[The clinical characteristics of systemic sclerosis-related pulmonary arterial hypertension]

To study the clinical, cardiopulmonary functional and hemodynamic profiles of systemic sclerosis patients with pulmonary hypertension (SSc-PAH) compared with those of idiopathic pulmonary hypertension (IPAH).

Patients diagnosed with SSc-PAH or IPAH by right heart catheterization were consecutively enrolled into the study between 2011 and 2013 in Peking Union Medical College Hospital (PUMCH). Cases with pulmonary hypertension related to other diseases were excluded. Demographic data, laboratory parameters, 6 minutes walk distance (6MWD), pulmonary function and hemodynamic variables at the time of diagnosis were collected and compared between the two groups.

A total of 20 SSc-PAH patients including 19 females and one male with age of (43.1 ± 12.2) years, and 18 IPAH patients including 16 females and 2 males with age of (38.4 ± 12.4) years were enrolled in this study. Subjects in both groups had similar mean pulmonary arterial pressure, cardiac index and pulmonary vascular resistance (PVR) when recruited. Compared with IPAH patients, SSc-PAH patients showed significantly decreased all parameters including forced vital capacity (FVC)% [(77.1 ± 13.2)% vs (88.6 ± 14.9)%, P = 0.026], diffusing capacity of the lung for carbon monoxide (DLCO)% [(46.2 ± 13.1) % vs (66.6 ± 13.3)%, P < 0.001], DLCO/alveolar ventilation (VA) [(55.1 ± 14.3)% vs (75.1 ± 11.5)%, P < 0.001], and 6MWD [(365.6 ± 85.1) m vs (454.3 ± 136.8) m, P = 0.034]. In subgroup analysis of SSc-PAH patients, elevated PVR (OR 2.122, 95%CI 1.093-4.119, P = 0.026) and decreased DLCO% (OR 0.916, 95%CI 0.842-0.996, P = 0.040) were independently associated with reduced 6MWD.

Under the similar hemodynamic condition, SSc-PAH patients had more severe restrictive ventilation dysfunction and diffusion capacity dysfunction. Decreased 6MWD in SSc-PAH patients was probably related to the impairment of pulmonary function.