic nonproductive cough.
PAH has been identified as a predictor of morbidity and mortality in SLE. Cardiac failure and sudden death, are the most common causes of death. The survival of patients with lupus and PAH has been considered poor. However, a British national registry of PH starting in 2001 has shown 1- and 3-year survival rates of 78% and 74%, respectively, for PAH secondary to SLE, significantly higher than those of systemic sclerosis–associated PAH. PMID: 18931333
These figures may reflect the availability of new, effective therapies for PAH, but also the differential, specific characteristics of SLE-associated PAH.